Telecom-wavelength single photons are essential components for long-distance quantum networks. However, bright and pure single photon sources at telecom wavelengths remain challenging to achieve. Here, we demonstrate a bright telecom-wavelength single photon source based on a tapered nanobeam containing InAs/InP quantum dots. The tapered nanobeam enables directional and Gaussian-like far-field emission of the quantum dots. As a result, using above-band excitation we obtain an end-to-end brightness of 4.1 +/- 0.1\% and first-lens brightness of 27.0 +/- 0.1\% at the -1300 nm wavelength. Furthermore, we adopt quasi-resonant excitation to reduce both multiphoton emission and decoherence from unwanted charge carriers. As a result, we achieve a coherence time of 523 +/- 16 ps and postselected Hong-Ou-Mandel visibility of 0 .91 +/- 0.09 along with a comparable first-lens brightness of 21.0 +/- 0.1\%. These results represent a major step toward a practical fiber-based single photon source at telecom wavelengths for long-distance quantum networks.

}, keywords = {Quantum Dots, single photon sources, telecom wavelength, two-photon interference}, issn = {1530-6984}, doi = {10.1021/acs.nanolett.0c03680}, author = {Lee, Chang-Min and Buyukkaya, Mustafa Atabey and Harper, Samuel and Aghaeimeibodi, Shahriar and Richardson, Christopher J. K. and Waks, Edo} } @article {sosnova_character_2021, title = {Character of motional modes for entanglement and sympathetic cooling of mixed-species trapped-ion chains}, journal = {Phys. Rev. A}, volume = {103}, number = {1}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, abstract = {Modular mixed-species ion-trap networks are a promising framework for scalable quantum information processing, where one species acts as a memory qubit and another as a communication qubit. This architecture requires high-fidelity mixed-species entangling gates to transfer information from communication to memory qubits through their collective motion. We investigate the character of the motional modes of mixed-species ion chains of various lengths and in various trap potentials for entangling operations and sympathetic cooling. We find that the laser power required for high-fidelity entangling gates based on transverse modes is at least an order of magnitude higher than that for gates based on axial modes for ion species with a large mass ratio. We also find that for even moderate mass differences, the transverse modes are much harder to cool than the axial modes regardless of the ion chain configuration. Therefore, transverse modes conventionally used for operations in single-species ion chains may not be well suited for mixed-species chains with widely different masses.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.103.012610}, author = {Sosnova, K. and Carter, A. and Monroe, C.} } @article {liang_coherence_2021, title = {Coherence and decoherence in the {Harper}-{Hofstadter} model}, journal = {Phys. Rev. Res.}, volume = {3}, number = {2}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {apr}, abstract = {We quantum simulated the 2D Harper-Hofstadter (HH) lattice model in a highly elongated tube geometry-three sites in circumference-using an atomic Bose-Einstein condensate. In addition to the usual transverse (out-of-plane) magnetic flux, piercing the surface of the tube, we threaded a longitudinal flux Phi(L) down the axis of the tube. This geometry evokes an Aharonov-Bohm interferometer, where noise in Phi(L) would readily decohere the interference present in trajectories encircling the tube. We observe this behavior only when transverse flux is a rational fraction of the flux quantum and remarkably find that for irrational fractions the decoherence is absent. Furthermore, at rational values of transverse flux, we show that the time evolution averaged over the noisy longitudinal flux matches the time evolution at nearby irrational fluxes. Thus, the appealing intuitive picture of an Aharonov-Bohm interferometer is insufficient. Instead, we quantitatively explain our observations by transforming the HH model into a collection of momentum-space Aubry-Andre models.}, doi = {10.1103/PhysRevResearch.3.023058}, author = {Liang, Q-Y and Trypogeorgos, D. and Valdes-Curiel, A. and Tao, J. and Zhao, M. and Spielman, I. B.} } @article {burenkov_coherent_2021, title = {Coherent optical processes with an all-optical atomic simulator}, journal = {Opt. Express}, volume = {29}, number = {1}, year = {2021}, note = {Place: 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA Publisher: OPTICAL SOC AMER Type: Article}, month = {jan}, pages = {330{\textendash}341}, abstract = {We show how novel photonic devices such as broadband quantum memory and efficient quantum frequency transduction can be implemented using three-wave mixing processes in a 1D array of nonlinear waveguides evanescently coupled to nearest neighbors. We do this using an analogy of an atom interacting with an external optical field using both classical and quantum models of the optical fields and adapting well-known coherent processes from atomic optics, such as electromagnetically induced transparency and stimulated Raman adiabatic passage to design. This approach allows the implementation of devices that are very difficult or impossible to implement by conventional techniques.}, issn = {1094-4087}, doi = {10.1364/OE.415480}, author = {Burenkov, Ivan A. and Novikova, Irina and Tikhonova, V, Olga and Polyakov, V, Sergey} } @article {curtis_critical_2021, title = {Critical theory for the breakdown of photon blockade}, journal = {Phys. Rev. Res.}, volume = {3}, number = {2}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, abstract = {Photon blockade is the result of the interplay between the quantized nature of light and strong optical nonlinearities, whereby strong photon-photon repulsion prevents a quantum optical system from absorbing multiple photons. We theoretically study a single atom coupled to the light field, described by the resonantly driven Jaynes-Cummings model, in which case the photon blockade breaks down in a second-order phase transition at a critical drive strength. We show that this transition is associated to the spontaneous breaking of an antiunitary PT symmetry. Within a semiclassical approximation, we calculate the expectation values of observables in the steady state. We then move beyond the semiclassical approximation and approach the critical point from the disordered (blockaded) phase by reducing the Lindblad quantum master equation to a classical rate equation that we solve. The width of the steady-state distribution in Fock space is found to diverge as we approach the critical point with a simple power law, allowing us to calculate the critical scaling of steady-state observables without invoking mean-field theory. We propose a simple physical toy model for biased diffusion in the space of occupation numbers, which captures the universal properties of the steady state. We list several experimental platforms where this phenomenon may be observed.}, doi = {10.1103/PhysRevResearch.3.023062}, author = {Curtis, Jonathan B. and Boettcher, Igor and Young, Jeremy T. and Maghrebi, Mohammad F. and Carmichael, Howard and Gorshkov, V, Alexey and Foss-Feig, Michael} } @article {manjunath_crystalline_2021, title = {Crystalline gauge fields and quantized discrete geometric response for {Abelian} topological phases with lattice symmetry}, journal = {Phys. Rev. Res.}, volume = {3}, number = {1}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jan}, abstract = {Clean isotropic quantum Hall fluids in the continuum possess a host of symmetry-protected quantized invariants, such as the Hall conductivity, shift, and Hall viscosity. Here we develop a theory of symmetry-protected quantized invariants for topological phases defined on a lattice, where quantized invariants with no continuum analog can arise. We develop topological field theories using discrete crystalline gauge fields to fully characterize quantized invariants of (2 + 1)D Abelian topological orders with symmetry group G = U(1) x G(space), where G(space) consists of orientation-preserving space group symmetries on the lattice. We show how discrete rotational and translational symmetry fractionalization can be characterized by a discrete spin vector, a discrete torsion vector which has no analog in the continuum or in the absence of lattice rotation symmetry, and an area vector, which also has no analog in the continuum. The discrete torsion vector implies a type of crystal momentum fractionalization that is only nontrivial for two, three, and fourfold rotation symmetry. The quantized topological response theory includes a discrete version of the shift, which binds fractional charge to disclinations and corners, a fractionally quantized angular momentum of disclinations, rotationally symmetric fractional charge polarization and its angular momentum counterpart, constraints on charge and angular momentum per unit cell, and quantized momentum bound to dislocations and units of area. The fractionally quantized charge polarization, which is nontrivial only on a lattice with two, three, and fourfold rotation symmetry, implies a fractional charge bound to lattice dislocations and a fractional charge per unit length along the boundary. An important role is played by a finite group grading on Burgers vectors, which depends on the point group symmetry of the lattice.}, doi = {10.1103/PhysRevResearch.3.013040}, author = {Manjunath, Naren and Barkeshli, Maissam} } @article {morong_disorder-controlled_2021, title = {Disorder-controlled relaxation in a three-dimensional {Hubbard} model quantum simulator}, journal = {Phys. Rev. Res.}, volume = {3}, number = {1}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jan}, abstract = {Understanding the collective behavior of strongly correlated electrons in materials remains a central problem in many-particle quantum physics. A minimal description of these systems is provided by the disordered Fermi-Hubbard model (DFHM), which incorporates the interplay of motion in a disordered lattice with local interparticle interactions. Despite its minimal elements, many dynamical properties of the DFHM are not well understood, owing to the complexity of systems combining out-of-equilibrium behavior, interactions, and disorder in higher spatial dimensions. Here, we study the relaxation dynamics of doubly occupied lattice sites in the three-dimensional DFHM using interaction-quench measurements on a quantum simulator composed of fermionic atoms confined in an optical lattice. In addition to observing the widely studied effect of disorder inhibiting relaxation, we find that the cooperation between strong interactions and disorder also leads to the emergence of a dynamical regime characterized by disorder-enhanced relaxation. To support these results, we develop an approximate numerical method and a phenomenological model that each capture the essential physics of the decay dynamics. Our results provide a theoretical framework for a previously inaccessible regime of the DFHM and demonstrate the ability of quantum simulators to enable understanding of complex many-body systems through minimal models.}, doi = {10.1103/PhysRevResearch.3.L012009}, author = {Morong, W. and Muleady, S. R. and Kimchi, I and Xu, W. and Nandkishore, R. M. and Rey, A. M. and DeMarco, B.} } @article {baldwin_distinct_2021, title = {Distinct critical behaviors from the same state in quantum spin and population dynamics perspectives}, journal = {Phys. Rev. E}, volume = {103}, number = {1}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jan}, abstract = {There is a deep connection between the ground states of transverse-field spin systems and the late-time distributions of evolving viral populations-within simple models, both are obtained from the principal eigen-vector of the same matrix. However, that vector is the wave-function amplitude in the quantum spin model, whereas it is the probability itself in the population model. We show that this seemingly minor difference has significant consequences: Phase transitions that are discontinuous in the spin system become continuous when viewed through the population perspective, and transitions that are continuous become governed by new critical exponents. We introduce a more general class of models that encompasses both cases and that can be solved exactly in a mean-field limit. Numerical results are also presented for a number of one-dimensional chains with power-law interactions. We see that well-worn spin models of quantum statistical mechanics can contain unexpected new physics and insights when treated as population-dynamical models and beyond, motivating further studies.}, issn = {2470-0045}, doi = {10.1103/PhysRevE.103.012106}, author = {Baldwin, C. L. and Shivam, S. and Sondhi, S. L. and Kardar, M.} } @article {21096, title = {Domain-wall confinement and dynamics in a quantum simulator}, journal = {Nat. Phys.}, year = {2021}, abstract = {Particles subject to confinement experience an attractive potential that increases without bound as they separate. A prominent example is colour confinement in particle physics, in which baryons and mesons are produced by quark confinement. Confinement can also occur in low-energy quantum many-body systems when elementary excitations are confined into bound quasiparticles. Here we report the observation of magnetic domain-wall confinement in interacting spin chains with a trapped-ion quantum simulator. By measuring how correlations spread, we show that confinement can suppress information propagation and thermalization in such many-body systems. We quantitatively determine the excitation energy of domain-wall bound states from the non-equilibrium quench dynamics. We also study the number of domain-wall excitations created for different quench parameters, in a regime that is difficult to model with classical computers. This work demonstrates the capability of quantum simulators for investigating high-energy physics phenomena, such as quark collision and string breaking. Long-range Ising interactions present in one-dimensional spin chains can induce a confining potential between pairs of domain walls, slowing down the thermalization of the system. This has now been observed in a trapped-ion quantum simulator.

}, issn = {1745-2473}, doi = {10.1038/s41567-021-01194-3}, author = {Tan, W. L. and Becker, P. and Liu, F. and Pagano, G. and Collins, K. S. and De, A. and Feng, L. and Kaplan, H. B. and Kyprianidis, A. and Lundgren, R. and Morong, W. and Whitsitt, S. and Gorshkov, A. V. and Monroe, C.} } @article {lu_efficient_2021, title = {Efficient photoinduced second-harmonic generation in silicon nitride photonics}, journal = {Nat. Photonics}, volume = {15}, number = {2}, year = {2021}, note = {Place: HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY Publisher: NATURE RESEARCH Type: Article}, month = {feb}, pages = {131+}, abstract = {Silicon photonics lacks a second-order nonlinear optical (chi((2))) response in general, because the typical constituent materials are centrosymmetric and lack inversion symmetry, which prohibits chi((2)) nonlinear processes such as second-harmonic generation (SHG). Here, we realize high SHG efficiency in silicon photonics by combining a photoinduced effective chi((2)) nonlinearity with resonant enhancement and perfect phase matching. We show a conversion efficiency of (2,500 +/- 100)\% W-1 that is two to four orders of magnitude larger than previous field-induced SHG works. In particular, our devices realize milliwatt-level SHG output powers with up to (22 +/- 1)\% power conversion efficiency. This demonstration is a breakthrough in realizing efficient chi((2)) processes in silicon photonics, and paves the way for further integration of self-referenced frequency combs and optical frequency references.}, issn = {1749-4885}, doi = {10.1038/s41566-020-00708-4}, author = {Lu, Xiyuan and Moille, Gregory and Rao, Ashutosh and Westly, Daron A. and Srinivasan, Kartik} } @article {van_regemortel_entanglement_2021, title = {Entanglement {Entropy} {Scaling} {Transition} under {Competing} {Monitoring} {Protocols}}, journal = {Phys. Rev. Lett.}, volume = {126}, number = {12}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {mar}, abstract = {Dissipation generally leads to the decoherence of a quantum state. In contrast, numerous recent proposals have illustrated that dissipation can also be tailored to stabilize many-body entangled quantum states. While the focus of these works has been primarily on engineering the nonequilibrium steady state, we investigate the buildup of entanglement in the quantum trajectories. Specifically, we analyze the competition between two different dissipation channels arising from two incompatible continuous monitoring protocols. The first protocol locks the phase of neighboring sites upon registering a quantum jump, thereby generating a long-range entanglement through the system, while the second destroys the coherence via a dephasing mechanism. By studying the unraveling of stochastic quantum trajectories associated with the continuous monitoring protocols, we present a transition for the scaling of the averaged trajectory entanglement entropies, from critical scaling to area-law behavior. Our work provides an alternative perspective on the measurement-induced phase transition: the measurement can be viewed as monitoring and registering quantum jumps, offering an intriguing extension of these phase transitions through the long-established realm of quantum optics.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.126.123604}, author = {Van Regemortel, Mathias and Cian, Ze-Pei and Seif, Alireza and Dehghani, Hossein and Hafezi, Mohammad} } @article {zeuner_experimental_2021, title = {Experimental quantum homomorphic encryption}, journal = {npj Quantum Inform.}, volume = {7}, number = {1}, year = {2021}, note = {Place: HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY Publisher: NATURE RESEARCH Type: Article}, month = {feb}, abstract = {Quantum computers promise not only to outperform classical machines for certain important tasks, but also to preserve privacy of computation. For example, the blind quantum computing protocol enables secure delegated quantum computation, where a client can protect the privacy of their data and algorithms from a quantum server assigned to run the computation. However, this security comes with the practical limitation that the client and server must communicate after each step of computation. A practical alternative is homomorphic encryption, which does not require any interactions, while providing quantum-enhanced data security for a variety of computations. In this scenario, the server specifies the computation to be performed, and the client provides only the input data, thus enabling secure noninteractive computation. Here, we demonstrate homomorphic-encrypted quantum computing with unitary transformations of individual qubits, as well as multi-qubit quantum walk computations using single-photon states and non-birefringent integrated optics. The client encrypts their input in the photons{\textquoteright} polarization state, while the server performs the computation using the path degree of freedom. Our demonstration using integrated quantum photonics underlines the applicability of homomorphic-encrypted quantum computations, and shows the potential for delegated quantum computing using photons.}, doi = {10.1038/s41534-020-00340-8}, author = {Zeuner, Jonas and Pitsios, Ioannis and Tan, Si-Hui and Sharma, Aditya N. and Fitzsimons, Joseph F. and Osellame, Roberto and Walther, Philip} } @article {dehghani_extraction_2021, title = {Extraction of the many-body {Chern} number from a single wave function}, journal = {Phys. Rev. B}, volume = {103}, number = {7}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {feb}, abstract = {The quantized Hall conductivity of integer and fractional quantum Hall (IQH and FQH) states is directly related to a topological invariant, the many-body Chern number. The conventional calculation of this invariant in interacting systems requires a family of many-body wave functions parameterized by twist angles to calculate the Berry curvature. In this paper, we demonstrate how to extract the Chern number given a single many-body wave function, without knowledge of the Hamiltonian. For FQH states, our method requires one additional integer invariant as input: the number of 2 pi flux quanta, s, that must be inserted to obtain a topologically trivial excitation. As we discuss, s can be obtained in principle from the degenerate set of ground state wave functions on the torus, without knowledge of the Hamiltonian. We perform extensive numerical simulations involving IQH and FQH states to validate these methods.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.103.075102}, author = {Dehghani, Hossein and Cian, Ze-Pei and Hafezi, Mohammad and Barkeshli, Maissam} } @article {huang_faithful_2021, title = {Faithful derivation of symmetry indicators: {A} case study for topological superconductors with time-reversal and inversion symmetries}, journal = {Phys. Rev. Res.}, volume = {3}, number = {1}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {mar}, abstract = {Topological crystalline superconductors have attracted rapidly rising attention due to the possibility of higher-order phases, which support Majorana modes on boundaries in d - 2 or lower dimensions. However, although the classification and bulk topological invariants in such systems have been well studied, it is generally difficult to faithfully predict the boundary Majoranas from the band-structure information due to the lack of well-established bulk-boundary correspondence. Here we propose a protocol for deriving symmetry indicators that depend on a minimal set of necessary symmetry data of the bulk bands and can diagnose boundary features. Specifically, to obtain indicators manifesting clear bulk-boundary correspondence, we combine the topological crystal classification scheme in real space and a twisted equivariant K-group analysis in momentum space. The key step is to disentangle the generally mixed strong and weak indicators through a systematic basis-matching procedure between our real-space and momentum-space approaches. We demonstrate our protocol using an example of two-dimensional time-reversal odd-parity superconductors, where the inversion symmetry is known to protect a higher-order phase with corner Majoranas. Symmetry indicators derived from our protocol can be readily applied to an ab initio database and could fuel material predictions for strong and weak topological crystalline superconductors with various boundary features.}, doi = {10.1103/PhysRevResearch.3.013243}, author = {Huang, Sheng-Jie and Hsu, Yi-Ting} } @article {mueller_single-particle-like_2021, title = {From single-particle-like to interaction-mediated plasmonic resonances in graphene nanoantennas}, journal = {J. Appl. Phys.}, volume = {129}, number = {9}, year = {2021}, note = {Place: 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA Publisher: AMER INST PHYSICS Type: Article}, month = {mar}, abstract = {Plasmonic nanostructures attract tremendous attention as they confine electromagnetic fields well below the diffraction limit while simultaneously sustaining extreme local field enhancements. To fully exploit these properties, the identification and classification of resonances in such nanostructures is crucial. Recently, a novel figure of merit for resonance classification has been proposed [Muller et al., J. Phys. Chem. C 124, 24331-24343 (2020)] and its applicability was demonstrated mostly to toy model systems. This novel measure, the energy-based plasmonicity index (EPI), characterizes the nature of resonances in molecular nanostructures. The EPI distinguishes between either a single-particle-like or a plasmonic nature of resonances based on the energy space coherence dynamics of the excitation. To advance the further development of this newly established measure, we present here its exemplary application to characterize the resonances of graphene nanoantennas. In particular, we focus on resonances in a doped nanoantenna. The structure is of interest, as a consideration of the electron dynamics in real space might suggest a plasmonic nature of selected resonances in the low doping limit but our analysis reveals the opposite. We find that in the undoped and moderately doped nanoantenna, the EPI classifies all emerging resonances as predominantly single-particle-like, and only after doping the structure heavily, the EPI observes plasmonic response.}, issn = {0021-8979}, doi = {10.1063/5.0038883}, author = {Mueller, Marvin M. and Kosik, Miriam and Pelc, Marta and Bryant, Garnett W. and Ayuela, Andres and Rockstuhl, Carsten and Slowik, Karolina} } @article {green_how_2021, title = {How to profit from quantum technology without building quantum computers}, journal = {Nat. Rev. Phys.}, volume = {3}, number = {3}, year = {2021}, note = {Place: CAMPUS, 4 CRINAN ST, LONDON, N1 9XW, ENGLAND Publisher: SPRINGERNATURE Type: Editorial Material}, month = {mar}, pages = {150{\textendash}152}, abstract = {There are a number of lower risk opportunities to invest in quantum technologies, other than quantum computers, but to make the most of them both specialist knowledge and market awareness are required.}, doi = {10.1038/s42254-021-00290-w}, author = {Green, Dmitry and Soller, Henning and Oreg, Yuval and Galitski, Victor} } @article {briles_hybrid_2021, title = {Hybrid {InP} and {SiN} integration of an octave-spanning frequency comb}, journal = {APL Phontonics}, volume = {6}, number = {2}, year = {2021}, note = {Place: 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA Publisher: AMER INST PHYSICS Type: Article}, month = {feb}, abstract = {Implementing optical-frequency combs with integrated photonics will enable wider use of precision timing signals. Here, we explore the generation of an octave-span, Kerr-microresonator frequency comb using hybrid integration of an InP distributed-feedback laser and a SiN photonic-integrated circuit. We demonstrate electrically pumped and fiber-packaged prototype systems, enabled by self-injection locking. This direct integration of a laser and a microresonator circuit without previously used intervening elements, such as optical modulators and isolators, necessitates understanding self-injection-locking dynamics with octave-span Kerr solitons. In particular, system architectures must adjust to the strong coupling of microresonator backscattering and laser-microresonator frequency detuning that we uncover here. Our work illustrates critical considerations toward realizing a self-referenced frequency comb with integrated photonics.}, issn = {2378-0967}, doi = {10.1063/5.0035452}, author = {Briles, Travis C. and Yu, Su-Peng and Chang, Lin and Xiang, Chao and Guo, Joel and Kinghorn, David and Moille, Gregory and Srinivasan, Kartik and Bowers, John E. and Papp, Scott B.} } @article {han_lattice_2021, title = {Lattice vibration as a knob on exotic quantum criticality}, journal = {Phys. Rev. B}, volume = {103}, number = {1}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jan}, abstract = {Control of quantum coherence in a many-body system is one of the key issues in modern condensed matter, and conventional wisdom is that lattice vibration is an innate source of decoherence. Much research has been conducted to eliminate lattice effects. Challenging this wisdom, we show that lattice vibration may not be a decoherence source but an impetus of a novel coherent quantum many-body state. We demonstrate the possibility by studying the transverse-field Ising model on a chain with renormalization group and density-matrix renormalization group methods and theoretically discover a stable N = 1 supersymmetric quantum criticality with central charge c = 3/2. Thus, we propose an Ising spin chain with strong spin-lattice coupling as a candidate to observe supersymmetry. Generic precursor conditions of novel quantum criticality are obtained by generalizing the Larkin-Pikin criterion of thermal transitions. Our work provides the perspective that lattice vibration may be a knob for exotic quantum many-body states.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.103.014435}, author = {Han, SangEun and Lee, Junhyun and Moon, Eun-Gook} } @article {de_bernardis_light-matter_2021, title = {Light-{Matter} {Interactions} in {Synthetic} {Magnetic} {Fields}: {Landau}-{Photon} {Polaritons}}, journal = {Phys. Rev. Lett.}, volume = {126}, number = {10}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {mar}, abstract = {We study light-matter interactions in two-dimensional photonic systems in the presence of a spatially homogeneous synthetic magnetic field for light. Specifically, we consider one or more two-level emitters located in the bulk region of the lattice, where for increasing magnetic field the photonic modes change from extended plane waves to circulating Landau levels. This change has a drastic effect on the resulting emitter-field dynamics, which becomes intrinsically non-Markovian and chiral, leading to the formation of strongly coupled Landau-photon polaritons. The peculiar dynamical and spectral properties of these quasiparticles can be probed with state-of-the-art photonic lattices in the optical and the microwave domain and may find various applications for the quantum simulation of strongly interacting topological models.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.126.103603}, author = {De Bernardis, Daniele and Cian, Ze-Pei and Carusotto, Iacopo and Hafezi, Mohammad and Rabl, Peter} } @article {dehghani_light-induced_2021, title = {Light-induced topological superconductivity via {Floquet} interaction engineering}, journal = {Phys. Rev. Res.}, volume = {3}, number = {2}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {apr}, abstract = {We propose a mechanism for light-induced unconventional superconductivity in a two-valley semiconductor with a massive Dirac-type band structure. The superconducting phase results from the out-of-equilibrium excitation of carriers in the presence of Coulomb repulsion and is stabilized by coupling the driven semiconductor to a bosonic or fermionic thermal bath. We consider a circularly polarized light pump and show that by controlling the detuning of the pump frequency relative to the band gap, different types of chiral superconductivity would be induced. The emergence of novel superconducting states, such as the chiral p-wave pairing, results from the Floquet engineering of the interaction. This is realized by modifying the form of the Coulomb interaction by projecting it into the states that are resonant with the pump frequency. We show that the resulting unconventional pairing in our system can host topologically protected chiral bound states. We discuss a promising experimental platform to realize our proposal and detect the signatures of the emergent superconducting state.}, doi = {10.1103/PhysRevResearch.3.023039}, author = {Dehghani, Hossein and Hafezi, Mohammad and Ghaemi, Pouyan} } @article {wayne_low-noise_2021, title = {Low-noise photon counting above 100 x 10(6) counts per second with a high-efficiency reach-through single-photon avalanche diode system}, journal = {Appl. Phys. Lett.}, volume = {118}, number = {13}, year = {2021}, note = {Place: 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA Publisher: AMER INST PHYSICS Type: Article}, abstract = {We demonstrate a method that allows a high-efficiency single-photon-avalanche diode (SPAD) with a thick absorption region ({\textgreater}10 mu m) to count single photons at rates significantly higher than previously demonstrated. We apply large ({\textgreater}30V) AC bias gates to the SPAD at 1GHz and detect minute avalanches with a discrimination threshold of 5(1) mV by means of radio frequency interferometry. We measure a reduction by a factor of approximate to 500 in the average charge per avalanche when compared to operation in its traditional active-quenching module and a relative increase in {\textgreater}19\% in detection efficiency at 850nm. The reduction in charge strongly suppresses self-heating effects in the diode that can degrade performance at high avalanche rates. We show that the single-photon detection system maintains high efficiency at count rates exceeding 10(8) s(-1).}, issn = {0003-6951}, doi = {10.1063/5.0041984}, author = {Wayne, Michael A. and Bienfang, Joshua C. and Migdall, Alan L.} } @article {seif_machine_2021, title = {Machine learning the thermodynamic arrow of time}, journal = {Nat. Phys.}, volume = {17}, number = {1}, year = {2021}, note = {Place: HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY Publisher: NATURE RESEARCH Type: Article}, month = {jan}, abstract = {The asymmetry in the flow of events that is expressed by the phrase {\textquoteleft}time{\textquoteright}s arrow{\textquoteright} traces back to the second law of thermodynamics. In the microscopic regime, fluctuations prevent us from discerning the direction of time{\textquoteright}s arrow with certainty. Here, we find that a machine learning algorithm that is trained to infer the direction of time{\textquoteright}s arrow identifies entropy production as the relevant physical quantity in its decision-making process. Effectively, the algorithm rediscovers the fluctuation theorem as the underlying thermodynamic principle. Our results indicate that machine learning techniques can be used to study systems that are out of equilibrium, and ultimately to answer open questions and uncover physical principles in thermodynamics. The phrase {\textquoteleft}arrow of time{\textquoteright} refers to the asymmetry in the flow of events. A machine learning algorithm trained to infer its direction identifies entropy production as the relevant underlying physical principle in the decision-making process.}, issn = {1745-2473}, doi = {10.1038/s41567-020-1018-2}, author = {Seif, Alireza and Hafezi, Mohammad and Jarzynski, Christopher} } @article {mcgehee_magneto-optical_2021, title = {Magneto-optical trapping using planar optics}, journal = {New J. Phys.}, volume = {23}, number = {1}, year = {2021}, note = {Place: TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND Publisher: IOP PUBLISHING LTD Type: Article}, month = {jan}, abstract = {Laser-cooled atoms are a key technology for many calibration-free measurement platforms-including clocks, gyroscopes, and gravimeters-and are a promising system for quantum networking and quantum computing. The optics and vacuum hardware required to prepare these gases are often bulky and not amenable to large-volume manufacturing, limiting the practical realization of devices benefiting from the properties of cold atoms. Planar, lithographically produced optics including photonic integrated circuits, optical metasurfaces (MSs), and gratings offer a pathway to develop chip-scale, manufacturable devices utilizing cold atoms. As a demonstration of this technology, we have realized laser cooling of atomic Rb in a grating-type magneto-optical trap (MOT) using planar optics for beam launching, beam shaping, and polarization control. Efficient use of available light is accomplished using MS-enabled beam shaping, and the performance of the planar optics MOT is competitive with Gaussian-beam illuminated grating MOTs.}, keywords = {laser cooling, metasurfaces, photonic integrated circuits}, issn = {1367-2630}, doi = {10.1088/1367-2630/abdce3}, author = {McGehee, William R. and Zhu, Wenqi and Barker, Daniel S. and Westly, Daron and Yulaev, Alexander and Klimov, Nikolai and Agrawal, Amit and Eckel, Stephen and Aksyuk, Vladimir and McClelland, Jabez J.} } @article {wang_magnetotransport_2021, title = {Magnetotransport in hybrid {InSe}/monolayer graphene on {SiC}}, journal = {Nanotechnology}, volume = {32}, number = {15}, year = {2021}, note = {Place: TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND Publisher: IOP PUBLISHING LTD Type: Article}, month = {apr}, abstract = {The magnetotransport properties of a hybrid InSe/monolayer graphene in a SiC system are systematically studied. Compared to those of its bare graphene counterpart, in InSe/graphene, we can effectively modify the carrier density, mobility, effective mass, and electron-electron (e-e) interactions enhanced by weak disorder. We show that in bare graphene and hybrid InSe/graphene systems, the logarithmic temperature (lnT) dependence of the Hall slope R-H = delta R-xy/delta B = delta rho(xy)/delta B can be used to probe e-e interaction effects at various temperatures even when the measured resistivity does not show a lnT dependence due to strong electron-phonon scattering. Nevertheless, one needs to be certain that the change of R-H is not caused by an increase of the carrier density by checking the magnetic field position of the longitudinal resistivity minimum at different temperatures. Given the current challenges in gating graphene on SiC with a suitable dielectric layer, our results suggest that capping a van der Waals material on graphene is an effective way to modify the electronic properties of monolayer graphene on SiC.

}, keywords = {graphene, Hall effect, InSe, interactions}, issn = {0957-4484}, doi = {10.1088/1361-6528/abd726}, author = {Wang, Chih-Yuan and Lin, Yun-Wu and Chuang, Chiashain and Yang, Cheng-Hsueh and Patel, Dinesh K. and Chen, Sheng-Zong and Yeh, Ching-Chen and Chen, Wei-Chen and Lin, Chia-Chun and Chen, Yi-Hsun and Wang, Wei-Hua and Sankar, Raman and Chou, Fang-Cheng and Kruskopf, Mattias and Elmquist, Randolph E. and Liang, Chi-Te} } @article {cian_many-body_2021, title = {Many-{Body} {Chern} {Number} from {Statistical} {Correlations} of {Randomized} {Measurements}}, journal = {Phys. Rev. Lett.}, volume = {126}, number = {5}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {feb}, abstract = {One of the main topological invariants that characterizes several topologically ordered phases is the many-body Chern number (MBCN). Paradigmatic examples include several fractional quantum Hall phases, which are expected to be realized in different atomic and photonic quantum platforms in the near future. Experimental measurement and numerical computation of this invariant are conventionally based on the linear-response techniques that require having access to a family of states, as a function of an external parameter, which is not suitable for many quantum simulators. Here, we propose an ancilla-free experimental scheme for the measurement of this invariant, without requiring any knowledge of the Hamiltonian. Specifically, we use the statistical correlations of randomized measurements to infer the MBCN of a wave function. Remarkably, our results apply to disklike geometries that are more amenable to current quantum simulator architectures.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.126.050501}, author = {Cian, Ze-Pei and Dehghani, Hossein and Elben, Andreas and Vermersch, Benoit and Zhu, Guanyu and Barkeshli, Maissam and Zoller, Peter and Hafezi, Mohammad} } @article {chou_marginally_2021, title = {Marginally localized edges of time-reversal symmetric topological superconductors}, journal = {Phys. Rev. B}, volume = {103}, number = {7}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {feb}, abstract = {We demonstrate that the one-dimensional helical Majorana edges of two-dimensional time-reversal symmetric topological superconductors (class DIII) can become gapless and insulating by a combination of random edge velocity and interaction. Such a gapless insulating edge breaks time-reversal symmetry inhomogeneously, and the local symmetry broken regions can be regarded as static mass potentials or dynamical Ising spins. In both limits, we find that such gapless insulating Majorana edges are generically exponentially localized and trap Majorana zero modes. Interestingly, for a statistically time-reversal symmetric edge (symmetry is broken locally, but the symmetry breaking order parameter is zero on average), the low-energy theory can be mapped to a Dyson model at zero energy, manifesting a diverging density of states and exhibiting marginal localization (i.e., a diverging localization length). Although the ballistic edge state transport is absent, the localized Majorana zero modes reflect the nontrivial topology in the bulk. Experimental signatures are also discussed.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.103.075120}, author = {Chou, Yang-Zhi and Nandkishore, Rahul M.} } @article {lavasani_measurement-induced_2021, title = {Measurement-induced topological entanglement transitions in symmetric random quantum circuits}, journal = {Nat. Phys.}, volume = {17}, number = {3}, year = {2021}, note = {Place: HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY Publisher: NATURE RESEARCH Type: Article}, month = {mar}, pages = {342+}, abstract = {Random quantum circuits, in which an array of qubits is subjected to a series of randomly chosen unitary operations, have provided key insights into the dynamics of many-body quantum entanglement. Recent work has shown that interleaving the unitary operations with single-qubit measurements can drive a transition between high- and low-entanglement phases. Here we study a class of symmetric random quantum circuits with two competing types of measurement in addition to unitary dynamics. We find a rich phase diagram involving robust symmetry-protected topological, trivial and volume law entangled phases, where the transitions are hidden to expectation values of any operator and are only apparent by averaging the entanglement entropy over quantum trajectories. In the absence of unitary dynamics, we find a purely measurement-induced critical point, which maps exactly to two copies of a classical two-dimensional percolation problem. Numerical simulations indicate that this transition is a tricritical point that splits into two critical lines in the presence of arbitrarily sparse unitary dynamics with an intervening volume law entangled phase. Our results show that measurements alone are sufficient to induce criticality and logarithmic entanglement scaling, and arbitrarily sparse unitary dynamics can be sufficient to stabilize volume law entangled phases in the presence of rapid, yet competing, measurements.}, issn = {1745-2473}, doi = {10.1038/s41567-020-01112-z}, author = {Lavasani, Ali and Alavirad, Yahya and Barkeshli, Maissam} } @article {carney_mechanical_2021, title = {Mechanical quantum sensing in the search for dark matter}, journal = {Quantum Sci. Technol.}, volume = {6}, number = {2}, year = {2021}, note = {Place: TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND Publisher: IOP PUBLISHING LTD Type: Article}, month = {apr}, abstract = {Numerous astrophysical and cosmological observations are best explained by the existence of dark matter, a mass density which interacts only very weakly with visible, baryonic matter. Searching for the extremely weak signals produced by this dark matter strongly motivate the development of new, ultra-sensitive detector technologies. Paradigmatic advances in the control and readout of massive mechanical systems, in both the classical and quantum regimes, have enabled unprecedented levels of sensitivity. In this white paper, we outline recent ideas in the potential use of a range of solid-state mechanical sensing technologies to aid in the search for dark matter in a number of energy scales and with a variety of coupling mechanisms.}, keywords = {dark matter, Optomechanics, quantum sensing, standard quantum limits}, issn = {2058-9565}, doi = {10.1088/2058-9565/abcfcd}, author = {Carney, D. and Krnjaic, G. and Moore, D. C. and Regal, C. A. and Afek, G. and Bhave, S. and Brubaker, B. and Corbitt, T. and Cripe, J. and Crisosto, N. and Geraci, A. and Ghosh, S. and Harris, J. G. E. and Hook, A. and Kolb, E. W. and Kunjummen, J. and Lang, R. F. and Li, T. and Lin, T. and Liu, Z. and Lykken, J. and Magrini, L. and Manley, J. and Matsumoto, N. and Monte, A. and Monteiro, F. and Purdy, T. and Riedel, C. J. and Singh, R. and Singh, S. and Sinha, K. and Taylor, J. M. and Qin, J. and Wilson, D. J. and Zhao, Y.} } @article {ahn_microscopic_2021, title = {Microscopic bath effects on noise spectra in semiconductor quantum dot qubits}, journal = {Phys. Rev. B}, volume = {103}, number = {4}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jan}, abstract = {When a system is thermally coupled to only a small part of a larger bath, statistical fluctuations of the temperature (more precisely, the internal energy) of this {\textquotedblleft}sub-bath{\textquotedblright} around the mean temperature defined by the larger bath can become significant. We show that these temperature fluctuations generally give rise to 1/f-like noise power spectral density from even a single two-level system. We extend these results to a distribution of fluctuators, finding the corresponding modification to the Dutta-Horn relation. Then we consider the specific situation of charge noise in silicon quantum dot qubits and show that recent experimental data [E. J. Connors et al., Phys. Rev. B 100, 165305 (2019)] can be modeled as arising from as few as two two-level fluctuators, and accounting for sub-bath size improves the quality of the fit.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.103.L041304}, author = {Ahn, Seongjin and Das Sarma, S. and Kestner, J. P.} } @article {vu_moire_2021, title = {Moire versus {Mott}: {Incommensuration} and {Interaction} in {One}-{Dimensional} {Bichromatic} {Lattices}}, journal = {Phys. Rev. Lett.}, volume = {126}, number = {3}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jan}, abstract = {Inspired by the rich physics of twisted 2D bilayer moire systems, we study Coulomb interacting systems subjected to two overlapping finite ID lattice potentials of unequal periods through exact numerical diagonalization. Unmatching underlying lattice periods lead to a 1D bichromatic {\textquotedblleft}moire{\textquotedblright} superlattice with a large unit cell and consequently a strongly flattened band, exponentially enhancing the effective dimensionless electron-electron interaction strength and manifesting clear signatures of enhanced Mott gaps at discrete fillings. An important nonperturbative finding is a remarkable fine-tuning effect of the precise lattice commensuration, where slight variations in the relative lattice periods may lead to a suppression of the correlated insulating phase, in qualitative agreement with the observed fragility of the correlated insulating phase in twisted bilayer graphene. Our predictions, which should be directly verifiable in bichromatic optical lattices, establish that the competition between interaction and incommensuration is a key element of the physics of moire superlattices.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.126.036803}, author = {Vu, DinhDuy and Sankar Das Sarma} } @article {yang_momentum_2021, title = {Momentum space toroidal moment in a photonic metamaterial}, journal = {Nat. Commun.}, volume = {12}, number = {1}, year = {2021}, note = {Place: HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY Publisher: NATURE RESEARCH Type: Article}, month = {mar}, abstract = {Berry curvature, the counterpart of the magnetic field in the momentum space, plays a vital role in the transport of electrons in condensed matter physics. It also lays the foundation for the emerging field of topological physics. In the three-dimensional systems, much attention has been paid to Weyl points, which serve as sources and drains of Berry curvature. Here, we demonstrate a toroidal moment of Berry curvature with flux approaching to in judiciously engineered metamaterials. The Berry curvature exhibits a vortex-like configuration without any source and drain in the momentum space. Experimentally, the presence of Berry curvature toroid is confirmed by the observation of conical-frustum shaped domain-wall states at the interfaces formed by two metamaterials with opposite toroidal moments. The appearance of toroidal multipolar moments in electrodynamics interrogates the question for their existence in Berry curvature, which can be seen as the {\textquotedblleft}magnetic field{\textquotedblright} in the momentum space. Here, the authors observe 3D vortex distributions in the Berry curvature within a photonic metamaterial.}, issn = {2041-1723}, doi = {10.1038/s41467-021-22063-w}, author = {Yang, Biao and Bi, Yangang and Zhang, Rui-Xing and Zhang, Ruo-Yang and You, Oubo and Zhu, Zhihong and Feng, Jing and Sun, Hongbo and Chan, C. T. and Liu, Chao-Xing and Zhang, Shuang} } @article {orek_no_2021, title = {{NO}+ + {H}-2: {Potential} energy surface and bound state calculations}, journal = {Chem. Phys. Lett.}, volume = {771}, year = {2021}, note = {Place: RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS Publisher: ELSEVIER Type: Article}, abstract = {The first four-dimensional (4D) adiabatic potential energy surface (PES) for the interaction of NO+ cation with the H-2 molecule has been accurately determined using the CCSD(T)-F12a method with cc-pVTZ-F12 basis set augmented with mid-bond functions. A detailed characterization of the PES and lowest bound states of the H-2-NO+ complex have been provided. The H-2-NO+ PES exhibits a single global minimum with a well depth of 824.63 cm(-1) corresponding to off-planar structure with the H-2 molecule in a perpendicular orientation to the NO+ cation. The solution of the nuclear Schrodinger equation for the bound states gives a zero-point energy corrected dissociation energy of D-0 = 498.15 cm(-1) for para-H-2-NO+ complex, and of 541.35 cm(-1) for ortho-H-2-NO+.

}, keywords = {Bound states calculations, Potential energy surface}, issn = {0009-2614}, doi = {10.1016/j.cplett.2021.138511}, author = {Orek, Cahit and Uminski, Marcin and Klos, Jacek and Lique, Francois and Zuchowski, Piotr S. and Bulut, Niyazi} } @article {hsiang_nonequilibrium_2021, title = {Nonequilibrium quantum free energy and effective temperature, generating functional, and influence action}, journal = {Phys. Rev. D}, volume = {103}, number = {6}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {mar}, abstract = {A definition of nonequilibrium free energy F-s is proposed for dynamical Gaussian quantum open systems strongly coupled to a heat bath and the formal relation with the generating functional, the coarse-grained effective action and the influence action is indicated. For Gaussian open quantum systems exemplified by the quantum Brownian motion model studied here, a time-varying effective temperature can be introduced in a natural way, and, with it, the nonequilibrium free energy F-s, von Neumann entropy S-vN and internal energy U-s of the reduced system (S) can be defined accordingly. In contrast to the nonequilibrium free energy found in the literature which references the bath temperature, the nonequilibrium thermodynamic functions we find here obey the familiar relation F-s(t) = U-s(t)-T-EFF(t)S-vN(t) at any and all moments of time in the system{\textquoteright}s fully nonequilibrium evolution history. After the system equilibrates they coincide, in the weak coupling limit, with their counterparts in conventional equilibrium thermodynamics. Since the effective temperature captures both the state of the system and its interaction with the bath, upon the system{\textquoteright}s equilibration, it approaches a value slightly higher than the initial bath temperature. Notably, it remains nonzero for a zero-temperature bath, signaling the existence of system-bath entanglement. Reasonably, at high bath temperatures and under ultraweak couplings, it becomes indistinguishable from the bath temperature. The nonequilibrium thermodynamic functions and relations discovered here for dynamical Gaussian quantum systems should open up useful pathways toward establishing meaningful theories of nonequilibrium quantum thermodynamics.}, issn = {2470-0010}, doi = {10.1103/PhysRevD.103.065001}, author = {Hsiang, Jen-Tsung and Hu, Bei-Lok} } @article {jian_note_2021, title = {Note on entropy dynamics in the {Brownian} {SYK} model}, journal = {J. High Energy Phys.}, number = {3}, year = {2021}, note = {Place: ONE NEW YORK PLAZA, SUITE 4600, NEW YORK, NY, UNITED STATES Publisher: SPRINGER Type: Article}, month = {mar}, abstract = {We study the time evolution of Renyi entropy in a system of two coupled Brownian SYK clusters evolving from an initial product state. The Renyi entropy of one cluster grows linearly and then saturates to the coarse grained entropy. This Page curve is obtained by two different methods, a path integral saddle point analysis and an operator dynamics analysis. Using the Brownian character of the dynamics, we derive a master equation which controls the operator dynamics and gives the Page curve for purity. Insight into the physics of this complicated master equation is provided by a complementary path integral method: replica diagonal and non-diagonal saddles are responsible for the linear growth and saturation of Renyi entropy, respectively.}, keywords = {AdS-CFT Correspondence, Black Holes, Nonperturbative Effects, Random Systems}, issn = {1029-8479}, doi = {10.1007/JHEP03(2021)042}, author = {Jian, Shao-Kai and Swingle, Brian} } @article {walter_observation_2021, title = {Observation of an {Electric} {Quadrupole} {Transition} in a {Negative} {Ion}: {Experiment} and {Theory}}, journal = {Phys. Rev. Lett.}, volume = {126}, number = {8}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, abstract = {The first direct experimental observation of an electric quadrupole (E2) absorption transition between bound states of an atomic negative ion has been made. The transition was observed in the negative ion of bismuth by resonant (1 + 1) photon detachment from Bi- via P-3(2) -{\textgreater} P-3(0) excitation. The E2 transition properties were completely independently calculated using a hybrid theoretical approach to account for the strong multilevel electron interactions and relativistic effects. The experimental and ab initio theoretical results are in excellent agreement, providing valuable new insight into this complex system and forbidden transitions in negative ions more generally.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.126.083001}, author = {Walter, C. W. and Spielman, S. E. and Ponce, R. and Gibson, N. D. and Yukich, J. N. and Cheung, C. and Safronova, M. S.} } @article {19231, title = {Optimal control for quantum detectors}, journal = {npj Quantum Information}, volume = {7}, year = {2021}, month = {03/2021}, abstract = {Quantum systems are promising candidates for sensing of weak signals as they can be highly sensitive to external perturbations, thus providing excellent performance when estimating parameters of external fields. However, when trying to detect weak signals that are hidden by background noise, the signal-to-noise ratio is a more relevant metric than raw sensitivity. We identify, under modest assumptions about the statistical properties of the signal and noise, the optimal quantum control to detect an external signal in the presence of background noise using a quantum sensor. Interestingly, for white background noise, the optimal solution is the simple and well-known spin-locking control scheme. Using numerical techniques, we further generalize these results to the case of background noise with a Lorentzian spectrum. We show that for increasing correlation time, pulse based sequences, such as CPMG, are also close to the optimal control for detecting the signal, with the crossover dependent on the signal frequency. These results show that an optimal detection scheme can be easily implemented in near-term quantum sensors without the need for complicated pulse shaping.

}, doi = {10.1038/s41534-021-00383-5}, url = {https://doi.org/10.1038/s41534-021-00383-5}, author = {Paraj Titum and Kevin Schultz and Alireza Seif and Gregory Quiroz and B. D. Clader} } @article {brady_optimal_2021, title = {Optimal {Protocols} in {Quantum} {Annealing} and {Quantum} {Approximate} {Optimization} {Algorithm} {Problems}}, journal = {Phys. Rev. Lett.}, volume = {126}, number = {7}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {feb}, abstract = {Quantum annealing (QA) and the quantum approximate optimization algorithm (QAOA) are two special cases of the following control problem: apply a combination of two Hamiltonians to minimize the energy of a quantum state. Which is more effective has remained unclear. Here we analytically apply the framework of optimal control theory to show that generically, given a fixed amount of time, the optimal procedure has the pulsed (or {\textquotedblleft}bang-bang{\textquotedblright}) structure of QAOA at the beginning and end but can have a smooth annealing structure in between. This is in contrast to previous works which have suggested that bang-bang (i.e., QAOA) protocols are ideal. To support this theoretical work, we carry out simulations of various transverse field Ising models, demonstrating that bang-anneal-bang protocols are more common. The general features identified here provide guideposts for the nascent experimental implementations of quantum optimization algorithms.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.126.070505}, author = {Brady, Lucas T. and Baldwin, Christopher L. and Bapat, Aniruddha and Kharkov, Yaroslav and Gorshkov, V, Alexey} } @article {safronova_predicting_2021, title = {Predicting quasibound states of negative ions: {La}- as a test case}, journal = {Phys. Rev. A}, volume = {103}, number = {2}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {feb}, abstract = {We demonstrated the accurate prediction of a quasibound spectrum of a negative ion using a high-precision theoretical approach. We used La as a test case due to a recent experiment that measured energies of 11 resonances in its photodetachment spectrum attributed to transitions to quasibound states [Phys. Rev. A 102, 042812 (2020)]. We identified all of the observed resonances and predicted one more peak just outside the range of the prior experiment. Following the theoretical prediction, the peak was observed at the predicted wavelength, validating the identification. The same approach is applicable to a wide range of negative ions.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.103.022819}, author = {Safronova, M. S. and Cheung, C. and Kozlov, M. G. and Spielman, S. E. and Gibson, N. D. and Walter, C. W.} } @article {lu_proposal_2021, title = {Proposal for noise-free visible-telecom quantum frequency conversion through third-order sum and difference frequency generation}, journal = {Opt. Lett.}, volume = {46}, number = {2}, year = {2021}, note = {Place: 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA Publisher: OPTICAL SOC AMER Type: Article}, month = {jan}, pages = {222{\textendash}225}, abstract = {Quantum frequency conversion (QFC) between the visible and telecom is a key to connect quantum memories in fiber-based quantum networks. Current methods for linking such widely separated frequencies, such as sum/difference frequency generation and four-wave mixing Bragg scattering, are prone to broadband noise generated by the pump laser(s). To address this issue, we propose to use third-order sum/difference frequency generation (TSFG/TDFG) for an upconversion/downconversion QFC interface. In this process, two long wavelength pump photons combine their energy and momentum to mediate frequency conversion across the large spectral gap between the visible and telecom bands, which is particularly beneficial from the noise perspective. We show that waveguide-coupled silicon nitride microring resonators can be designed for efficient QFC between 606 and 1550 nm via a 1990 nm pump through TSFG/TDFG. We simulate the device dispersion and coupling, and from the simulated parameters, estimate that the frequency conversion can be efficient ({\textgreater}80\%) at 50 mW pump power. Our results suggest that microresonator TSFG/TDFG is promising for compact, scalable, and low-power QFC across large spectral gaps. (C) 2021 Optical Society of America}, issn = {0146-9592}, doi = {10.1364/OL.412602}, author = {Lu, Xiyuan and Moille, Gregory and Rao, Ashutosh and Srinivasan, Kartik} } @article {niroula_quantum_2021, title = {A quantum algorithm for string matching}, journal = {npj Quantum Inform.}, volume = {7}, number = {1}, year = {2021}, note = {Place: HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY Publisher: NATURE RESEARCH Type: Article}, month = {feb}, abstract = {Algorithms that search for a pattern within a larger data-set appear ubiquitously in text and image processing. Here, we present an explicit, circuit-level implementation of a quantum pattern-matching algorithm that matches a search string (pattern) of length M inside a longer text of length N. Our algorithm has a time complexity of (O) over tilde root N, while the space complexity remains modest at O(N+ M). We report the quantum gate counts relevant for both pre-fault-tolerant and fault-tolerant regimes.}, doi = {10.1038/s41534-021-00369-3}, author = {Niroula, Pradeep and Nam, Yunseong} } @article {norrgard_quantum_2021, title = {Quantum blackbody thermometry}, journal = {New J. Phys.}, volume = {23}, number = {3}, year = {2021}, note = {Place: TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND Publisher: IOP PUBLISHING LTD Type: Article}, month = {mar}, abstract = {Blackbody radiation sources are calculable radiation sources that are frequently used in radiometry, temperature dissemination, and remote sensing. Despite their ubiquity, blackbody sources and radiometers have a plethora of systematics. We envision a new, primary route to measuring blackbody radiation using ensembles of polarizable quantum systems, such as Rydberg atoms and diatomic molecules. Quantum measurements with these exquisite electric field sensors could enable active feedback, improved design, and, ultimately, lower radiometric and thermal uncertainties of blackbody standards. A portable, calibration-free Rydberg-atom physics package could also complement a variety of classical radiation detector and thermometers. The successful merger of quantum and blackbody-based measurements provides a new, fundamental paradigm for blackbody physics.}, keywords = {blackbody radiation, laser cooling molecules, quantum metrology, Rydberg atoms}, issn = {1367-2630}, doi = {10.1088/1367-2630/abe8f5}, author = {Norrgard, Eric B. and Eckel, Stephen P. and Holloway, Christopher L. and Shirley, Eric L.} } @article {austin_quantum_2021, title = {Quantum critical dynamics in a spinor {Hubbard} model quantum simulator}, journal = {Commun. Phys.}, volume = {4}, number = {1}, year = {2021}, note = {Place: HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY Publisher: NATURE RESEARCH Type: Article}, month = {mar}, abstract = {Three-dimensional (3D) strongly correlated many-body systems, especially their dynamics across quantum phase transitions, are prohibitively difficult to be numerically simulated. We experimentally demonstrate that such complex many-body dynamics can be efficiently studied in a 3D spinor Bose-Hubbard model quantum simulator, consisting of antiferromagnetic spinor Bose-Einstein condensates confined in cubic optical lattices. We find dynamics and scaling effects beyond the scope of existing theories at superfluid-insulator quantum phase transitions, and highlight spin populations as a good observable to probe the quantum critical dynamics. Our data indicate that the scaling exponents are independent of the nature of the quantum phase transitions. We also conduct numerical simulations in lower dimensions using time-dependent Gutzwiller approximations, which qualitatively describe our observations. Three-dimensional (3D) strongly correlated many-body systems and their dynamics across quantum phase transitions pose a challenge when it comes to numerical simulations. The authors experimentally demonstrated that such many-body dynamics can be efficiently studied in a 3D spinor Bose-Hubbard model quantum simulator, and observed dynamics and scaling effects beyond the scope of existing theories at superfluid-insulator quantum phase transitions.}, issn = {2399-3650}, doi = {10.1038/s42005-021-00562-y}, author = {Austin, Jared O. and Chen, Zihe and Shaw, Zachary N. and Mahmud, Khan W. and Liu, Yingmei} } @article {poniatowski_resistivity_2021, title = {Resistivity saturation in an electron-doped cuprate}, journal = {Phys. Rev. B}, volume = {103}, number = {2}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jan}, abstract = {We report the observation of resistivity saturation in lightly doped (x = 0.08) as-grown samples of the electron-doped cuprate La2-xCexCuO4. The saturation occurs at resistivity values roughly consistent with the phenomenological Mott-Ioffe-Regel criterion once the low effective carrier density of these materials is included in the analysis. These results imply that, at least for light doping, the high-temperature metallic phase of these materials is not necessarily strange and may be understood as simply a low-density metal.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.103.L020501}, author = {Poniatowski, Nicholas R. and Sarkar, Tarapada and Das Sarma, Sankar and Greene, Richard L.} } @article {osborn_reversible_2021, title = {Reversible {Fluxon} {Logic} {With} {Optimized} {CNOT} {Gate} {Components}}, journal = {IEEE Trans. Appl. Supercond.}, volume = {31}, number = {2}, year = {2021}, note = {Place: 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA Publisher: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC Type: Article}, month = {mar}, abstract = {Reversible logic gates were previously implemented in superconducting circuits as adiabatic-reversible gates, which are powered with a sufficiently slow clock. In contrast, we are studying ballistic-reversible gates, where fluxons serve to both encode the information and power the gates. No power is applied to the gate apart from the energy of the input fluxons, and the two possible flux polarities represent the bit states. Undamped long Josephson junctions (LJJs), where fluxons move at practically constant speed from inertia, form the input and output channels of the gates. LJJs are connected in the gates by circuit interfaces, which are designed to allow the ballistic scattering from input to output fluxon states, using the temporary excitation of a localized mode. The duration of the resonant scattering determines the operation time of the gate, approximately a few Josephson plasma periods. Due to the coherent conversions between fluxon and localized modes, the ballistic gates can be very efficient: In our simulations, only a few percent of the fluxon{\textquoteright}s energy are dissipated in the gate operation. Ballistic-reversible gates can be combined with other nonballistic gate circuits to extend the range of gate functionalities. Here, we describe how the CNOT can be built as a structure that includes the Identity-else-Same-gives-NOT (IDSN) and store-and-launch (SNL) gates. The IDSN is a 2-b ballistic gate, which we describe and analyze in terms of equivalent 1-b circuits. The SNL is a clocking gate, which allows the storage of a bit and the clocked launch of a fluxon on a bit-state-dependent output path. In the CNOT, the SNL gates provide the necessary routing and fluxon synchronization for the input to the IDSN gate.

}, keywords = {Ballistic signaling, fluxons, power efficient, reversible computing, superconducting logic circuits}, issn = {1051-8223}, doi = {10.1109/TASC.2020.3035344}, author = {Osborn, Kevin D. and Wustmann, Waltraut} } @article {shivam_studying_2021, title = {Studying {Viral} {Populations} with {Tools} from {Quantum} {Spin} {Chains}}, journal = {J. Stat. Phys.}, volume = {182}, number = {2}, year = {2021}, note = {Place: ONE NEW YORK PLAZA, SUITE 4600, NEW YORK, NY, UNITED STATES Publisher: SPRINGER Type: Article}, month = {feb}, abstract = {We study Eigen{\textquoteright}s model of quasi-species (Eigen in Selforganization of matter and the evolution of biological macromolecules. Naturwissenschaften 58(10):465, 1971), characterized by sequences that replicate with a specified fitness and mutate independently at single sites. The evolution of the population vector in time is then closely related to that of quantum spins in imaginary time. We employ multiple perspectives and tools from interacting quantum systems to examine growth and collapse of realistic viral populations, specifically considering excessive mutations in certain HIV proteins. All approaches used, including the simplest perturbation theory, give consistent results.

}, keywords = {Biological evolution, HIV, Quantum spin chains}, issn = {0022-4715}, doi = {10.1007/s10955-021-02716-2}, author = {Shivam, Saumya and Baldwin, Christopher L. and Barton, John and Kardar, Mehran and Sondhi, S. L.} } @article {liu_synthesis_2021, title = {Synthesis of {Narrow} {SnTe} {Nanowires} {Using} {Alloy} {Nanoparticles}}, journal = {ACS Appl. Electron. Mater.}, volume = {3}, number = {1}, year = {2021}, note = {Place: 1155 16TH ST, NW, WASHINGTON, DC 20036 USA Publisher: AMER CHEMICAL SOC Type: Article}, month = {jan}, pages = {184{\textendash}191}, abstract = {Topological crystalline insulator tin telluride (SnTe) provides a rich playground to examine interactions of correlated electronic states, such as ferroelectricity, topological surface states, and superconductivity. The study of SnTe nanowires may lead to even richer physics owing to the one-dimensional (1D) confinement effect and an increased contribution from the topological surface states. Thus, for transport measurements, SnTe nanowires must be synthesized with reduced diameters and high crystalline quality to ensure 1D confinement and phase coherence of the topological surface electrons. This study reports a facile growth method to produce narrow SnTe nanowires with a high yield using alloy nanoparticles as growth catalysts. The average diameter of the SnTe nanowires grown using alloy nanoparticles is 85 nm, nearly a factor of three reduction compared to the average diameter of 240 nm when using gold nanoparticles as growth catalysts. Transport measurements reveal the effect of the nanowire diameter on the residual resistance ratio and magnetoresistance. Particularly, the ferroelectric transition temperature for SnTe evolves systematically with the nanowire diameter. In situ cryogenic cooling of narrow SnTe nanowires in a transmission electron microscope directly reveals the cubic to rhombohedral structural transition, which is associated with the ferroelectric transition. Thus, these narrow SnTe nanowires represent a model system to study electronic states arising from 1D confinement, such as 1D topological superconductivity and potential multiband superconductivity.

}, keywords = {ferroelectric transition, Nanowires, tin telluride, topological crystalline insulators, vapor-liquid-solid growth}, doi = {10.1021/acsaelm.0c00740}, author = {Liu, Pengzi and Han, Hyeuk Jin and Wei, Julia and Hynek, David and Hart, James L. and Han, Myung Geun and Trimble, Christie Jordan and Williams, James and Zhu, Yimei and Cha, Judy J.} } @article {ahn_theory_2021, title = {Theory of anisotropic plasmons}, journal = {Phys. Rev. B}, volume = {103}, number = {4}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jan}, abstract = {We develop the complete theory for the collective plasmon modes of an interacting electron system in the presence of explicit mass (or velocity) anisotropy in the corresponding noninteracting situation, with the effective Fermi velocity being different along different axes. Such effective mass anisotropy is common in solid state materials (e.g., silicon or germanium), where the Fermi surface is often not spherical. We find that the plasmon dispersion itself develops significant anisotropy in such systems, and the commonly used isotropic approximation of using a density of states or optical effective mass does not work for the anisotropic system. We predict a qualitatively new phenomenon in anisotropic systems with no corresponding isotropic analog, where the plasmon mode along one direction decays into electron-hole pairs through Landau damping while the mode remains undamped and stable along a different direction.

}, issn = {2469-9950}, doi = {10.1103/PhysRevB.103.L041303}, author = {Ahn, Seongjin and Sankar Das Sarma} } @article {childs_theory_2021, title = {Theory of {Trotter} {Error} with {Commutator} {Scaling}}, journal = {Phys. Rev. X}, volume = {11}, number = {1}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {feb}, abstract = {The Lie-Trotter formula, together with its higher-order generalizations, provides a direct approach to decomposing the exponential of a sum of operators. Despite significant effort, the error scaling of such product formulas remains poorly understood. We develop a theory of Trotter error that overcomes the limitations of prior approaches based on truncating the Baker-Campbell-Hausdorff expansion. Our analysis directly exploits the commutativity of operator summands, producing tighter error bounds for both real- and imaginary-time evolutions. Whereas previous work achieves similar goals for systems with geometric locality or Lie-algebraic structure, our approach holds, in general. We give a host of improved algorithms for digital quantum simulation and quantum Monte Carlo methods, including simulations of second-quantized plane-wave electronic structure, k-local Hamiltonians, rapidly decaying power-law interactions, clustered Hamiltonians, the transverse field Ising model, and quantum ferromagnets, nearly matching or even outperforming the best previous results. We obtain further speedups using the fact that product formulas can preserve the locality of the simulated system. Specifically, we show that local observables can be simulated with complexity independent of the system size for power-law interacting systems, which implies a Lieb-Robinson bound as a by-product. Our analysis reproduces known tight bounds for first- and second-order formulas. Our higher-order bound overestimates the complexity of simulating a one-dimensional Heisenberg model with an even-odd ordering of terms by only a factor of 5, and it is close to tight for power-law interactions and other orderings of terms. This result suggests that our theory can accurately characterize Trotter error in terms of both asymptotic scaling and constant prefactor.

}, issn = {2160-3308}, doi = {10.1103/PhysRevX.11.011020}, author = {Childs, Andrew M. and Su, Yuan and Tran, Minh C. and Wiebe, Nathan and Zhu, Shuchen} } @article {pan_three-terminal_2021, title = {Three-terminal nonlocal conductance in {Majorana} nanowires: {Distinguishing} topological and trivial in realistic systems with disorder and inhomogeneous potential}, journal = {Phys. Rev. B}, volume = {103}, number = {1}, year = {2021}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jan}, abstract = {We develop a theory for the three-terminal nonlocal conductance in Majorana nanowires as existing in the superconductor-semiconductor hybrid structures in the presence of superconducting proximity, spin-orbit coupling, and Zeeman splitting. The key question addressed is whether such nonlocal conductance can decisively distinguish between trivial and topological Majorana scenarios in the presence of chemical potential inhomogeneity and random impurity disorder. We calculate the local electrical as well as nonlocal electrical and thermal conductance of the pristine nanowire (good zero-bias conductance peaks), the nanowire in the presence of quantum dots and inhomogeneous potential (bad zero-bias conductance peaks), and the nanowire in the presence of large disorder (ugly zero-bias conductance peaks). The local conductance by itself is incapable of distinguishing the trivial states from the topological states since zero-bias conductance peaks are generic in the presence of disorder and inhomogeneous potential. The nonlocal conductance, which in principle is capable of providing the bulk gap closing and reopening information at the topological quantum phase transition, is found to be far too weak in magnitude to be particularly useful in the presence of disorder and inhomogeneous potential. Therefore, we focus on the question of whether the combination of the local, nonlocal electrical, and thermal conductance can separate the good, bad, and ugly zero-bias conductance peaks in finite-length wires. Our paper aims to provide a guide to future experiments, and we conclude that a combination of all three measurements would be necessary for a decisive demonstration of topological Majorana zero modes in nanowires-positive signals corresponding to just one kind of measurements are likely to be false positives arising from disorder and inhomogeneous potential.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.103.014513}, author = {Pan, Haining and Sau, Jay D. and Das Sarma, S.} } @article {19181, title = {Topological features without a lattice in Rashba spin-orbit coupled atoms}, journal = {Nature Communications}, volume = {12}, year = {2021}, month = {01/2021}, abstract = {Topological order can be found in a wide range of physical systems, from crystalline solids, photonic meta-materials and even atmospheric waves to optomechanic, acoustic and atomic systems. Topological systems are a robust foundation for creating quantized channels for transporting electrical current, light, and atmospheric disturbances. These topological effects are quantified in terms of integer-valued {\textquoteleft}invariants{\textquoteright}, such as the Chern number, applicable to the quantum Hall effect, or the\ Z2Z2\ invariant suitable for topological insulators. Here, we report the engineering of Rashba spin-orbit coupling for a cold atomic gas giving non-trivial topology, without the underlying crystalline structure that conventionally yields integer Chern numbers. We validated our procedure by spectroscopically measuring both branches of the Rashba dispersion relation which touch at a single Dirac point. We then measured the quantum geometry underlying the dispersion relation using matter-wave interferometry to implement a form of quantum state tomography, giving a Berry{\textquoteright}s phase with magnitude\ *Ï€*. This implies that opening a gap at the Dirac point would give two dispersions (bands) each with half-integer Chern number, potentially implying new forms of topological transport.

Sources of quantum light, in particular correlated photon pairs that are indistinguishable for all degrees of freedom, are the fundamental resource for photonic quantum computation and simulation. Although such sources have been recently realized using integrated photonics, they offer limited ability to tune the spectral and temporal correlations between generated photons because they rely on a single component, such as a ring resonator. Here, we demonstrate a tunable source of indistinguishable photon pairs using dual-pump spontaneous four-wave mixing in a topological system comprising a two-dimensional array of resonators. We exploit the linear dispersion of the topological edge states to tune the spectral bandwidth (by about 3.5{\texttimes}), and thereby, to tune quantum interference between generated photons by tuning the two pump frequencies. We demonstrate energy-time entanglement and, using numerical simulations, confirm the topological robustness of our source. Our results could lead to tunable, frequency-multiplexed quantum light sources for photonic quantum technologies.

}, doi = {10.1038/s41566-021-00810-1}, url = {https://doi.org/10.1038/s41566-021-00810-1}, author = {Sunil Mittal and Venkata Vikram Orre and Elizabeth A. Goldschmidt and Mohammad Hafezi} } @article {19291, title = {Tunable Three-Body Loss in a Nonlinear Rydberg Medium}, journal = {Phys. Rev. Lett.}, volume = {126}, year = {2021}, month = {Apr}, pages = {173401}, abstract = {Long-range Rydberg interactions, in combination with electromagnetically induced transparency (EIT), give rise to strongly interacting photons where the strength, sign, and form of the interactions are widely tunable and controllable. Such control can be applied to both coherent and dissipative interactions, which provides the potential for generating novel few-photon states. Recently it has been shown that Rydberg-EIT is a rare system in which three-body interactions can be as strong or stronger than two-body interactions. In this work, we study three-body scattering loss for Rydberg-EIT in a wide regime of single and two-photon detunings. Our numerical simulations of the full three-body wave function and analytical estimates based on Fermi{\textquoteright}s golden rule strongly suggest that the observed features in the outgoing photonic correlations are caused by the resonant enhancement of the three-body losses.

}, doi = {10.1103/PhysRevLett.126.173401}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.126.173401}, author = {Ornelas-Huerta, D. P. and Bienias, Przemyslaw and Craddock, Alexander N. and Gullans, Michael J. and Hachtel, Andrew J. and Kalinowski, Marcin and Lyon, Mary E. and Gorshkov, Alexey V. and Rolston, S. L. and Porto, J. V.} } @article {carney_ultralight_2021, title = {Ultralight dark matter detection with mechanical quantum sensors}, journal = {New J. Phys.}, volume = {23}, number = {2}, year = {2021}, note = {Place: TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND Publisher: IOP PUBLISHING LTD Type: Article}, month = {feb}, abstract = {We consider the use of quantum-limited mechanical force sensors to detect ultralight (sub-meV) dark matter (DM) candidates which are weakly coupled to the standard model. We show that mechanical sensors with masses around or below the milligram scale, operating around the standard quantum limit, would enable novel searches for DM with natural frequencies around the kHz scale. This would complement existing strategies based on torsion balances, atom interferometers, and atomic clock systems.}, keywords = {dark matter, Optomechanics, quantum sensing}, issn = {1367-2630}, doi = {10.1088/1367-2630/abd9e7}, author = {Carney, Daniel and Hook, Anson and Liu, Zhen and Taylor, Jacob M. and Zhao, Yue} } @article {zhang_van_2021, title = {Van der {Waals} heterostructure polaritons with moire-induced nonlinearity}, journal = {Nature}, volume = {591}, number = {7848}, year = {2021}, note = {Place: HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY Publisher: NATURE RESEARCH Type: Article}, month = {mar}, pages = {61+}, abstract = {Controlling matter-light interactions with cavities is of fundamental importance in modern science and technology(1). This is exemplified in the strong-coupling regime, where matter-light hybrid modes form, with properties that are controllable by optical-wavelength photons(2,3). By contrast, matter excitations on the nanometre scale are harder to access. In two-dimensional van der Waals heterostructures, a tunable moire lattice potential for electronic excitations may form(4), enabling the generation of correlated electron gases in the lattice potentials(5-9). Excitons confined in moire lattices have also been reported(10,11), but no cooperative effects have been observed and interactions with light have remained perturbative(12-15). Here, by integrating MoSe2-WS2 heterobilayers in a microcavity, we establish cooperative coupling between moire-lattice excitons and microcavity photons up to the temperature of liquid nitrogen, thereby integrating versatile control of both matter and light into one platform. The density dependence of the moire polaritons reveals strong nonlinearity due to exciton blockade, suppressed exciton energy shift and suppressed excitation-induced dephasing, all of which are consistent with the quantum confined nature of the moire excitons. Such a moire polariton system combines strong nonlinearity and microscopic-scale tuning of matter excitations using cavity engineering and long-range light coherence, providing a platform with which to study collective phenomena from tunable arrays of quantum emitters.}, issn = {0028-0836}, doi = {10.1038/s41586-021-03228-5}, author = {Zhang, Long and Wu, Fengcheng and Hou, Shaocong and Zhang, Zhe and Chou, Yu-Hsun and Watanabe, Kenji and Taniguchi, Takashi and Forrest, Stephen R. and Deng, Hui} } @article {huang_4d_2020, title = {{4D} beyond-cohomology topological phase protected by {C}-2 symmetry and its boundary theories}, journal = {Phys. Rev. Res.}, volume = {2}, number = {3}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {aug}, abstract = {We study bosonic symmetry-protected topological (SPT) phases with C-2 rotational symmetry in four spatial dimensions which is not captured by the group cohomology classification. By using the topological crystal approach, we show that the topological crystalline state of this SPT phase is given by placing an E-8 state on the two-dimensional rotational invariant plane, which provides a simple physical picture of this phase. Based on this understanding, we show that a variant of QED in four dimensions (QED(4)) with charge-1 and charge-3 Dirac fermions is a field theoretical description of the three-dimensional boundary. We also discuss the connection to a symmetric gapped boundary with topological order and its anomalous signature.

}, doi = {10.1103/PhysRevResearch.2.033236}, author = {Huang, Sheng-Jie} } @article {bulmash_absolute_2020, title = {Absolute anomalies in (2+1){D} symmetry-enriched topological states and exact (3+1){D} constructions}, journal = {Phys. Rev. Res.}, volume = {2}, number = {4}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {oct}, abstract = {Certain patterns of symmetry fractionalization in (2+1)-dimensional [(2+1)D] topologically ordered phases of matter can be anomalous, which means that they possess an obstruction to being realized in purely (2+1)D. In this paper we demonstrate how to compute the anomaly for symmetry-enriched topological states of bosons in complete generality. We demonstrate how, given any unitary modular tensor category (UMTC) and symmetry fractionalization class for a global symmetry group G, one can define a (3+1)-dimensional [(3+1)D] topologically invariant path integral in terms of a state sum for a G-symmetry-protected topological (SPT) state. We present an exactly solvable Hamiltonian for the system and demonstrate explicitly a (2+1)D G-symmetric surface termination that hosts deconfined anyon excitations described by the given UMTC and symmetry fractionalization class. We present concrete algorithms that can be used to compute anomaly indicators in general. Our approach applies to general symmetry groups, including anyon-permuting and antiunitary symmetries. In addition to providing a general way to compute the anomaly, our result also shows, by explicit construction, that every symmetry fractionalization class for any UMTC can be realized at the surface of a (3+1)D SPT state. As a by-product, this construction also provides a way of explicitly seeing how the algebraic data that defines symmetry fractionalization in general arises in the context of exactly solvable models. In the case of unitary orientation-preserving symmetries, our results can also be viewed as providing a method to compute the H-4(G, U(1)) obstruction that arises in the theory of G-crossed braided tensor categories, for which no general method has been presented to date.}, doi = {10.1103/PhysRevResearch.2.043033}, author = {Bulmash, Daniel and Barkeshli, Maissam} } @article { ISI:000513256600002, title = {Accessing ratios of quantized resistances in graphene p-n junction devices using multiple terminals}, journal = {AIP Adv.}, volume = {10}, number = {2}, year = {2020}, month = {FEB 1}, pages = {025112}, publisher = {AMER INST PHYSICS}, type = {Article}, abstract = {The utilization of multiple current terminals on millimeter-scale graphene p-n junction devices has enabled the measurement of many atypical, fractional multiples of the quantized Hall resistance at the v = 2 plateau (R-H approximate to 12 906 Omega). These fractions take the form a/bR(H) and can be determined both analytically and by simulations. These experiments validate the use of either the LTspice circuit simulator or the analytical framework recently presented in similar work. Furthermore, the production of several devices with large-scale junctions substantiates the approach of using simple ultraviolet lithography to obtain junctions of sufficient sharpness. (C) 2020 Author(s).}, doi = {10.1063/1.5138901}, author = {Patel, Dinesh and Marzano, Martina and Liu, I, Chieh- and Hill, Heather M. and Kruskopf, Mattias and Jin, Hanbyul and Hu, Jiuning and Newell, David B. and Liang, Chi-Te and Elmquist, Randolph and Rigosi, Albert F.} } @article { ISI:000528518000008, title = {Accurate Prediction of Clock Transitions in a Highly Charged Ion with Complex Electronic Structure}, journal = {Phys. Rev. Lett.}, volume = {124}, number = {16}, year = {2020}, month = {APR 24}, pages = {163001}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We develop a broadly applicable approach that drastically increases the ability to predict the properties of complex atoms accurately. We apply it to the case of Ir-17(+), which is of particular interest for the development of novel atomic clocks with a high sensitivity to the variation of the fine-structure constant and to dark matter searches. In general, clock transitions are weak and very difficult to identify without accurate theoretical predictions. In the case of Ir-17(+), even stronger electric-dipole (El) transitions have eluded observation despite years of effort, raising the possibility that the theoretical predictions are grossly wrong. In this work, we provide accurate predictions of the transition wavelengths and E1 transition rates for Ir-17(+). Our results explain the lack of observations of the E1 transitions and provide a pathway toward the detection of clock transitions. The computational advances we demonstrate in this work are widely applicable to most elements in the periodic table and will allow us to solve numerous problems in atomic physics, astrophysics, and plasma physics.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.124.163001}, author = {Cheung, C. and Safronova, M. S. and Porsev, S. G. and Kozlov, M. G. and Tupitsyn, I. I. and Bondarev, I. A.} } @article { ISI:000533306300001, title = {Analysing quantized resistance behaviour in graphene Corbino p-n junction devices}, journal = {J. Phys. D-Appl. Phys.}, volume = {53}, number = {27}, year = {2020}, month = {JUL 1}, pages = {275301}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {Just a few of the promising applications of graphene Corbino pnJ devices include two-dimensional Dirac fermion microscopes, custom programmable quantized resistors, and mesoscopic valley filters. In some cases, device scalability is crucial, as seen in fields like resistance metrology, where graphene devices are required to accommodate currents of the order 100 mu A to be compatible with existing infrastructure. However, fabrication of these devices still poses many difficulties. In this work, unusual quantized resistances are observed in epitaxial graphene Corbino p-n junction devices held at the nu=2We present a theoretical study of single-particle and many-body properties of twisted bilayer WSe2. For single-particle physics, we calculate the band topological phase diagram and electron local density of states (LDOS), which are found to be correlated. By comparing our theoretical LDOS with those measured by scanning tunneling microscopy, we comment on the possible topological nature of the first moire valence band. For many-body physics, we construct a generalized Hubbard model on a triangular lattice based on the calculated single-particle moire bands. We show that a layer potential difference, arising, for example, from an applied electric field, can drastically change the noninteracting moire bands, tune the spin-orbit coupling in the Hubbard model, control the charge excitation gap of the Mott insulator at half-filling, and generate an effective Dzyaloshinskii-Moriya interaction in the effective Heisenberg model for the Mott insulator. Our theoretical results agree with transport experiments on the same system in several key aspects, and establish twisted bilayer WSe2 as a highly tunable system for studying and simulating strongly correlated phenomena in the Hubbard model.

}, doi = {10.1103/PhysRevResearch.2.033087}, author = {Pan, Haining and Wu, Fengcheng and Das Sarma, Sankar} } @article { ISI:000570300500002, title = {Beyond spontaneous emission: Giant atom bounded in the continuum}, journal = {Phys. Rev. A}, volume = {102}, number = {3}, year = {2020}, month = {SEP 8}, pages = {033706}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The quantum coupling of individual superconducting qubits to microwave photons leads to remarkable experimental opportunities. Here we consider the phononic case where the qubit is coupled to an electromagnetic surface acoustic wave antenna that enables supersonic (electromagnetic) propagation of the qubit oscillations. This can be considered as a giant atom that is many phonon wavelengths long. We study an exactly solvable toy model that captures these effects, and find that this non-Markovian giant atom has a suppressed relaxation, so long as an effective vacuum coupling exists between a qubit excitation and a localized wave packet of sound, even in the absence of a cavity for the sound waves. Finally, we consider practical implementations of these ideas in current surface acoustic wave devices.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.102.033706}, author = {Guo, Shangjie and Wang, Yidan and Purdy, Thomas and Taylor, Jacob} } @article { ISI:000565826800008, title = {Braiding photonic topological zero modes}, journal = {Nat. Phys.}, volume = {16}, number = {9}, year = {2020}, month = {SEP}, pages = {989+}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {A remarkable property of quantum mechanics in two-dimensional space is its ability to support {\textquoteleft}anyons{\textquoteright}, particles that are neither fermions nor bosons. Theory predicts that these exotic excitations can exist as bound states confined near topological defects, such as Majorana zero modes trapped in vortices in topological superconductors. Intriguingly, in the simplest cases the non-trivial phase that arises when such defects are {\textquoteleft}braided{\textquoteright} around one another is not intrinsically quantum mechanical; instead, it can be viewed as a manifestation of the geometric (Pancharatnam-Berry) phase in wave mechanics, which makes possible the simulation of such phenomena in classical systems. Here, we report the experimental measurement of the geometric phase owing to such a braiding process. These measurements are obtained with an interferometer constructed from highly tunable two-dimensional arrays of photonic waveguides. Our results introduce photonic lattices as a versatile platform for the experimental study of topological defects and their braiding, and complement ongoing efforts in the study of solid-state systems and cold atomic gases. The non-zero geometric phase acquired by the braiding of vortex modes in photonic waveguide lattices demonstrates their potential to serve as a platform for the study of both Abelian and non-Abelian braiding in bosonic systems.}, issn = {1745-2473}, doi = {10.1038/s41567-020-1007-5},}, author = {Noh, Jiho and Schuster, Thomas and Iadecola, Thomas and Huang, Sheng and Wang, Mohan and Chen, Kevin P. and Chamon, Claudio and Rechtsman, Mikael C.} } @article {zhang_branching_2020, title = {Branching fractions for {P}-3/2 decays in {Ba}+}, journal = {Phys. Rev. A}, volume = {101}, number = {6}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jun}, abstract = {Branching fractions for decays from the P-3/2 level in B-138 at have been measured with a single laser-cooled ion. Decay probabilities to S-1/2, D-3/2, and D-5/2 are determined to be 0.741716(71), 0.028031(23), and 0.230253(61), respectively, which are an order-of-magnitude improvement over previous results. Our methodology only involves optical pumping and state detection, and is hence relatively free of systematic effects. Measurements are carried out in two different ways to check for consistency. Our analysis also includes a measurement of the D-5/2 lifetime, for which we obtain 30.14(40) s.}, issn = {1050-2947}, doi = {10.1103/PhysRevA.101.062515}, author = {Zhang, Zhiqiang and Arnold, K. J. and Chanu, S. R. and Kaewuam, R. and Safronova, M. S. and Barrett, M. D.} } @article { ISI:000548140000001, title = {Branching fractions for P-3/2 decays in Ba+}, journal = {Phys. Rev. A}, volume = {101}, number = {6}, year = {2020}, month = {JUN 24}, pages = {062515}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Branching fractions for decays from the P-3/2 level in B-138 at have been measured with a single laser-cooled ion. Decay probabilities to S-1/2, D-3/2, and D-5/2 are determined to be 0.741716(71), 0.028031(23), and 0.230253(61), respectively, which are an order-of-magnitude improvement over previous results. Our methodology only involves optical pumping and state detection, and is hence relatively free of systematic effects. Measurements are carried out in two different ways to check for consistency. Our analysis also includes a measurement of the D-5/2 lifetime, for which we obtain 30.14(40) s.}, issn = {1050-2947}, doi = {10.1103/PhysRevA.101.062515}, author = {Zhang, Zhiqiang and Arnold, K. J. and Chanu, S. R. and Kaewuam, R. and Safronova, M. S. and Barrett, M. D.} } @article {moille_broadband_2020, title = {Broadband resonator-waveguide coupling for efficient extraction of octave-spanning microcombs}, journal = {Opt. Lett.}, volume = {45}, number = {17}, year = {2020}, note = {Place: 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA Publisher: OPTICAL SOC AMER Type: Correction}, month = {sep}, pages = {4939}, issn = {0146-9592}, doi = {10.1364/OL.405775}, author = {Moille, Gregory and Li, Qing and Briles, Travis C. and Yu, Su-Peng and Drake, Tara and Lu, Xiyuan and Rao, Ashutosh and Westly, Daron and Papp, Scott B. and Srinivasan, Kartik} } @article { ISI:000550674500006, title = {Calculation of higher-order corrections to the light shift of the 5s(2) S-1(0)-5s5p P-3(0)o clock transition in Cd}, journal = {Phys. Rev. A}, volume = {102}, number = {1}, year = {2020}, month = {JUL 20}, pages = {012811}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {In the recent work by Yamaguchi et al. {[}Phys. Rev. Lett. 123, 113201 (2019)] Cd was identified as an excellent candidate for a lattice clock. Here, we carried out computations needed for further clock development and made an assessment of the higher-order corrections to the light shift of the 5s(2) S-1(0) -5s5p P-3(0)o clock transition. We carried out calculations of the magnetic dipole and electric quadrupole polarizabilities and linear and circular hyperpolarizabilities of the 5s(2) S-1(0) and 5s5p P-3(0)o clock states at the magic wavelength and estimated uncertainties of these quantities. We also evaluated the second-order Zeeman clock transition frequency shift.}, issn = {1050-2947}, doi = {10.1103/PhysRevA.102.012811}, author = {Porsev, S. G. and Safronova, M. S.} } @article {raines_cavity_2020, title = {Cavity {Higgs} polaritons}, journal = {Phys. Rev. Res.}, volume = {2}, number = {1}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {feb}, abstract = {Motivated by the dramatic success of realizing cavity exciton-polariton condensation in experiment we consider the formation of polaritons from cavity photons and the amplitude or Higgs mode of a superconductor. Enabled by the recently predicted and observed supercurrent-induced linear coupling between these excitations and light, we find that hybridization between Higgs excitations in a disordered quasi-2D superconductor and resonant cavity photons can occur, forming Higgs-polariton states. This provides the potential for a new means to manipulate the superconducting state as well as the potential for novel photonic cavity circuit elements.}, doi = {10.1103/PhysRevResearch.2.013143}, author = {Raines, Zachary M. and Allocca, Andrew A. and Hafezi, Mohammad and Galitski, Victor M.} } @conference {barik_chiral_2020-1, title = {Chiral coupling of a quantum emitter in a topological photonic resonator}, booktitle = {2020 Conference on Lasers and Electro-Optics (CLEO)}, series = {Conference on {Lasers} and {Electro}-{Optics}}, year = {2020}, note = {Backup Publisher: IEEE ISSN: 2160-9020 Type: Proceedings Paper}, publisher = {IEEE}, organization = {IEEE}, address = {345 E 47TH ST, NEW YORK, NY 10017 USA}, abstract = {Here we demonstrate chiral light-matter interactions in a topological photonic crystal resonator. We achieve this by employing valley-Hall topological edge states to create a helical resonator at the interface of two topologically distinct regions. (C) 2020 The Author(s)

}, isbn = {978-1-943580-76-7}, author = {Barik, Sabyasachi and Karasahin, Aziz and Mittal, Sunil and Hafezi, Mohammad and Waks, Edo} } @article { ISI:000531732200005, title = {Chiral quantum optics using a topological resonator}, journal = {Phys. Rev. B}, volume = {101}, number = {20}, year = {2020}, month = {MAY 12}, pages = {205303}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Chiral nanophotonic components, such as waveguides and resonators coupled to quantum emitters, provide a fundamentally new approach to manipulate light-matter interactions. The recent emergence of topological photonics has provided a new paradigm to realize helical/chiral nanophotonic structures that are flexible in design and, at the same time, robust against sharp bends and disorder. Here we demonstrate such a topologically protected chiral nanophotonic resonator that is strongly coupled to a solid-state quantum emitter. Specifically, we employ the valley-Hall effect in a photonic crystal to achieve topological edge states at an interface between two topologically distinct regions. Our helical resonator supports two counterpropagating edge modes with opposite polarizations. We first show chiral coupling between the topological resonator and the quantum emitter such that the emitter emits preferably into one of the counterpropagating edge modes depending upon its spin. Subsequently, we demonstrate strong coupling between the resonator and the quantum emitter using resonant Purcell enhancement in the emission intensity by a factor of 3.4. Such chiral resonators could enable designing complex nanophotonic circuits for quantum information processing and studying novel quantum many-body dynamics.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.205303}, author = {Barik, Sabyasachi and Karasahin, Aziz and Mittal, Sunil and Waks, Edo and Hafezi, Mohammad} } @article {liu_circuit_2020, title = {Circuit complexity across a topological phase transition}, journal = {Phys. Rev. Res.}, volume = {2}, number = {1}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {mar}, abstract = {We use Nielsen{\textquoteright}s geometric approach to quantify the circuit complexity in a one-dimensional Kitaev chain across a topological phase transition. We find that the circuit complexities of both the ground states and nonequilibrium steady states of the Kitaev model exhibit nonanalytical behaviors at the critical points, and thus can be used to detect both equilibrium and dynamical topological phase transitions. Moreover, we show that the locality property of the real-space optimal Hamiltonian connecting two different ground states depends crucially on whether the two states belong to the same or different phases. This provides a concrete example of classifying different gapped phases using Nielsen{\textquoteright}s circuit complexity. We further generalize our results to a Kitaev chain with long-range pairing, and we discuss generalizations to higher dimensions. Our result opens up an avenue for using circuit complexity as a tool to understand quantum many-body systems.}, doi = {10.1103/PhysRevResearch.2.013323}, author = {Liu, Fangli and Whitsitt, Seth and Curtis, Jonathan B. and Lundgren, Rex and Titum, Paraj and Yang, Zhi-Cheng and Garrison, James R. and Gorshkov, V, Alexey} } @article { ISI:000564912400007, title = {Coherent optical nanotweezers for ultracold atoms}, journal = {Phys. Rev. A}, volume = {102}, number = {1}, year = {2020}, month = {JUL 7}, pages = {013306}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {There has been a recent surge of interest and progress in creating subwavelength free-space optical potentials for ultracold atoms. A key open question is whether geometric potentials, which are repulsive and ubiquitous in the creation of subwavelength free-space potentials, forbid the creation of narrow traps with long lifetimes. Here, we show that it is possible to create such traps. We propose two schemes for realizing subwavelength traps and demonstrate their superiority over existing proposals. We analyze the lifetime of atoms in such traps and show that long-lived bound states are possible. This work allows for subwavelength control and manipulation of ultracold matter, with applications in quantum chemistry and quantum simulation.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.102.013306}, author = {Bienias, P. and Subhankar, S. and Wang, Y. and Tsui, T-C and Jendrzejewski, F. and Tiecke, T. and Juzeliunas, G. and Jiang, L. and Rolston, S. L. and Porto, V, J. and Gorshkov, V, A.} } @article { ISI:000510176900007, title = {Collective Excitations of Quantum Anomalous Hall Ferromagnets in Twisted Bilayer Graphene}, journal = {Phys. Rev. Lett.}, volume = {124}, number = {4}, year = {2020}, month = {JAN 30}, pages = {046403}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We present a microscopic theory for collective excitations of quantum anomalous Hall ferromagnets (QAHF) in twisted bilayer graphene. We calculate the spin magnon and valley magnon spectra by solving Bethe-Salpeter equations and verify the stability of QAHF. We extract the spin stiffness from the gapless spin wave dispersion and estimate the energy cost of a skyrmion-antiskyrmion pair, which is found to be comparable in energy with the Hartree-Fock gap. The valley wave mode is gapped, implying that the valley polarized state is more favorable compared to the valley coherent state. Using a nonlinear sigma model, we estimate the valley ordering temperature, which is considerably reduced from the mean-field transition temperature due to thermal excitations of valley waves.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.124.046403}, author = {Wu, Fengcheng and Das Sarma, Sankar} } @article {vu_collective_2020, title = {Collective ground states in small lattices of coupled quantum dots}, journal = {Phys. Rev. Res.}, volume = {2}, number = {2}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {apr}, abstract = {Motivated by recent developments on the fabrication and control of semiconductor-based quantum dots, we theoretically study a finite system of tunnel-coupled quantum dots with the electrons interacting through the long-range Coulomb interaction. When the interelectron separation is large and the quantum dot confinement potential is weak, the system behaves as an effective Wigner crystal with a period determined by the electron average density with considerable electron hopping throughout the system. For stronger periodic confinement potentials, however, the system makes a crossover to a Mott-type ground state where the electrons are completely localized at the individual dots with little interdot tunneling. In between these two phases, the system is essentially a strongly correlated electron liquid with intersite electron hopping constrained by strong Coulomb interaction. We characterize this Wigner-Mott-liquid quantum crossover with detailed numerical finite-size diagonalization calculations of the coupled interacting quantum dot system, showing that these phases can be smoothly connected by tuning the system parameters. Experimental feasibility of observing such a hopping-tuned Wigner-Mott-liquid crossover in currently available semiconductor quantum dots is discussed. In particular, we connect our theoretical results to recent quantum-dot-based quantum emulation experiments where a collective Coulomb blockade was demonstrated. We discuss realistic disorder effects on our theoretical findings. One conclusion of our work is that experiments must explore lower density quantum dot arrays in order to clearly observe the Wigner phase although the Mott-liquid crossover phenomenon should already manifest itself in the currently available quantum dot arrays. We also suggest a direct experimental electron density probe, such as atomic force microscopy or scanning tunneling microscopy, for a clear observation of the effective Wigner crystal phase.

}, doi = {10.1103/PhysRevResearch.2.023060}, author = {Vu, DinhDuy and Das Sarma, Sankar} } @article { ISI:000505979700006, title = {Collisions of room-temperature helium with ultracold lithium and the van der Waals bound state of HeLi}, journal = {Phys. Rev. A}, volume = {101}, number = {1}, year = {2020}, month = {JAN 6}, pages = {012702}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We have computed the thermally averaged total, elastic rate coefficient for the collision of a room-temperature helium atom with an ultracold lithium atom. This rate coefficient has been computed as part of the characterization of a cold-atom vacuum sensor based on laser-cooled Li-6 or Li-7 atoms that will operate in the ultrahigh-vacuum (p < 10(-6) Pa) and extreme-high-vacuum (p < 10(-10) Pa) regimes. The analysis involves computing the X (2) Sigma(+) HeLi Born-Oppenheimer potential followed by the numerical solution of the relevant radial Schrodinger equation. The potential is computed using a single-reference-coupled-cluster electronic-structure method with basis sets of different completeness in order to characterize our uncertainty budget. We predict that the rate coefficient for a 300 K helium gas and a 1 mu K Li gas is 1.467(13) x 10(-9) cm(3)/s for He-4 + Li-6 and 1.471(13) x 10(-9) cm(3)/s for He-4 + Li-7, where the numbers in parentheses are the one-standard-deviation uncertainties in the last two significant digits. We quantify the temperature dependence as well. Finally, we evaluate the s-wave scattering length and binding of the single van der Waals bound state of HeLi. We predict that this weakly bound level has a binding energy of -0.0064(43) x hc cm(-1) and -0.0122(67) x hc cm(-1) for He-4 + Li-6 and He-4 + Li-7, respectively. The calculated binding energy of He-4 + Li-7 is consistent with the sole experimental determination.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.101.012702}, author = {Makrides, Constantinos and Barker, Daniel S. and Fedchak, James A. and Scherschligt, Julia and Eckel, Stephen and Tiesinga, Eite} } @article { ISI:000507490800005, title = {Combining experiments and relativistic theory for establishing accurate radiative quantities in atoms: The lifetime of the P-2(3/2) state in Ca-40(+)}, journal = {Phys. Rev. A}, volume = {101}, number = {1}, year = {2020}, month = {JAN 14}, pages = {012509}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We report a precise determination of the lifetime of the (4p) P-2(3/2) state of Ca-40(+), tau(p3/2) = 6.639(42) ns, using a combination of measurements of the induced light shift and scattering rate on a single trapped ion. Good agreement with the result of a recent high-level theoretical calculation, 6.69(6) ns {[}M. S. Safronova et al., Phys. A 83, 012503 (2011)], but a 6-sigma discrepancy with the most precise previous experimental value, 6.924(19) ns {[}J. Jin et al., Phys. Rev. Lett. 70, 3213 (1993)], is found. To corroborate the consistency and accuracy of the new measurements, relativistically corrected ratios of reduced-dipole-matrix elements are used to directly compare our result with a recent result for the P-1/2 state, yielding a good agreement. The application of the present method to precise determinations of radiative quantities of molecular systems is discussed.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.101.012509}, author = {Meir, Ziv and Sinhal, Mudit and Safronova, Marianna S. and Willitsch, Stefan} } @article {oe_comparison_2020, title = {Comparison {Between} {NIST} {Graphene} and {AIST} {GaAs} {Quantized} {Hall} {Devices}}, journal = {IEEE Trans. Instrum. Meas.}, volume = {69}, number = {6, 1}, year = {2020}, note = {Place: 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA Publisher: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC Type: Article}, month = {jun}, pages = {3103{\textendash}3108}, abstract = {Several graphene quantized Hall resistance (QHR) devices manufactured at the National Institute of Standards and Technology (NIST) were compared with GaAs QHR devices and a 100-Omega standard resistor at the National Institute for Advanced Industrial Science and Technology (AIST). Measurements of a 100-Omega resistor with graphene QHR devices agreed within 5 n Omega/Omega of the values for a 100-Omega resistor obtained through GaAs measurements. The electron density of the graphene devices was adjusted at AIST to restore device properties such that operation was possible at low magnetic flux densities of 4-6 T. This adjustment was accomplished by a functionalization method utilized at NIST, allowing for consistent tunability of the graphene QHR devices with simple annealing. Such a method replaces older and less predictable methods for adjusting graphene for metrological suitability. The milestone results demonstrate the ease with which graphene can be used to make resistance comparison measurements among many National Metrology Institutes (NMIs).

}, keywords = {cryogenic current comparator, electron density, Epitaxial graphene (EG), quantized Hall resistance (QHR), standard resistor}, issn = {0018-9456}, doi = {10.1109/TIM.2019.2930436}, author = {Oe, Takehiko and Rigosi, Albert F. and Kruskopf, Mattias and Wu, Bi-Yi and Lee, Hsin-Yen and Yang, Yanfei and Elmquist, Randolph E. and Kaneko, Nobu-hisa and Jarrett, Dean G.} } @article { ISI:000571724100001, title = {A comparison of g((1)) (tau), g((3/2))(tau), and g((2))(tau) for radiation from harmonic oscillators in Brownian motion with a coherent background}, journal = {Phys. Scr.}, volume = {95}, number = {10}, year = {2020}, month = {OCT}, pages = {104001}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {We compare the field-fieldg((1))(tau), intensity-fieldg((3/2))(tau), and intensity-intensityg((2))(tau) correlation functions for models that are of relevance in astrophysics. We obtain expressions for the general case of a chaotic radiation, where the amplitude is Rician based on a model with an ensemble of harmonic oscillators in Brownian motion. We obtain the signal to noise ratios for two methods of measurement. The intensity-field correlation function signal to noise ratio scales with the first power of vertical bar g((1))(tau). This is in contrast with the well-established result of g((2))(t)((2))(tau) which goes as the square of vertical bar g((1))(tau)vertical bar.}, keywords = {astrophysics, field correlation, intensity correlation, intensity-field correlation, Statistical Physics}, issn = {0031-8949}, doi = {10.1088/1402-4896/abac37}, author = {Siciak, A. and Hugbart, M. and Guerin, W. and Kaiser, R. and Orozco, L. A.} } @article {wu_competing_2020, title = {Competing quantum phases of hard-core bosons with tilted dipole-dipole interaction}, journal = {Phys. Rev. A}, volume = {102}, number = {5}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {nov}, abstract = {Different quantum phases of a hard-core boson induced by dipole-dipole interaction with varying angles of polarization are discussed in this work. We consider the two most influential leading terms with anisotropy due to the tilted polarization of the on-site boson in the square lattice. To ensure the concreteness of this truncation, we compare our phase diagrams, obtained numerically from the cluster mean-field theory (CMFT) and infinite projected entangled-pair state (iPEPS), with that of the long-range interacting model from quantum Monte Carlo. Next, we focus on the case where the azimuthal angle is fixed to phi = pi/4. Using the mean-field analysis where the quantum spin operators are replaced by c numbers, we aim to search for the underlying phases, especially the supersolid. Our results show a competing scenario mainly between two ordered phases with different sizes of unit cell, where a first-order transition takes place in between them. With the help of the CMFT and variational iPEPS, the phase boundaries predicted by the mean-field theory are determined more precisely. Our discoveries elucidate the possible underlying supersolid phases which might be seen in the ultracold experiments with strongly dipolar atoms. Moreover, our results indicate that an effective triangular optical lattice can be realized by fine tuning the polarization of dipoles in a square lattice.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.102.053306}, author = {Wu, Huan-Kuang and Tu, Wei-Lin} } @article { ISI:000530754200007, title = {Competition between factors determining bright versus dark atomic states within a laser mode}, journal = {Phys. Rev. A}, volume = {101}, number = {5}, year = {2020}, month = {MAY 7}, pages = {053410}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We observe bimodal fluorescence patterns from atoms in a fast atomic beam when the laser excitation occurs in the presence of a magnetic field and the atoms sample only a portion of the laser profile. The behavior is well explained by competition between the local intensity of the laser, which tends to generate a coherent-population-trapping (CPT) dark state in the J =1 to J{\textquoteright} = 0 system, and the strength of an applied magnetic field that can frustrate the CPT process. This work is relevant for understanding and optimizing the detection process for clocks or other coherent systems utilizing these transitions and could be applicable to in situ calibration of the laser-atom interaction, such as the strength of the magnetic field or laser intensity at a specific location.

}, issn = {2469-9926}, doi = {10.1103/PhysRevA.101.053410}, author = {Hemingway, Bryan and Akin, T. G. and Peil, Steven and Porto, J V} } @article { ISI:000581926500001, title = {Confinement of an alkaline-earth element in a grating magneto-optical trap}, journal = {Rev. Sci. Instrum.}, volume = {91}, number = {10}, year = {2020}, month = {OCT 1}, pages = {103202}, publisher = {AMER INST PHYSICS}, type = {Article}, abstract = {We demonstrate a compact magneto-optical trap (MOT) of alkaline-earth atoms using a nanofabricated diffraction grating chip. A single input laser beam, resonant with the broad S-1(0) -> P-1(1) transition of strontium, forms the MOT in combination with three diffracted beams from the grating chip and a magnetic field produced by permanent magnets. A differential pumping tube limits the effect of the heated, effusive source on the background pressure in the trapping region. The system has a total volume of around 2.4 l. With our setup, we have trapped up to 5 x 10(6) Sr-88 atoms at a temperature of similar to 6 mK, and with a trap lifetime of similar to 1 s. Our results will aid the effort to miniaturize quantum technologies based on alkaline-earth atoms.}, issn = {0034-6748}, doi = {10.1063/5.0019551}, author = {Sitaram, A. and Elgee, P. K. and Campbell, G. K. and Klimov, N. N. and Eckel, S. and Barker, D. S.} } @article { ISI:000506811300021, title = {Counting on Majorana modes}, journal = {Science}, volume = {367}, number = {6474}, year = {2020}, month = {JAN 10}, pages = {145}, publisher = {AMER ASSOC ADVANCEMENT SCIENCE}, type = {Article}, issn = {0036-8075}, doi = {10.1126/science.aaz9589}, author = {Sau, Jay} } @article { ISI:000532064500001, title = {Counting statistics of microwave photons in circuit QED}, journal = {Phys. Rev. A}, volume = {101}, number = {5}, year = {2020}, month = {MAY 13}, pages = {052321}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {In superconducting circuit architectures for quantum computing, microwave resonators are often used both to isolate qubits from the electromagnetic environment and to facilitate qubit state readout. We analyze the full counting statistics of photons emitted from such driven readout resonators both in and beyond the dispersive approximation. We calculate the overlap between emitted-photon distributions for the two qubit states and explore strategies for its minimization with the purpose of increasing fidelity of intensity-sensitive readout techniques. In the dispersive approximation and at negligible qubit relaxation, both distributions are Poissonian, and the overlap between them can be easily made arbitrarily small. Nondispersive terms of the Hamiltonian generate squeezing and the Purcell decay with the latter effect giving the dominant contribution to the overlap between two distributions.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.101.052321}, author = {Nesterov, Konstantin N. and Pechenezhskiy, V, Ivan and Vavilov, Maxim G.} } @article { ISI:000534162700004, title = {Creating solitons with controllable and near-zero velocity in Bose-Einstein condensates}, journal = {Phys. Rev. A}, volume = {101}, number = {5}, year = {2020}, month = {MAY 20}, pages = {053629}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Established techniques for deterministically creating dark solitons in repulsively interacting atomic Bose-Einstein condensates (BECs) can only access a narrow range of soliton velocities. Because velocity affects the stability of individual solitons and the properties of soliton-soliton interactions, this technical limitation has hindered experimental progress. Here we create dark solitons in highly anisotropic cigar-shaped BECs with arbitrary position and velocity by simultaneously engineering the amplitude and phase of the condensate wave function, improving upon previous techniques which explicitly manipulated only the condensate phase. The single dark soliton solution present in true one-dimensional (1D) systems corresponds to the kink soliton in anisotropic three-dimensional systems and is joined by a host of additional dark solitons, including vortex ring and solitonic vortex solutions. We readily create dark solitons with speeds from zero to half the sound speed. The observed soliton oscillation frequency suggests that we imprinted solitonic vortices, which for our cigar-shaped system are the only stable solitons expected for these velocities. Our numerical simulations of 1D BECs show this technique to be equally effective for creating kink solitons when they are stable. We demonstrate the utility of this technique by deterministically colliding dark solitons with domain walls in two-component spinor BECs.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.101.053629}, author = {Fritsch, A. R. and Lu, Mingwu and Reid, G. H. and Pineiro, A. M. and Spielman, I. B.} } @article { ISI:000510386300003, title = {Critical local moment fluctuations and enhanced pairing correlations in a cluster Anderson model}, journal = {Phys. Rev. B}, volume = {101}, number = {1}, year = {2020}, month = {JAN 31}, pages = {014452}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The appearance of unconventional superconductivity near heavy-fermion quantum critical points (QCPs) motivates investigation of pairing correlations close to a {\textquoteleft}{\textquoteleft}beyond Landau{{\textquoteright}{\textquoteright}} Kondo-destruction QCP. We focus on a two-Anderson-impurity cluster in which Kondo destruction is induced by a pseudogap in the conduction-electron density of states. Analysis via continuous-time quantum Monte Carlo and the numerical renormalization group reveals a previously unstudied QCP that both displays the critical-local moment fluctuations characteristic of Kondo destruction and leads to a strongly enhanced singlet-pairing susceptibility. Our results provide insights into the mechanism for superconductivity in quantum critical metals.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.014452}, author = {Cai, Ang and Pixley, J. H. and Ingersent, Kevin and Si, Qimiao} } @article {liang_cryspnet_2020, title = {{CRYSPNet}: {Crystal} structure predictions via neural networks}, journal = {Phys. Rev. Mater.}, volume = {4}, number = {12}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {dec}, abstract = {Structure is the most basic and important property of crystalline solids; it determines directly or indirectly most materials characteristics. However, predicting crystal structure of solids remains a formidable and not fully solved problem. Standard theoretical tools for this task are computationally expensive and at times inaccurate. Here we present an alternative approach utilizing machine learning for crystal structure prediction. We developed a tool called Crystal Structure Prediction Network (CRYSPNet) that can predict the Bravais lattice, space group, and lattice parameters of an inorganic material based only on its chemical composition. CRYSPNet consists of a series of neural network models, using as inputs predictors aggregating the properties of the elements constituting the compound. It was trained and validated on more than 100 000 entries from the Inorganic Crystal Structure Database. The tool demonstrates robust predictive capability and outperforms alternative strategies by a large margin. It can be used both as an independent prediction engine and as a method to generate candidate structures for further computational and/or experimental validation.

}, issn = {2475-9953}, doi = {10.1103/PhysRevMaterials.4.123802}, author = {Liang, Haotong and Stanev, Valentin and Kusne, A. Gilad and Takeuchi, Ichiro} } @article {colussi_cumulant_2020, title = {Cumulant theory of the unitary {Bose} gas: {Prethermal} and {Efimovian} dynamics}, journal = {Phys. Rev. A}, volume = {102}, number = {6}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {dec}, abstract = {We study the quench of a degenerate ultracold Bose gas to the unitary regime, where interactions are as strong as allowed by quantum mechanics. We lay the foundation of a cumulant theory able to simultaneously capture the three-body Efimov effect and ergodic evolution. After an initial period of rapid quantum depletion, a universal prethermal stage is established, characterized by a kinetic temperature and an emergent Bogoliubov dispersion law, while the microscopic degrees of freedom remain far from equilibrium. Integrability is then broken by higher-order interaction terms in the many-body Hamiltonian, leading to a momentum-dependent departure from power law to decaying exponential behavior of the occupation numbers at large momentum. We also find signatures of the Efimov effect in the many-body dynamics and make a precise identification between the observed beating phenomenon and the binding energy of an Efimov trimer. Throughout the paper, our predictions for a uniform gas are quantitatively compared with experimental results for quenched unitary Bose gases in uniform potentials.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.102.063314}, author = {Colussi, V. E. and Kurkjian, H. and Van Regemortel, M. and Musolino, S. and van de Kraats, J. and Wouters, M. and Kokkelmans, S. J. J. M. F.} } @article {tran_destructive_2020, title = {Destructive {Error} {Interference} in {Product}-{Formula} {Lattice} {Simulation}, journal = {Phys. Rev. Lett.}, volume = {124}, number = {22}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jun}, abstract = {Quantum computers can efficiently simulate the dynamics of quantum systems. In this Letter, we study the cost of digitally simulating the dynamics of several physically relevant systems using the first-order product-formula algorithm. We show that the errors from different Trotterization steps in the algorithm can interfere destructively, yielding a much smaller error than previously estimated. In particular, we prove that the total error in simulating a nearest-neighbor interacting system of n sites for time t using the first-order product formula with r time slices is O(nt/r + nt(3)/r(2)) when nt(2)/r is less than a small constant. Given an error tolerance epsilon, the error bound yields an estimate of max\{O(n(2)t/epsilon), O(n(2)t(3/2)/epsilon(1/2))\} for the total gate count of the simulation. The estimate is tighter than previous bounds and matches the empirical performance observed in Childs et al. [Proc. Natl. Acad. Sci. U.S.A. 115, 9456 (2018)]. We also provide numerical evidence for potential improvements and conjecture an even tighter estimate for the gate count.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.124.220502}, author = {Tran, Minh C. and Chu, Su-Kuan and Su, Yuan and Childs, Andrew M. and Gorshkov, V, Alexey} } @article { ISI:000569266900003, title = {Detecting Acoustic Blackbody Radiation with an Optomechanical Antenna}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {12}, year = {2020}, month = {SEP 15}, pages = {120603}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Nanomechanical systems are generally embedded in a macroscopic environment where the sources of thermal noise are difficult to pinpoint. We engineer a silicon nitride membrane optomechanical resonator such that its thermal noise is acoustically driven by a spatially well-defined remote macroscopic bath. This bath acts as an acoustic blackbody emitting and absorbing acoustic radiation through the silicon substrate. Our optomechanical system acts as a sensitive detector for the blackbody temperature and for photoacoustic imaging. We demonstrate that the nanomechanical mode temperature is governed by the blackbody temperature and not by the local material temperature of the resonator. Our work presents a route to mitigate self-heating effects in optomechanical thermometry and other quantum optomechanics experiments, as well as acoustic communication in quantum information.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.120603}, author = {Singh, Robinjeet and Purdy, Thomas P.} } @article { ISI:000557736300003, title = {Detection of the Lowest-Lying Odd-Parity Atomic Levels in Actinium}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {7}, year = {2020}, month = {AUG 10}, pages = {073001}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Two lowest-energy odd-parity atomic levels of actinium, 7s(2)7p(2)P(1/2)(0), 7s(2)7p(2)P(3/)(2)(0), were observed via two-step resonant laser-ionization spectroscopy and their respective energies were measured to be 7477.36(4) and 12 276.59(2) cm(-1). The lifetimes of these states were determined as 668(11) and 255(7) ns, respectively. In addition, we observed the effect of the hyperfine structure on the line for the transition to P-2(3)/2(0). These properties were calculated using a hybrid approach that combines configuration interaction and coupled-cluster methods, in good agreement with the experiment. The data are of relevance for understanding the complex atomic spectra of actinides and for developing efficient laser cooling and ionization schemes for actinium, with possible applications for high-purity medical-isotope production and future fundamental physics experiments.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.073001}, author = {Zhang, Ke and Studer, Dominik and Weber, Felix and Gadelshin, Vadim M. and Kneip, Nina and Raeder, Sebastian and Budker, Dmitry and Wendt, Klaus and Kieck, Tom and Porsev, Sergey G. and Cheung, Charles and Safronova, Marianna S. and Kozlov, Mikhail G.} } @article { ISI:000541833200001, title = {Development of gateless quantum Hall checkerboardp-njunction devices}, journal = {J. Phys. D-Appl. Phys.}, volume = {53}, number = {34}, year = {2020}, month = {AUG 19}, pages = {345302}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {Measurements of fractional multiples of the nu=2 plateau quantized Hall resistance (R-H approximate to 12 906 omega) were enabled by the utilization of multiple current terminals on millimetre-scale graphenep-njunction (pnJ) devices fabricated with interfaces along both lateral directions. These quantum Hall resistance checkerboard devices have been demonstrated to match quantized resistance outputs numerically calculated with the LTspice circuit simulator. From the devices{\textquoteright} functionality, more complex embodiments of the quantum Hall resistance checkerboard were simulated to highlight the parameter space within which these devices could operate. Moreover, these measurements suggest that the scalability ofpnJ fabrication on millimetre or centimetre scales is feasible with regards to graphene device manufacturing by using the far more efficient process of standard ultraviolet lithography.}, keywords = {epitaxial graphene, LTspice circuit simulator, p-njunctions, quantum Hall effect}, issn = {0022-3727}, doi = {10.1088/1361-6463/ab8d6f}, author = {Patel, Dinesh K. and Marzano, Martina and Liu, I, Chieh- and Kruskopf, Mattias and Elmquist, Randolph E. and Liang, Chi-Te and Rigosi, Albert F.} } @inbook {else_discrete_2020, title = {Discrete {Time} {Crystals}}, booktitle = {Annual Review of Condensed Matter Physics}, series = {Annual {Review} of {Condensed} {Matter} {Physics}}, volume = {11}, year = {2020}, note = {ISSN: 1947-5454 Journal Abbreviation: Annu. Rev. Condens. Matter Phys. Type: Review; Book Chapter}, pages = {467{\textendash}499}, publisher = {ANNUAL REVIEWS}, organization = {ANNUAL REVIEWS}, abstract = {Experimental advances have allowed for the exploration of nearly isolated quantum many-body systems whose coupling to an external bath is very weak. A particularly interesting class of such systems is those that do not thermalize under their own isolated quantum dynamics. In this review, we highlight the possibility for such systems to exhibit new nonequilibrium phases of matter. In particular, we focus on discrete time crystals, which are many-body phases of matter characterized by a spontaneously broken discrete time-translation symmetry. We give a definition of discrete time crystals from several points of view, emphasizing that they are a nonequilibrium phenomenon that is stabilized by many-body interactions, with no analog in noninteracting systems. We explain the theory behind several proposed models of discrete time crystals, and compare several recent realizations, in different experimental contexts.

}, keywords = {Floquet systems, isolated quantum many-body systems, many-body localization, spontaneous symmetry breaking, time-translation symmetry}, doi = {10.1146/annurev-conmatphys-031119-050658}, author = {Else, Dominic V. and Monroe, Christopher and Nayak, Chetan and Yao, Norman Y.}, editor = {Marchetti, MC and Mackenzie, AP} } @article {wilson_disorder_2020, title = {Disorder in twisted bilayer graphene}, journal = {Phys. Rev. Res.}, volume = {2}, number = {2}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jun}, abstract = {We develop a theory for a type of disorder in condensed matter systems arising from local twist-angle fluctuations in two strongly coupled van der Waals monolayers twisted with respect to each other to create a flat-band moire superlattice. The paradigm of {\textquotedblleft}twist-angle disorder{\textquotedblright} arises from the currently ongoing intense research activity in the physics of twisted bilayer graphene. In experimental samples of pristine twisted bilayer graphene, which are nominally free of impurities and defects, the main source of disorder is believed to arise from the unavoidable and uncontrollable nonuniformity of the twist angle across the sample. To address this physics of twist-angle disorder, we develop a real-space, microscopic model of twisted bilayer graphene where the angle enters as a free parameter. In particular, we focus on the size of single-particle energy gaps separating the miniband from the rest of the spectrum, the Van Hove peaks, the renormalized Dirac cone velocity near charge neutrality, and the minibandwidth. We find that the energy gaps and minibandwidth are strongly affected by disorder while the renormalized velocity remains virtually unchanged. We discuss the implications of our results for the ongoing experiments on twisted bilayer graphene. Our theory is readily generalized to future studies of twist-angle disorder effects on all electronic properties of moire superlattices created by twisting two coupled van der Waals materials with respect to each other.}, doi = {10.1103/PhysRevResearch.2.023325}, author = {Wilson, Justin H. and Fu, Yixing and Das Sarma, S. and Pixley, J. H.} } @article { ISI:000541476900001, title = {Dissipative Kerr Solitons in a III-V Microresonator}, journal = {Laser Photon. Rev.}, volume = {14}, number = {8}, year = {2020}, month = {AUG}, pages = {2000022}, publisher = {WILEY-V C H VERLAG GMBH}, type = {Article}, abstract = {Stable microresonator Kerr soliton frequency combs in a III-V platform (AlGaAs on SiO2) are demonstrated through quenching of thermorefractive effects by cryogenic cooling to temperatures between 4 and 20 K. This cooling reduces the resonator{\textquoteright}s thermorefractive coefficient, whose room-temperature value is an order of magnitude larger than that of other microcomb platforms like Si3N4, SiO2, and AlN, by more than two orders of magnitude, and makes soliton states adiabatically accessible. Realizing such phase-stable soliton operation is critical for applications that fully exploit the ultra-high effective nonlinearity and high optical quality factors exhibited by this platform.}, keywords = {frequency combs, GaAs, microcombs, nanophotonics, Nonlinear optics, soliton}, issn = {1863-8880}, doi = {10.1002/lpor.202000022},}, author = {Moille, Gregory and Chang, Lin and Xie, Weiqiang and Rao, Ashutosh and Lu, Xiyuan and Davanco, Marcelo and Bowers, John E. and Srinivasan, Kartik} } @article { ISI:000530026700003, title = {Drag viscosity of metals and its connection to Coulomb drag}, journal = {Phys. Rev. B}, volume = {101}, number = {19}, year = {2020}, month = {MAY 4}, pages = {195106}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Recent years have seen a surge of interest in studies of hydrodynamic transport in electronic systems. We investigate the electron viscosity of metals and find a component that is closely related to Coulomb drag. By using linear-response theory, viscosity, which is a transport coefficient for momentum, can be extracted from the retarded correlation function of the momentum flux, i.e., the stress tensor. There exists a previously overlooked contribution to the shear viscosity from the interacting part of the stress tensor which accounts for the momentum flow induced by interactions. This contribution, which we dub drag viscosity, is caused by the frictional drag force due to long-range interactions. It is therefore linked to Coulomb drag which also originates from the interaction-induced drag force. Starting from the Kubo formula and using the Keldysh technique, we compute the drag viscosity of two- and three-dimensional metals along with the drag resistivity of double-layer two-dimensional electronic systems. Both the drag resistivity and drag viscosity exhibit a crossover from quadraticin-T behavior at low temperatures to a linear behavior at higher temperatures. Although the drag viscosity appears relatively small compared with the normal Drude component for the clean metals, it may dominate hydrodynamic transport in some systems, which are discussed in the conclusion.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.195106}, author = {Liao, Yunxiang and Galitski, Victor} } @article { ISI:000530023600007, title = {d-wave superconductivity and Bogoliubov-Fermi surfaces in Rarita-Schwinger-Weyl semimetals}, journal = {Phys. Rev. B}, volume = {101}, number = {18}, year = {2020}, month = {MAY 4}, pages = {184503}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We uncover the properties of complex tensor (d-wave) superconducting order in three-dimensional Rarita-Schwinger-Weyl semimetals that host pseudospin-3/2 fermions at a fourfold linear band-crossing point. Although the general theory of d-wave order was originally developed for materials displaying quadratic band touching, it directly applies to the case of semimetals with linear dispersion, several candidate compounds of which have been discovered experimentally very recently. The spin-3/2 nature of the fermions allows for the formation of spin-2 Cooper pairs which may be described by a complex second-rank tensor order parameter. In the case of linear dispersion, for the chemical potential at the Fermi point and at strong coupling, the energetically preferred superconducting state is the uniaxial nematic state, which preserves time-reversal symmetry and provides a full (anisotropic) gap for quasiparticle excitations. In contrast, at a finite chemical potential, we find that the usual weak-coupling instability is toward the {\textquoteleft}{\textquoteleft}cyclic state,{{\textquoteright}{\textquoteright}} well known from the studies of multicomponent Bose-Einstein condensates, which breaks time-reversal symmetry maximally, has vanishing average value of angular momentum, and features 16 small Bogoliubov-Fermi surfaces. The Rarita-Schwinger-Weyl semimetals provide therefore the first example of weakly coupled, three-dimensional, isotropic d-wave superconductors where the d-wave superconducting phase is uniquely selected by the quartic expansion of the mean-field free energy, and is not afflicted by the accidental degeneracy first noticed by Mermin over 40 years ago. We discuss the appearance and stability of the Bogoliubov-Fermi surfaces in absence of inversion symmetry in the electronic Hamiltonian, as in the case at hand.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.184503}, author = {Link, Julia M. and Boettcher, Igor and Herbut, Igor F.} } @article {tran_dynamical_2020, title = {Dynamical {Josephson} effects in {NbSe2}, journal = {Phys. Rev. Res.}, volume = {2}, number = {4}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {nov}, abstract = {The study of superconducting materials that also possess nontrivial correlations or interactions remains an active frontier of condensed matter physics. NbSe2 belongs to this class of superconductors and recent research has focused on the two-dimensional properties of this layered, superconducting material. Often, electronic transport measurements are used to investigate the superconducting properties of these materials, hence it is key to obtain a thorough understanding of transport in these systems. We investigate the transition between the superconducting and resistive state using radio-frequency AC excitation. Despite being a single piece of superconductor, the devices show novel dynamical Josephson effects behavior reminiscent of the AC Josephson effect observed in Josephson junctions. Detailed analysis uncovers the origin of this effect, identifying two types of vortex motion that categorize the transition to the normal state. Our results shed light on the nature of superconductivity in this material, unearthing exotic phenomena by exploiting nonequilibrium superconducting effects in atomically thin materials.}, doi = {10.1103/PhysRevResearch.2.043204}, author = {Tran, S. and Sell, J. and Williams, J. R.} } @article { ISI:000544526900013, title = {Early-Time Exponential Instabilities in Nonchaotic Quantum Systems}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {1}, year = {2020}, month = {JUL 1}, pages = {014101}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The majority of classical dynamical systems are chaotic and exhibit the butterfly effect: a minute change in initial conditions has exponentially large effects later on. But this phenomenon is difficult to reconcile with quantum mechanics. One of the main goals in the field of quantum chaos is to establish a correspondence between the dynamics of classical chaotic systems and their quantum counterparts. In isolated systems in the absence of decoherence, there is such a correspondence in dynamics, but it usually persists only over a short time window, after which quantum interference washes out classical chaos. We demonstrate that quantum mechanics can also play the opposite role and generate exponential instabilities in classically nonchaotic systems within this early-time window. Our calculations employ the out-of-time-ordered correlator (OTOC)-a diagnostic that reduces to the Lyapunov exponent in the classical limit but is well defined for general quantum systems. We show that certain classically nonchaotic models, such as polygonal billiards, demonstrate a Lyapunov-like exponential growth of the OTOC at early times with Planck{\textquoteright}s-constant-dependent rates. This behavior is sharply contrasted with the slow early-time growth of the analog of the OTOC in the systems{\textquoteright} classical counterparts. These results suggest that classical-to-quantum correspondence in dynamics is violated in the OTOC even before quantum interference develops.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.014101}, author = {Rozenbaume, Efim B. and Bunimovich, Leonid A. and Galitski, Victor} } @article { ISI:000509352500053, title = {Effect of imperfect homodyne visibility on multi-spatial-mode two-mode squeezing measurements}, journal = {Opt. Express}, volume = {28}, number = {1}, year = {2020}, month = {JAN 6}, pages = {652-664}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {We study the effect of homodyne detector visibility on the measurement of quadrature squeezing for a spatially multi-mode source of two-mode squeezed light. Sources like optical parametric oscillators (OPO) typically produce squeezing in a single spatial mode because the nonlinear medium is within a mode-selective optical cavity. For such a source, imperfect interference visibility in the homodyne detector couples in additional vacuum noise, which can be accounted for by introducing an equivalent loss term. In a free-space multi-spatial-mode system imperfect homodyne detector visibility can couple in uncorrelated squeezed modes, and hence can cause faster degradation of the measured squeezing. We show experimentally the dependence of the measured squeezing level on the visibility of homodyne detectors used to probe two-mode squeezed states produced by a free space tour-wave mixing process in Rb-85 vapor, and also demonstrate that a simple theoretical model agrees closely with the experimental data. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {1094-4087}, doi = {10.1364/OE.379033}, author = {Gupta, Prasoon and Speirs, Rory W. and Jones, Kevin M. and Lett, Paul D.} } @article { ISI:000552791500001, title = {The effect of strain on tunnel barrier height in silicon quantum devices}, journal = {J. Appl. Phys.}, volume = {128}, number = {2}, year = {2020}, month = {JUL 14}, pages = {024303}, publisher = {AMER INST PHYSICS}, type = {Article}, abstract = {Semiconductor quantum dot (QD) devices experience a modulation of the band structure at the edge of lithographically defined gates due to mechanical strain. This modulation can play a prominent role in the device behavior at low temperatures, where QD devices operate. Here, we develop an electrical measurement of strain based on I ( V ) characteristics of tunnel junctions defined by aluminum and titanium gates. We measure relative differences in the tunnel barrier height due to strain consistent with experimentally measured coefficients of thermal expansion ( alpha) that differ from the bulk values. Our results show that the bulk parameters commonly used for simulating strain in QD devices incorrectly capture the impact of strain. The method presented here provides a path forward toward exploring different gate materials and fabrication processes in silicon QDs in order to optimize strain.}, issn = {0021-8979}, doi = {10.1063/5.0010253}, author = {Stein, Ryan M. and Stewart, Jr., M. D.} } @article {bringewatt_effective_2020, title = {Effective {Gaps} {Are} {Not} {Effective}: {Quasipolynomial} {Classical} {Simulation} of {Obstructed} {Stoquastic} {Hamiltonians}}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {17}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {oct}, abstract = {All known examples suggesting an exponential separation between classical simulation algorithms and stoquastic adiabatic quantum computing (StoqAQC) exploit symmetries that constrain adiabatic dynamics to effective, symmetric subspaces. The symmetries produce large effective eigenvalue gaps, which in turn make adiabatic computation efficient. We present a classical algorithm to subexponentially sample from an effective subspace of any k-local stoquastic Hamiltonian H, without a priori knowledge of its symmetries (or near symmetries). Our algorithm maps any k-local Hamiltonian to a graph G = (V, E) with vertical bar V vertical bar = O(poly(n)), where n is the number of qubits. Given the well-known result of Babai [Graph isomorphism in quasipolynomial time, in Proceedings of the Forty-Eighth Annual ACM Symposium on Theory of Computing (2016), pp. 684-697], we exploit graph isomorphism to study the automorphisms of G and arrive at an algorithm quasipolynomial in vertical bar V vertical bar for producing samples from effective subspace eigenstates of H. Our results rule out exponential separations between StoqAQC and classical computation that arise from hidden symmetries in k-local Hamiltonians. Our graph representation of H is not limited to stoquastic Hamiltonians and may rule out corresponding obstructions in nonstoquastic cases, or be useful in studying additional properties of k-local Hamiltonians.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.170504}, author = {Bringewatt, Jacob and Jarret, Michael} } @article { ISI:000568842200012, title = {Effects of conical intersections on hyperfine quenching of hydroxyl OH in collision with an ultracold Sr atom}, journal = {Sci Rep}, volume = {10}, number = {1}, year = {2020}, month = {AUG 24}, pages = {14130}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {The effect of conical intersections (CIs) on electronic relaxation, transitions from excited states to ground states, is well studied, but their influence on hyperfine quenching in a reactant molecule is not known. Here, we report on ultracold collision dynamics of the hydroxyl free-radical OH with Sr atoms leading to quenching of OH hyperfine states. Our quantum-mechanical calculations of this process reveal that quenching is efficient due to anomalous molecular dynamics in the vicinity of the conical intersection at collinear geometry. We observe wide scattering resonance features in both elastic and inelastic rate coefficients at collision energies below k(B) x 10mK. They are identified as either p- or d-wave shape resonances. We also describe the electronic potentials relevant for these non-reactive collisions, their diabatization procedure, as well as the non-adiabatic coupling between the diabatic potentials near the CIs.}, issn = {2045-2322}, doi = {10.1038/s41598-020-71068-w}, author = {Li, Ming and Klos, Jacek and Petrov, Alexander and Li, Hui and Kotochigova, Svetlana} } @article { ISI:000553250400007, title = {Efficient Ground-State Cooling of Large Trapped-Ion Chains with an Electromagnetically-Induced-Transparency Tripod Scheme}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {5}, year = {2020}, month = {JUL 29}, pages = {053001}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We report the electromagnetically-induced-transparency (EIT) cooling of a large trapped Yb-171(+) ion chain to the quantum ground state. Unlike conventional EIT cooling, we engage a four-level tripod structure and achieve fast sub-Doppler cooling over all motional modes. We observe simultaneous groundstate cooling across the complete transverse mode spectrum of up to 40 ions, occupying a bandwidth of over 3 MHz. The cooling time is observed to be less than 300 mu s, independent of the number of ions. Such efficient cooling across the entire spectrum is essential for high-fidelity quantum operations using trapped ion crystals for quantum simulators or quantum computers.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.053001}, author = {Feng, L. and Tan, W. L. and De, A. and Menon, A. and Chu, A. and Pagano, G. and Monroe, C.} } @article {19016, title = {Efficient photoinduced second-harmonic generation in silicon nitride photonics}, journal = {Nature Photonics}, year = {2020}, month = {11/2020}, abstract = {Silicon photonics lacks a second-order nonlinear optical (Ï‡(2)) response in general, because the typical constituent materials are centrosymmetric and lack inversion symmetry, which prohibits Ï‡(2) nonlinear processes such as second-harmonic generation (SHG). Here, we realize high SHG efficiency in silicon photonics by combining a photoinduced effective Ï‡(2) nonlinearity with resonant enhancement and perfect phase matching. We show a conversion efficiency of (2,500\ {\textpm}\ 100)\%\ W-1 that is two to four orders of magnitude larger than previous field-induced SHG works. In particular, our devices realize milliwatt-level SHG output powers with up to (22\ {\textpm}\ 1)\% power conversion efficiency. This demonstration is a breakthrough in realizing efficient Ï‡(2) processes in silicon photonics, and paves the way for further integration of self-referenced frequency combs and optical frequency references.

}, issn = {1749-4893}, doi = {10.1038/s41566-020-00708-4}, url = {https://doi.org/10.1038/s41566-020-00708-4}, author = {Lu, Xiyuan and Moille, Gregory and Rao, Ashutosh and Westly, Daron A. and Srinivasan, Kartik} } @conference {lu_efficient_2020, title = {Efficient second harmonic generation in a {Si3N4} microring}, booktitle = {Conference on Lasers and Electro-Optics (CLEO)}, series = {Conference on {Lasers} and {Electro}-{Optics}}, year = {2020}, note = {Backup Publisher: IEEE ISSN: 2160-9020 Type: Proceedings Paper}, publisher = {IEEE}, organization = {IEEE}, abstract = {We demonstrate efficient second harmonic generation in a silicon nitride microring, through perfect phase matching of a photogalvanic DC-field-induced chi((2)) process. The efficiency of 2,500 \%/W is {\textgreater} 100 x larger than the previous record in silicon photonics. (c) 2020 The Author(s)

}, isbn = {978-1-943580-76-7}, author = {Lu, Xiyuan and Moille, Gregory and Rao, Ashutosh and Westly, Daron and Li, Qing and Srinivasan, Kartik} } @conference {lu_efficient_2020-1, title = {Efficient widely-separated optical parametric oscillation}, booktitle = {Conference on Lasers and Electro-Optics (CLEO)}, series = {Conference on {Lasers} and {Electro}-{Optics}}, year = {2020}, note = {Backup Publisher: IEEE ISSN: 2160-9020 Type: Proceedings Paper}, publisher = {IEEE}, organization = {IEEE}, abstract = {We demonstrate the first widely-separated optical parametric oscillation in silicon nanophotonics, with milliwatt-level threshold power that is {\textgreater} 50 times smaller than other widely-separated OPOs. This demonstration is promising for on-chip visible light generation. (C) 2020 The Author(s)

}, isbn = {978-1-943580-76-7}, author = {Lu, Xiyuan and Moille, Gregory and Singh, Anshuman and Li, Qing and Westly, Daron and Rao, Ashutosh and Yu, Su-Peng and Briles, Travis C. and Drake, Tara and Papp, Scott B. and Srinivasan, Kartik} } @article { ISI:000510841200002, title = {Electron-induced massive dynamics of magnetic domain walls}, journal = {Phys. Rev. B}, volume = {101}, number = {5}, year = {2020}, month = {FEB 4}, pages = {054407}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study the dynamics of domain walls (DWs) in a metallic, ferromagnetic nanowire, focusing on inertial effects on the DW due to interaction with a conduction electron bath. We develop a Keldysh collective coordinate technique to describe the effect of conduction electrons on rigid magnetic structures. The effective Lagrangian and Langevin equations of motion for a DW are derived microscopically, including the full response kernel which is nonlocal in time. The DW dynamics is described by two collective degrees of freedom: position and tilt angle. The coupled Langevin equations therefore involve two correlated noise sources, leading to a generalized fluctuation-dissipation theorem (FDT). The DW response kernel due to electrons contains two parts: one related to dissipation via FDT and another reactive part. We prove that the latter term leads to a mass for both degrees of freedom, even though the intrinsic bare mass is zero. The electron-induced mass is present even in a clean system without pinning or specifically engineered potentials. The resulting equations of motion contain rich dynamical solutions and point toward a way to control domain wall motion in metals via the electronic system properties. We discuss two observable consequences of the mass, hysteresis in the DW dynamics, and resonant response to ac current.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.054407}, author = {Hurst, Hilary M. and Galitski, Victor and Heikkila, Tero T.} } @article {das_sarma_electron-phonon_2020, title = {Electron-phonon and electron-electron interaction effects in twisted bilayer graphene}, journal = {Ann. Phys.}, volume = {417}, year = {2020}, note = {Place: 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA Publisher: ACADEMIC PRESS INC ELSEVIER SCIENCE Type: Article}, month = {jun}, abstract = {By comparing with recently available experimental data from several groups, we critically discuss the manifestation of continuum many body interaction effects in twisted bilayer graphene (tBLG) with small twist angles and low carrier densities, which arise naturally within the Dirac cone approximation for the non-interacting band structure. We provide two specific examples of such continuum many body theories: one involving electron-phonon interaction and one involving electron-electron interaction. In both cases, the experimental findings are only partially quantitatively consistent with rather clear-cut leading-order theoretical predictions based on well-established continuum many body theories. We provide a critical discussion, based mainly on the currently available tBLG experimental data, on possible future directions for understanding many body renormalization involving electron-phonon and electron-electron interactions in the system. One definitive conclusion based on the comparison between theory and experiment is that the leading order 1-loop perturbative renormalization group theory completely fails to account for the electron-electron interaction effects in the strong-coupling limit of flatband moire tBLG system near the magic twist angle even at low doping where the Dirac cone approximation should apply. By contrast, approximate nonperturbative theoretical results based on Borel-Pade resummation or 1/N expansion seem to work well compared with experiments, indicating rather small interaction corrections to Fermi velocity or carrier effective mass. For electron-phonon interactions, however, the leading-order continuum theory works well except when van Hove singularities in the density of states come into play. (C) 2020 Elsevier Inc. All rights reserved.}, issn = {0003-4916}, doi = {10.1016/j.aop.2020.168193}, author = {Das Sarma, Sankar and Wu, Fengcheng} } @article {mueller_energy-based_2020, title = {Energy-{Based} {Plasmonicity} {Index} to {Characterize} {Optical} {Resonances} in {Nanostructures}}, journal = {J. Phys. Chem. C}, volume = {124}, number = {44, SI}, year = {2020}, note = {Place: 1155 16TH ST, NW, WASHINGTON, DC 20036 USA Publisher: AMER CHEMICAL SOC Type: Article}, month = {nov}, pages = {24331{\textendash}24343}, abstract = {Resonances sustained by plasmonic nanoparticles provide extreme electric field confinement and enhancement into the deep subwavelength domain for a plethora of applications. Recent progress in nanofabrication made it even possible to tailor the properties of nanoparticles consisting of only a few hundred atoms. These nanoparticles support both single-particle-like resonances and collective plasmonic charge density oscillations. Prototypical systems sustaining both features are graphene nanoantennas. In pushing the frontier of nanoscience, traditional identification, and classification of such resonances is at stake again. We show that in such nanostructures, the concerted electron cloud oscillation in real space does not necessarily come along with collective dynamics of conduction band electrons in energy space. This unveils an urgent need for a discussion of how a plasmon in nanostructures should be defined. Here, we propose to define it relying on energy space dynamics. The unambiguous identification of the plasmonic nature of a resonance is crucial to find out whether desirable plasmon-assisted features, such as frequency conversion processes, can be expected from a resonance. We elaborate an energy-based figure of merit that classifies the nature of resonances in nanostructures, motivated by tight binding simulations with a toy model consisting of a linear chain of atoms. We apply afterward the proposed figure of merit to a doped hexagonal graphene nanoantenna, which is known to support plasmons in the near infrared and single-particle-like transitions in the visible.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.0c07964}, author = {Mueller, Marvin M. and Kosik, Miriam and Pelc, Marta and Bryant, Garnett W. and Ayuela, Andres and Rockstuhl, Carsten and Slowik, Karolina} } @article { ISI:000562629600008, title = {Engineering quantum Hall phases in a synthetic bilayer graphene system}, journal = {Phys. Rev. B}, volume = {102}, number = {8}, year = {2020}, month = {AUG 26}, pages = {085430}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Synthetic quantum Hall bilayer (SQHB), realized by optically driven monolayer graphene in the quantum Hall regime, provides a flexible platform for engineering quantum Hall phases as discussed in Ghazaryan et al. {[}Phys. Rev. Lett. 119, 247403 (2017)]. The coherent driving which couples two Landau levels mimics an effective tunneling between synthetic layers. The tunneling strength, the effective Zeeman coupling, and two-body interaction matrix elements are tunable by varying the driving frequency and the driving strength. Using infinite density matrix renormalization group techniques combined with exact diagonalization, we show that the system exhibits a non-Abelian bilayer Fibonacci phase at filling fraction nu = 2/3. Moreover, at integer filling nu = 1, the SQHB exhibits quantum Hall ferromagnetism. Using Hartree-Fock theory and exact diagonalization, we show that excitations of the quantum Hall ferromagnet are topological textures known as skyrmions.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.085430}, author = {Cian, Ze-Pei and Grass, Tobias and Vaezi, Abolhassan and Liu, Zhao and Hafezi, Mohammad} } @article { ISI:000573650200006, title = {Enhanced transport of spin-orbit-coupled Bose gases in disordered potentials}, journal = {Phys. Rev. A}, volume = {102}, number = {3}, year = {2020}, month = {SEP 17}, pages = {033325}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Anderson localization is a single-particle localization phenomena in disordered media that is accompanied by an absence of diffusion. Spin-orbit coupling (SOC) describes an interaction between a particle{\textquoteright}s spin and its momentum that directly affects its energy dispersion, for example, creating dispersion relations with gaps and multiple local minima We show theoretically that combining one-dimensional spin-orbit coupling with a transverse Zeeman field suppresses the effects of disorder, thereby increasing the localization length and conductivity. This increase results from a suppression of backscattering between states in the gap of the SOC dispersion relation. Here, we focus specifically on the interplay of disorder from an optical speckle potential and SOC generated by two-photon Raman processes in quasi-one-dimensional Bose-Einstein condensates. We first describe backscattering by using a Fermi golden rule approach, and then numerically confirm this picture by solving the time-dependent one-dimensional Gross-Pitaevskii equation for a weakly interacting Bose-Einstein condensate with SOC and disorder. We find that on the tens of millisecond timescale of typical cold atom experiments moving in harmonic traps, initial states with momentum in the zero-momentum SOC gap evolve with negligible backscattering, while without SOC these same states rapidly localize.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.102.033325}, author = {Yue, Y. and de Melo, C. A. R. Sa and Spielman, I. B.} } @article {eldredge_entanglement_2020, title = {Entanglement bounds on the performance of quantum computing architectures}, journal = {Phys. Rev. Res.}, volume = {2}, number = {3}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {aug}, abstract = {There are many possible architectures of qubit connectivity that designers of future quantum computers will need to choose between. However, the process of evaluating a particular connectivity graph{\textquoteright}s performance as a quantum architecture can be difficult. In this paper, we show that a quantity known as the isoperimetric number establishes a lower bound on the time required to create highly entangled states. This metric we propose counts resources based on the use of two-qubit unitary operations, while allowing for arbitrarily fast measurements and classical feedback. We use this metric to evaluate the hierarchical architecture proposed by A. Bapat et al. [Phys. Rev. A 98, 062328 (2018)] and find it to be a promising alternative to the conventional grid architecture. We also show that the lower bound that this metric places on the creation time of highly entangled states can be saturated with a constructive protocol, up to a factor logarithmic in the number of qubits.}, doi = {10.1103/PhysRevResearch.2.033316}, author = {Eldredge, Zachary and Zhou, Leo and Bapat, Aniruddha and Garrison, James R. and Deshpande, Abhinav and Chong, Frederic T. and Gorshkov, V, Alexey} } @article { ISI:000515058400001, title = {Exact boundary modes in an interacting quantum wire}, journal = {Phys. Rev. B}, volume = {101}, number = {8}, year = {2020}, month = {FEB 21}, pages = {085133}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The boundary modes of one-dimensional quantum systems can play host to a variety of remarkable phenomena. They can be used to describe the physics of impurities in higher-dimensional systems, such as the ubiquitous Kondo effect, or can support Majorana bound states, which play a crucial role in the realm of quantum computation. In this work we examine the boundary modes in an interacting quantum wire with a proximity-induced pairing term. We solve the system exactly using the Bethe ansatz and show that for certain boundary conditions the spectrum contains bound states localized about either edge. The model is shown to exhibit a first-order phase transition as a function of the interaction strength such that for attractive interactions the ground state has bound states at both ends of the wire, while for repulsive interactions they are absent. In addition we see that the bound-state energy lies within the gap for all values of the interaction strength but undergoes a sharp avoided level crossing for sufficiently strong interaction, thereby preventing its decay. This avoided crossing is shown to occur as a consequence of an exact self-duality which is present in the model.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.085133}, author = {Rylands, Colin} } @article { ISI:000562633900003, title = {Exotic Photonic Molecules via Lennard-Jones-like Potentials}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {9}, year = {2020}, month = {AUG 26}, pages = {093601}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Ultracold systems offer an unprecedented level of control of interactions between atoms. An important challenge is to achieve a similar level of control of the interactions between photons. Towards this goal, we propose a realization of a novel Lennard-Jones-like potential between photons coupled to the Rydberg states via electromagnetically induced transparency (EIT). This potential is achieved by tuning Rydberg states to a Forster resonance with other Rydberg states. We consider few-body problems in 1D and 2D geometries and show the existence of self-bound clusters ({{\textquoteright}{\textquoteright}}molecules{{\textquoteright}{\textquoteright}}) of photons. We demonstrate that for a few-body problem, the multibody interactions have a significant impact on the geometry of the molecular ground state. This leads to phenomena without counterparts in conventional systems: For example, three photons in two dimensions preferentially arrange themselves in a line configuration rather than in an equilateral-triangle configuration. Our result opens a new avenue for studies of many-body phenomena with strongly interacting photons.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.093601}, author = {Bienias, Przemyslaw and Gullans, Michael J. and Kalinowski, Marcin and Craddock, Alexander N. and Ornelas-Huerta, Dalia P. and Rolston, S. L. and Porto, V, J. and Gorshkov, V, Alexey} } @article {jabir_experimental_2020, title = {Experimental demonstration of the near-quantum optimal receiver}, journal = {OSA Continuum}, volume = {3}, number = {12}, year = {2020}, note = {Place: 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA Publisher: OPTICAL SOC AMER Type: Article}, month = {dec}, pages = {3324+}, abstract = {We implement the cyclic quantum receiver based on the theoretical proposal of Roy Bondurant and demonstrate experimentally below the shot-noise limit (SNL) discrimination of quadrature phase-shift keying signals (PSK). We also experimentally test the receiver generalized for longer communication alphabet lengths and coherent frequency shift keying (CFSK) encoding. Using off-the-shelf components, we obtain state discrimination error rates that are 3 dB and 4.6 dB below the SNLs of ideal classical receivers for quadrature PSK and CFSK encodings, respectively. The receiver unconditionally surpasses the SNL for M=8 PSK and CFSK. This receiver can be used for the simple and robust practical implementation of quantum-enhanced optical communication. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {2578-7519}, doi = {10.1364/OSAC.409200}, author = {Jabir, V, M. and Burenkov, I. A. and Annafianto, N. Fajar R. and Battou, A. and Polyakov, V, S.} } @article {winer_exponential_2020, title = {Exponential {Ramp} in the {Quadratic} {Sachdev}-{Ye}-{Kitaev} {Model}}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {25}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {dec}, abstract = {A long period of linear growth in the spectral form factor provides a universal diagnostic of quantum chaos at intermediate times. By contrast, the behavior of the spectral form factor in disordered integrable many-body models is not well understood. Here we study the two-body Sachdev-Ye-Kitaev model and show that the spectral form factor features an exponential ramp, in sharp contrast to the linear ramp in chaotic models. We find a novel mechanism for this exponential ramp in terms of a high-dimensional manifold of saddle points in the path integral formulation of the spectral form factor. This manifold arises because the theory enjoys a large symmetry group. With finite nonintegrable interaction strength, these delicate symmetries reduce to a relative time translation, causing the exponential ramp to give way to a linear ramp.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.250602}, author = {Winer, Michael and Jian, Shao-Kai and Swingle, Brian} } @article {yang_extended_2020, title = {Extended nonergodic regime and spin subdiffusion in disordered {SU}(2)-symmetric {Floquet} systems}, journal = {Phys. Rev. B}, volume = {102}, number = {21}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {dec}, abstract = {We explore thermalization and quantum dynamics in a one-dimensional disordered SU(2)-symmetric Floquet model, where a many-body localized phase is prohibited by the non-Abelian symmetry. Despite the absence of localization, we find an extended nonergodic regime at strong disorder where the system exhibits nonthermal behaviors. In the strong disorder regime, the level spacing statistics exhibit neither a Wigner-Dyson nor a Poisson distribution, and the spectral form factor does not show a linear-in-time growth at early times characteristic of random matrix theory. The average entanglement entropy of the Floquet eigenstates is subthermal, although violating an area-law scaling with system sizes. We further compute the expectation value of local observables and find strong deviations from the eigenstate thermalization hypothesis. The infinite-temperature spin autocorrelation function decays at long times as t(-beta) with beta {\textless} 0.5, indicating subdiffusive transport at strong disorders.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.214205}, author = {Yang, Zhi-Cheng and Nicholls, Stuart and Cheng, Meng} } @article { ISI:000526522000042, title = {Extreme ultraviolet photon conversion efficiency of tetraphenyl butadiene}, journal = {Appl. Optics}, volume = {59}, number = {4}, year = {2020}, month = {FEB 1}, pages = {1217-1224}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {Extreme ultraviolet (EUV) radiation can be converted to visible light using tetraphenyl butadiene (TPB) as a phosphor. 1 mu m films of TPB were prepared using thermal vapor deposition of the pure material and by spin coating suspensions of TPB in high-molecular-weight polystyrene/toluene solutions. Calibrated sources and detectors were used to determine the effective photon conversion efficiency of the films for incident EUV radiation in the wavelength range of 125 nm <= lambda <= 200 nm. After exposure to atmosphere, the efficiency of the vapor-deposited films decreased significantly, while the efficiency of the spin-coated films remained unchanged. The production of TPB films by spin coating offers the advantages of simplicity and long-term stability. (C) 2020 Optical Society of America}, issn = {1559-128X}, doi = {10.1364/AO.380185}, author = {Graybill, Joshua R. and Shahi, Chandra B. and Coplan, Michael A. and Thompson, Alan K. and Vest, Robert E. and Clark, Charles W.} } @article {hurst_feedback_2020, title = {Feedback induced magnetic phases in binary {Bose}-{Einstein} condensates}, journal = {Phys. Rev. Res.}, volume = {2}, number = {4}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {dec}, abstract = {Weak measurement in tandem with real-time feedback control is a new route toward engineering novel nonequilibrium quantum matter. Here we develop a theoretical toolbox for quantum feedback control of multicomponent Bose-Einstein condensates (BECs) using backaction-limited weak measurements in conjunction with spatially resolved feedback. Feedback in the form of a single-particle potential can introduce effective interactions that enter into the stochastic equation governing system dynamics. The effective interactions are tunable and can be made analogous to Feshbach resonances-spin independent and spin dependent-but without changing atomic scattering parameters. Feedback cooling prevents runaway heating due to measurement backaction and we present an analytical model to explain its effectiveness. We showcase our toolbox by studying a two-component BEC using a stochastic mean-field theory, where feedback induces a phase transition between easy-axis ferromagnet and spin-disordered paramagnet phases. We present the steady-state phase diagram as a function of intrinsic and effective spin-dependent interaction strengths. Our result demonstrates that closed-loop quantum control of Bose-Einstein condensates is a powerful tool for quantum engineering in cold-atom systems.}, doi = {10.1103/PhysRevResearch.2.043325}, author = {Hurst, Hilary M. and Guo, Shangjie and Spielman, I. B.} } @article { ISI:000571392500002, title = {Fermion parity gap and exponential ground state degeneracy of the one-dimensional Fermi gas with intrinsic attractive interaction}, journal = {Phys. Rev. B}, volume = {102}, number = {12}, year = {2020}, month = {SEP 21}, pages = {125135}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We examine the properties of a one-dimensional (1D) Fermi gas with attractive intrinsic (Hubbard) interactions in the presence of spin-orbit coupling and Zeeman field by numerically computing the pair binding energy, excitation gap, and susceptibility to local perturbations using the density matrix renormalization group. Such a system can, in principle, be realized in a system of ultracold atoms confined in a 1D optical lattice. We note that, in the presence of spatial interfaces introduced by a smooth parabolic potential, the pair binding and excitation energy of the system decays exponentially with the system size, pointing to the existence of an exponential ground state degeneracy, and is consistent with recent works. However, the susceptibility of the ground state degeneracy of this number-conserving system to local impurities indicates that the energy gap vanishes as a power law with the system size in the presence of local perturbations. We compare this system with the more familiar system of an Ising antiferromagnet in the presence of a transverse field realized with Rydberg atoms and argue that the exponential splitting in the clean number-conserving 1D Fermi system is similar to a phase with only conventional order.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.125135}, author = {Roy, Monalisa Singh and Kumar, Manoranjan and Sau, Jay D. and Tewari, Sumanta} } @article { ISI:000579337200002, title = {Fermi-surface topology and renormalization of bare ellipticity in an interacting anisotropic electron gas}, journal = {Phys. Rev. B}, volume = {102}, number = {16}, year = {2020}, month = {OCT 19}, pages = {161114}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We investigate effects of electron-electron interactions on the shape of the Fermi surface in an anisotropic two-dimensional electron gas using the {\textquoteleft}{\textquoteleft}RPA-GW{{\textquoteright}{\textquoteright}} self-energy approximation. We find that the interacting Fermi surface deviates from an ellipse but not in an arbitrary way. The interacting Fermi surface has only two qualitatively distinct shapes for most values of r(s). The Fermi surface undergoes two distinct transitions between these two shapes as r(s) increases. For larger r(s), the degree of the deviation from an ellipse rapidly increases, but, in general, our theory provides a justification for the widely used elliptical Fermi-surface approximation, even for the interacting system, since the nonelliptic corrections are quantitatively rather small except for very large r(s).}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.161114}, author = {Ahn, Seongjin and Das Sarma, S.} } @article {alavirad_ferromagnetism_2020, title = {Ferromagnetism and its stability from the one-magnon spectrum in twisted bilayer graphene}, journal = {Phys. Rev. B}, volume = {102}, number = {23}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {dec}, abstract = {We study ferromagnetism and its stability in twisted bilayer graphene. We work with a Hubbard-like interaction that corresponds to the screened Coulomb interaction in a well-defined limit where the Thomas-Fermi screening length l(TF) is much larger than monolayer graphene{\textquoteright}s lattice spacing l(g) {\textless}{\textless} l(TF) and much smaller than the moire superlattice{\textquoteright}s spacing l(TF) {\textless}{\textless} l(moire). We show that in the perfectly flat band {\textquotedblleft}chiral{\textquotedblright} limit and at filling fractions +/- 3/4, the saturated ferromagnetic (spin- and valley-polarized) states are ideal ground-state candidates in the large band-gap limit. By assuming a large enough substrate (hBN) induced sublattice potential, the same argument can be applied to filling fractions +/- 1/4. We estimate the regime of stability of the ferromagnetic phase around the chiral limit by studying the exactly calculated spectrum of one-magnon excitations. The instability of the ferromagnetic state is signaled by a negative magnon excitation energy. This approach allows us to deform the results of the idealized chiral model (by increasing the bandwidth and/or modified interactions) toward more realistic systems. Furthermore, we use the low-energy part of the exact one-magnon spectrum to calculate the spin-stiffness of the Goldstone modes throughout the ferromagnetic phase. The calculated value of spin-stiffness can determine the excitation energy of charged skyrmions.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.235123}, author = {Alavirad, Yahya and Sau, Jay} } @article { ISI:000529804100001, title = {Ferromagnetism and superconductivity in twisted double bilayer graphene}, journal = {Phys. Rev. B}, volume = {101}, number = {15}, year = {2020}, month = {APR 30}, pages = {155149}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We present a theory of competing ferromagnetic and superconducting orders in twisted double bilayer graphene. In our theory, ferromagnetism is induced by Coulomb repulsion, while superconductivity with intervalley equal-spin pairing can be mediated by electron-acoustic phonon interactions. We calculate the transition temperatures for ferromagnetism and superconductivity as a function of moire band filling factor, and find that superconducting domes can appear on both the electron and hole sides of the ferromagnetic insulator at half filling. We show that the ferromagnetic insulating gap has a dome shape dependence on the layer potential difference, which provides an explanation to the experimental observation that the ferromagnetic insulator only develops over a finite range of external displacement field. We also verify the stability of the half filled ferromagnetic insulator against two types of collective excitations, i.e., spin magnons and valley magnons.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.155149}, author = {Wu, Fengcheng and Das Sarma, Sankar} } @article { ISI:000559739800002, title = {Feshbach Resonances in p-Wave Three-Body Recombination within Fermi-Fermi Mixtures of Open-Shell Li-6 and Closed-Shell Yb-173 Atoms}, journal = {Phys. Rev. X}, volume = {10}, number = {3}, year = {2020}, month = {AUG 14}, pages = {031037}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We report on the observation of magnetic Feshbach resonances in a Fermi-Fermi mixture of ultracold atoms with extreme mass imbalance and on their unique p-wave dominated three-body recombination processes. Our systemconsists of open-shell alkali-metal Li-6 and closed-shell Yb-173 atoms, both spin polarized and held at various temperatures between 1 and 20 mu K. We confirmthat Feshbach resonances in this systemare solely the result of a weak separation-dependent hyperfine coupling between the electronic spin of Li-6 and the nuclear spin of Yb-173. Our analysis also shows that three-body recombination rates are controlled by the identical fermion nature of the mixture, even in the presence of s-wave collisions between the two species and with recombination rate coefficients outside the Wigner threshold regime at our lowest temperature. Specifically, a comparison of experimental and theoretical line shapes of the recombination process indicates that the characteristic asymmetric line shape as a function of applied magnetic field and a maximum recombination rate coefficient that is independent of temperature can only be explained by triatomic collisions with nonzero, p-wave total orbital angular momentum. The resonances can be used to form ultracold doublet ground-state molecules and to simulate quantum superfluidity in mass-imbalanced mixtures.}, issn = {2160-3308}, doi = {10.1103/PhysRevX.10.031037}, author = {Green, Alaina and Li, Hui and Toh, Jun Hui See and Tang, Xinxin and McCormick, Katherine C. and Li, Ming and Tiesinga, Eite and Kotochigova, Svetlana and Gupta, Subhadeep} } @article { ISI:000552576600008, title = {Fidelity of a sequence of SWAP operations on a spin chain}, journal = {Phys. Rev. B}, volume = {102}, number = {3}, year = {2020}, month = {JUL 27}, pages = {035439}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We consider the {\textquoteleft}{\textquoteleft}transport{{\textquoteright}{\textquoteright}} of the state of a spin across a Heisenberg-coupled spin chain via the use of repeated SWAP gates, starting with one of two states-one in which the leftmost spin is down and the others up, and one in which the leftmost two spins are in a singlet state (i.e., they are entangled), and the others are again all up. More specifically, we transport the state of the leftmost spin in the first case and the next-to-leftmost spin in the second to the other end of the chain, and then back again. We accomplish our SWAP operations here by increasing the exchange coupling between the two spins that we operate on from a base value J to a larger value J(SWAP) for a time t = pi(h) over bar /4J(SWAP). We determine the fidelity of this sequence of operations in a number of situations-one in which only nearest-neighbor coupling exists between spins and there is no magnetic dipole-dipole coupling or noise (the most ideal case), one in which we introduce next-nearest-neighbor coupling, but none of the other effects, and one in which all of these effects are present. In the last case, the noise is assumed to be quasistatic, i.e., the exchange couplings are each drawn from a Gaussian distribution, truncated to only nonnegative values. We plot the fidelity as a function of JSWAP to illustrate various effects, namely crosstalk due to coupling to other spins, as well as noise, that are detrimental to our ability to perform a SWAP operation. Our theory should be useful to the ongoing experimental efforts in building semiconductor-based spin quantum computer architectures.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.035439}, author = {Throckmorton, Robert E. and Das Sarma, S.} } @article { ISI:000536153200001, title = {Figures of merit for quantum transducers}, journal = {Quantum Sci. Technol.}, volume = {5}, number = {3}, year = {2020}, month = {JUL}, pages = {034009}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {Recent technical advances have sparked renewed interest in physical systems that couple simultaneously to different parts of the electromagnetic spectrum, thus enabling transduction of signals between vastly different frequencies at the level of single quanta. Such hybrid systems have demonstrated frequency conversion of classical signals and have the potential of enabling quantum state transfer, e.g., between superconducting circuits and traveling optical signals. This article describes a simple approach for the theoretical characterization of the performance of quantum transducers. Given that, in practice, one cannot attain ideal one-to-one quantum conversion, we explore how imperfections impact the performance of the transducer in various scenarios. We quantify how knowledge of the well-established transducer parameters signal transfer efficiency eta and added noise N suffices to assess its performance in a variety of transduction schemes ranging from classical signal detection to applications for quantum information processing.}, keywords = {quantum sensing, quantum transduction, transduction}, issn = {2058-9565}, doi = {10.1088/2058-9565/ab8962}, author = {Zeuthen, Emil and Schliesser, Albert and Sorensen, Anders S. and Taylor, Jacob M.} } @article { ISI:000535764500002, title = {Filter-free single-photon quantum dot resonance fluorescence in an integrated cavity-waveguide device}, journal = {Optica}, volume = {7}, number = {5}, year = {2020}, month = {MAY 20}, pages = {380-385}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {Semiconductor quantum dots embedded in micropillar cavities are excellent emitters of single photons when pumped resonantly. Often, the same spatial mode is used to both resonantly excite a quantum-dot state and to collect the emitted single photons, requiring cross polarization to reduce the uncoupled scattered laser light. This inherently reduces the source brightness to 50\%. Critically, for some quantum applications the total efficiency from generation to detection must be over 50\%. Here, we demonstrate a resonant-excitation approach to creating single photons that is free of any cross polarization, and in fact any filtering whatsoever. It potentially increases single-photon rates and collection efficiencies, and simplifies operation. This integrated device allows us to resonantly excite single quantum-dot states in several cavities in the plane of the device using connected waveguides, while the cavity-enhanced single-photon fluorescence is directed vertically (off-chip) in a Gaussian mode. We expect this design to be a prototype for larger chip-scale quantum photonics. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {2334-2536}, doi = {10.1364/OPTICA.382273}, author = {Huber, Tobias and Davanco, Marcelo and Muller, Markus and Shuai, Yichen and Gazzano, Olivier and Solomon, Glenn S.} } @article { ISI:000562933100003, title = {Finite-temperature spectroscopy of dirty helical Luttinger liquids}, journal = {Phys. Rev. B}, volume = {102}, number = {8}, year = {2020}, month = {AUG 27}, pages = {085152}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We develop a theory of finite-temperature momentum-resolved tunneling spectroscopy (MRTS) for disordered, interacting, two-dimensional, topological-insulator edges. The MRTS complements conventional electrical transport measurement in characterizing the properties of the helical Luttinger liquid edges. Using the standard bosonization technique, we study low-energy spectral function and the MRTS tunneling current, providing a detailed description controlled by disorder, interaction, and temperature, taking into account Rashba spin-orbit coupling, interedge interaction, and distinct edge velocities. Our theory provides a systematic description of the spectroscopic signals in the MRTS measurement we hope will stimulate future experimental studies on the two-dimensional time-reversal invariant topological insulator.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.085152}, author = {Hsieh, Tzu-Chi and Chou, Yang-Zhi and Radzihovsky, Leo} } @article {hsiang_fluctuation-dissipation_2020, title = {Fluctuation-dissipation relation for open quantum systems in a nonequilibrium steady state}, journal = {Phys. Rev. D}, volume = {102}, number = {10}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {nov}, abstract = {Continuing our work on the nature and existence of fluctuation-dissipation relations (FDR) in linear and nonlinear open quantum systems [J.-T. Hsiang, B. L. Hu, and S.-Y. Lin, Phys. Rev. D 100, 025019 (2019); J.-T. Hsiang, B. L. Hu, S.-Y. Lin, and K. Yamamoto, Phys. Lett. B 795, 694 (2019); J.-T. Hsiang and B. L. Hu, Physics (Utrecht) 1, 430 (2019); J.-T. Hsiang and B. L. Hu, Phys. Rev. D 101, 125003 (2020)], here we consider such relations when a linear system is in a nonequilibrium steady state (NESS). With the model of two-oscillators (considered as a short harmonic chain with the two ends) each connected to a thermal bath of different temperatures we find that when the chain is fully relaxed due to interaction with the baths, the relation that connects the noise kernel and the imaginary part of the dissipation kernel of the chain in one bath does not assume the conventional form for the FDR in equilibrium cases. There exists an additional term we call the {\textquotedblleft}bias current{\textquotedblright} that depends on the difference of the bath{\textquoteright}s initial temperatures and the interoscillator coupling strength. We further show that this term is related to the steady heat flow between the two baths when the system is in an NESS. The ability to know the real-time development of the interheat exchange (between the baths and the end-oscillators) and the intraheat transfer (within the chain) and their dependence on the parameters in the system offers possibilities for quantifiable control, and in the design of quantum heat engines, or thermal devices.}, issn = {2470-0010}, doi = {10.1103/PhysRevD.102.105006}, author = {Hsiang, Jen-Tsung and Hu, Bei-Lok} } @article {hsiang_fluctuation-dissipation_2020-1, title = {Fluctuation-dissipation relation from the nonequilibrium dynamics of a nonlinear open quantum system}, journal = {Phys. Rev. D}, volume = {101}, number = {12}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jun}, abstract = {Continuing our inquiry into the conditions when fluctuation-dissipation relations (FDR) may appear in the context of nonequilibrium dynamics of open quantum systems (over and beyond the conventional FDR from linear response theory) we turn to non-Gaussian systems and consider this issue for an anharmonic quantum oscillator interacting with a scalar quantum field bath. We present the general nonperturbative expressions for the rate of energy (power) exchange between the anharmonic oscillator and its thermal bath. For the cases that a stable final equilibrium state exists, and the nonstationary components of the two-point functions of the anharmonic oscillator have negligible contributions to the power balance, we can show nonperturbatively that equilibration implies an FDR for the anharmonic oscillator. We then use a weakly anharmonic oscillator as an example to illustrate the validity of those two assumptions and show that in the weak anhamonicity limit, they are satisfied according to our first-order perturbative results..}, issn = {1550-7998}, doi = {10.1103/PhysRevD.101.125003}, author = {Hsiang, Jen-Tsung and Hu, Bei-Lok} } @article { ISI:000551007800002, title = {Fluctuations in Extractable Work Bound the Charging Power of Quantum Batteries}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {4}, year = {2020}, month = {JUL 22}, pages = {040601}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study the connection between the charging power of quantum batteries and the fluctuations of the extractable work. We prove that in order to have a nonzero rate of change of the extractable work, the state rho(W) of the battery cannot be an eigenstatc of a {\textquoteleft}{\textquoteleft}free energy operator,{{\textquoteright}{\textquoteright}} defined by F H-W + beta(-1) log(rho(W)), where H-W is the Hamiltonian of the battery and beta is the inverse temperature of a reference thermal bath with respect to which the extractable work is calculated. We do so by proving that fluctuations in the free energy operator upper bound the charging power of a quantum battery. Our findings also suggest that quantum coherence in the battery enhances the charging process, which we illustrate on a toy model of a heat engine.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.040601}, author = {Pedro Garcia-Pintos, Luis and Hamma, Alioscia and del Campo, Adolfo} } @article {sau_anyons_2020, title = {From anyons to {Majoranas}}, journal = {Nat. Rev. Phys.}, volume = {2}, number = {12}, year = {2020}, note = {Place: CAMPUS, 4 CRINAN ST, LONDON, N1 9XW, ENGLAND Publisher: SPRINGERNATURE Type: Editorial Material}, month = {dec}, pages = {667{\textendash}668}, abstract = {Key advances Beam-splitter and interferometric measurements in the quantum Hall regime provide the strongest experimental proof to date of exotic anyonic particles. Individual states inside superconducting vortices, called Caroli-de Gennes-Matricon states, have been experimentally observed in low-density topological superconductors. Access to the Caroli-de Gennes-Matricon states provides a new platform in which anyonic particles may be braided and detected in three dimensional topological superconductors. Anyons, particles that are neither bosons nor fermions, were predicted in the 1980s, but strong experimental evidence for the existence of the simplest type of anyons has only emerged this year. Further theoretical and experimental advances promise to nail the existence of more exotic types of anyons, such as Majorana fermions, which would make topological quantum computation possible. Strong experimental evidence for the existence of the simplest type of anyons (particles that are neither bosons nor fermions) has emerged this year. The next step is to uncover more exotic types of anyons, such as Majorana fermions.

}, doi = {10.1038/s42254-020-00251-9}, author = {Sau, Jay and Simon, Steven and Vishveshwara, Smitha and Williams, James R.} } @article { ISI:000562277400001, title = {Frustration-induced supersolid phases of extended Bose-Hubbard model in the hard-core limit}, journal = {J. Phys.-Condes. Matter}, volume = {32}, number = {45}, year = {2020}, month = {OCT 28}, pages = {455401}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {We investigate exotic supersolid phases in the extended Bose-Hubbard model with infinite projected entangled-pair state, numerical exact diagonalization, and mean-field theory. We demonstrate that many different supersolid phases can be generated by changing signs of hopping terms, and the interactions along with the frustration of hopping terms are important to stabilize those supersolid states. We argue the effect of frustration introduced by the competition of hopping terms in the supersolid phases from the mean-field point of view. This helps to give a clearer picture of the background mechanism for underlying superfluid/supersolid states to be formed. With this knowledge, we predict and realize thed-wave superfluid, which shares the same pairing symmetry with high-T(c)materials, and its extended phases. We believe that our results contribute to preliminary understanding for desired target phases in the real-world experimental systems.}, keywords = {Bose-Hubbard model, exact diagonalization, phase diagrams, projected entangled pair states, superfluids, supersolids}, issn = {0953-8984}, doi = {10.1088/1361-648X/aba383}, author = {Tu, Wei-Lin and Wu, Huan-Kuang and Suzuki, Takafumi} } @article {morita_full-dimensional_2020, title = {Full-dimensional quantum scattering calculations on ultracold atom-molecule collisions in magnetic fields: {The} role of molecular vibrations}, journal = {Phys. Rev. Res.}, volume = {2}, number = {4}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, abstract = {{Rigorous quantum scattering calculations on ultracold molecular collisions in external fields present an outstanding computational problem due to strongly anisotropic atom-molecule interactions that depend on the relative orientation of the collision partners, as well as on their vibrational degrees of freedom. Here, we present the first numerically exact three-dimensional quantum scattering calculations on strongly anisotropic atom-molecule (Li + CaH) collisions in an external magnetic field based on the parity-adapted total angular momentum representation and a new three-dimensional potential energy surface for the triplet Li-CaH collision complex developed using the unrestricted coupled-cluster method with single, double, and perturbative triple excitations and a large quadruple-zeta-type basis set. We find that while the full three-dimensional treatment is necessary for the accurate description of cold Li(M-S = 1/2) + CaH(v = 0}, doi = {10.1103/PhysRevResearch.2.043294}, author = {Morita, Masato and Klos, Jacek and Tscherbul, V, Timur} } @article {zhu_generation_2020, title = {Generation of thermofield double states and critical ground states with a quantum computer}, journal = {Proc. Natl. Acad. Sci. U. S. A.}, volume = {117}, number = {41}, year = {2020}, note = {Place: 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA Publisher: NATL ACAD SCIENCES Type: Article}, month = {oct}, pages = {25402{\textendash}25406}, abstract = {Finite-temperature phases of many-body quantum systems are fundamental to phenomena ranging from condensed-matter physics to cosmology, yet they are generally difficult to simulate. Using an ion trap quantum computer and protocols motivated by the quantum approximate optimization algorithm (QAOA), we generate nontrivial thermal quantum states of the transversefield Ising model (TFIM) by preparing thermofield double states at a variety of temperatures. We also prepare the critical state of the TFIM at zero temperature using quantum?classical hybrid optimization. The entanglement structure of thermofield double and critical states plays a key role in the study of black holes, and our work simulates such nontrivial structures on a quantum computer. Moreover, we find that the variational quantum circuits exhibit noise thresholds above which the lowest-depth QAOA circuits provide the best results.}, keywords = {Ising model, quantum computing, quantum simulation, thermofield double state, trapped ions}, issn = {0027-8424}, doi = {10.1073/pnas.2006337117}, author = {Zhu, D. and Johri, S. and Linke, N. M. and Landsman, K. A. and Alderete, C. Huerta and Nguyen, N. H. and Matsuura, A. Y. and Hsieh, T. H. and Monroe, C.} } @article { ISI:000506582800005, title = {Generic quantized zero-bias conductance peaks in superconductor-semiconductor hybrid structures}, journal = {Phys. Rev. B}, volume = {101}, number = {2}, year = {2020}, month = {JAN 8}, pages = {024506}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We show theoretically that quantized zero-bias conductance peaks should be ubiquitous in superconductor-semiconductor hybrids by employing a zero-dimensional random matrix model with continuous tuning parameters. We demonstrate that a normal metal-superconductor (NS) junction conductance spectra can be generically obtained in this model replicating all features seen in recent experimental results. The theoretical quantized conductance peaks, which explicitly do not arise from spatially isolated Majorana zero modes, are easily found by preparing a contour plot of conductance over several independent tuning parameters, mimicking the effect of Zeeman splitting and voltages on gates near the junction. This suggests that, even stable apparently quantized conductance peaks need not correspond to isolated Majorana modes; rather, the a priori expectation should be that such quantized peaks generically occupy a significant fraction of the high-dimensional tuning parameter space that characterizes the NS tunneling experiments.

}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.024506}, author = {Pan, Haining and Cole, William S. and Sau, Jay D. and Das Sarma, Sankar} } @article {tenasini_giant_2020, title = {Giant anomalous {Hall} effect in quasi-two-dimensional layered antiferromagnet {Co1}/{3NbS2}}, journal = {Phys. Rev. Res.}, volume = {2}, number = {2}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {apr}, abstract = {The discovery of the anomalous Hall effect (AHE) in bulk metallic antiferromagnets (AFMs) motivates the search of the same phenomenon in two-dimensional (2D) systems, where a quantized anomalous Hall conductance can, in principle, be observed. Here we present experiments on microfabricated devices based on Co1/3NbS2, a layered AFM that was recently found to exhibit AHE in bulk crystals below the Neel temperature T-N = 29 K. Transport measurements reveal a pronounced resistivity anisotropy, indicating that upon lowering temperature the electronic coupling between individual atomic layers is increasingly suppressed. The experiments also show an extremely large anomalous Hall conductivity of approximately 400 S/cm, more than one order of magnitude larger than in the bulk, which demonstrates the importance of studying the AHE in small exfoliated crystals, less affected by crystalline defects. Interestingly, the corresponding anomalous Hall conductance, when normalized to the number of contributing atomic planes, is similar to 0.6 e(2)/h per layer, approaching the value expected for the quantized anomalous Hall effect. The observed strong anisotropy of transport and the very large anomalous Hall conductance per layer make the properties of Co1/3NbS2 compatible with the presence of partially filled topologically nontrivial 2D bands originating from the magnetic superstructure of the antiferromagnetic state. Isolating atomically thin layers of this material and controlling their charge density may therefore provide a viable route to reveal the occurrence of the quantized AHE in a 2D AFM.

}, doi = {10.1103/PhysRevResearch.2.023051}, author = {Tenasini, Giulia and Martino, Edoardo and Ubrig, Nicolas and Ghimire, Nirmal J. and Berger, Helmuth and Zaharko, Oksana and Wu, Fengcheng and Mitchell, J. F. and Martin, Ivar and Forro, Laszlo and Morpurgo, Alberto F.} } @article { ISI:000524530000001, title = {Ground-state energy estimation of the water molecule on a trapped-ion quantum computer}, journal = {npj Quantum Inform.}, volume = {6}, number = {1}, year = {2020}, month = {APR 3}, pages = {33}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {Quantum computing leverages the quantum resources of superposition and entanglement to efficiently solve computational problems considered intractable for classical computers. Examples include calculating molecular and nuclear structure, simulating strongly interacting electron systems, and modeling aspects of material function. While substantial theoretical advances have been made in mapping these problems to quantum algorithms, there remains a large gap between the resource requirements for solving such problems and the capabilities of currently available quantum hardware. Bridging this gap will require a co-design approach, where the expression of algorithms is developed in conjunction with the hardware itself to optimize execution. Here we describe an extensible co-design framework for solving chemistry problems on a trapped-ion quantum computer and apply it to estimating the ground-state energy of the water molecule using the variational quantum eigensolver (VQE) method. The controllability of the trapped-ion quantum computer enables robust energy estimates using the prepared VQE ansatz states. The systematic and statistical errors are comparable to the chemical accuracy, which is the target threshold necessary for predicting the rates of chemical reaction dynamics, without resorting to any error mitigation techniques based on Richardson extrapolation.}, doi = {10.1038/s41534-020-0259-3}, author = {Nam, Yunseong and Chen, Jwo-Sy and Pisenti, Neal C. and Wright, Kenneth and Delaney, Conor and Maslov, Dmitri and Brown, Kenneth R. and Allen, Stewart and Amini, Jason M. and Apisdorf, Joel and Beck, Kristin M. and Blinov, Aleksey and Chaplin, Vandiver and Chmielewski, Mika and Collins, Coleman and Debnath, Shantanu and Hudek, Kai M. and Ducore, Andrew M. and Keesan, Matthew and Kreikemeier, Sarah M. and Mizrahi, Jonathan and Solomon, Phil and Williams, Mike and Wong-Campos, Jaime David and Moehring, David and Monroe, Christopher and Kim, Jungsang} } @article { ISI:000535764500019, title = {Guiding and confining of light in a two-dimensional synthetic space using electric fields}, journal = {Optica}, volume = {7}, number = {5}, year = {2020}, month = {MAY 20}, pages = {506-513}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {Synthetic dimensions provide a promising platform for photonic quantum simulations. Manipulating the flow of photons in these dimensions requires an electric field. However, photons do not have charge and do not directly interact with electric fields. Therefore, alternative approaches are needed to realize electric fields in photonics. One approach is to use engineered gauge fields that can mimic the effect of electric fields and produce the same dynamical behavior. Here, we demonstrate such an electric field for photons propagating in a two-dimensional synthetic space. Generation of electric fields in a two-dimensional synthetic lattice provides the possibility to guide photons and to trap them through the creation of quantum confined structures. We achieve this using a linearly time-varying gauge field generated by direction-dependent phase modulations. We show that the generated electric field leads to Bloch oscillations and the revival of the state after a certain number of steps dependent on the field strength. We measure the probability of the revival and demonstrate a good agreement between the observed values and the theoretically predicted results. Furthermore, by applying a nonuniform electric field, we show the possibility of waveguiding photons. Ultimately, our results open up new opportunities for manipulating the propagation of photons with potential applications in photonic quantum simulations. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {2334-2536}, doi = {10.1364/OPTICA.386347}, author = {Chalabi, Hamidreza and Barik, Sabyasachi and Mittal, Sunil and Murphy, Thomas E. and Hafezi, Mohammad and Waks, Edo} } @article {16891, title = {Hierarchy of Linear Light Cones with Long-Range Interactions}, journal = {Phys. Rev. X}, volume = {10}, year = {2020}, month = {Jul}, pages = {031009}, doi = {10.1103/PhysRevX.10.031009}, url = {https://link.aps.org/doi/10.1103/PhysRevX.10.031009}, author = {Tran, Minh C. and Chen, Chi-Fang and Ehrenberg, Adam and Guo, Andrew Y. and Deshpande, Abhinav and Hong, Yifan and Gong, Zhe-Xuan and Gorshkov, Alexey V. and Lucas, Andrew} } @article { ISI:000562320800002, title = {Higgs-like modes in two-dimensional spatially indirect exciton condensates}, journal = {Phys. Rev. B}, volume = {102}, number = {7}, year = {2020}, month = {AUG 25}, pages = {075136}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Higgs-like modes in condensed-matter physics have drawn attention because of analogies to the Higgs bosons of particle physics. Here we use a microscopic time-dependent mean-field theory to study the collective mode spectra of two-dimensional spatially indirect exciton (electron-hole pair) condensates, focusing on the Higgs-like modes, i.e., those that have a large weight in electron-hole pair amplitude response functions. We find that in the low exciton density (Bose-Einstein condensate) limit, the dominant Higgs-like modes of spatially indirect exciton condensates correspond to adding electron-hole pairs that are orthogonal to the condensed pair state. We comment on the previously studied Higgs-like collective excitations of superconductors in light of this finding.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.075136}, author = {Xue, Fei and Wu, Fengcheng and MacDonald, A. H.} } @conference {singh_high-q_2020, title = {High-{Q} {Nanomechanical} {Resonators} for {Optomechanical} {Sensing} {Beyond} the {Standard} {Quantum} {Limit}}, booktitle = {Conference on Lasers and Electro-Optics (CLEO)}, series = {Conference on {Lasers} and {Electro}-{Optics}}, year = {2020}, note = {Backup Publisher: IEEE ISSN: 2160-9020 Type: Proceedings Paper}, publisher = {IEEE}, organization = {IEEE}, abstract = {We fabricate high-stress silicon and silicon-nitride based nanomechanical string resonators to study quantum optomechanical interactions. We use phononic band-gap engineering techniques to minimize mechanical energy dissipation in the out-of-plane defect mode of the resonator. (C) 2020 The Author(s)

}, isbn = {978-1-943580-76-7}, author = {Singh, Robinjeet and Purdy, Thomas P.} } @article {kuehn_high_2020, title = {High {Resolution} {Photoexcitation} {Measurements} {Exacerbate} the {Long}-{Standing} {Fe} {XVII} {Oscillator} {Strength} {Problem}, journal = {Phys. Rev. Lett.}, volume = {124}, number = {22}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jun}, abstract = {For more than 40 years, most astrophysical observations and laboratory studies of two key soft x-ray diagnostic 2p - 3d transitions, 3C and 3D, in Fe XVII ions found oscillator strength ratios f(3C)/f(3D) disagreeing with theory, but uncertainties had precluded definitive statements on this much studied conundrum. Here, we resonantly excite these lines using synchrotron radiation at PETRA III, and reach, at a millionfold lower photon intensities, a 10 times higher spectral resolution, and 3 times smaller uncertainty than earlier work. Our final result of f(3C)/f(3D) = 3.09(8)(6) supports many of the earlier clean astrophysical and laboratory observations, while departing by five sigmas from our own newest large-scale ab initio calculations, and excluding all proposed explanations, including those invoking nonlinear effects and population transfers.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.124.225001}, author = {Kuehn, Steffen and Shah, Chintan and Lopez-Urrutia, Jose R. Crespo and Fujii, Keisuke and Steinbruegge, Rene and Stierhof, Jakob and Togawa, Moto and Harman, Zoltan and Oreshkina, Natalia S. and Cheung, Charles and Kozlov, Mikhail G. and Porsev, Sergey G. and Safronova, Marianna S. and Berengut, Julian C. and Rosner, Michael and Bissinger, Matthias and Ballhausen, Ralf and Hell, Natalie and Park, SungNam and Chung, Moses and Hoesch, Moritz and Seltmann, Joern and Surzhykov, Andrey S. and Yerokhin, Vladimir A. and Wilms, Joern and Porter, F. Scott and Stoehlker, Thomas and Keitel, Christoph H. and Pfeifer, Thomas and Brown, V, Gregory and Leutenegger, Maurice A. and Bernitt, Sven} } @article { ISI:000565455100005, title = {Higher-order topological Dirac superconductors}, journal = {Phys. Rev. B}, volume = {102}, number = {9}, year = {2020}, month = {SEP 3}, pages = {094503}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We introduce higher-order topological Dirac superconductor (HOTDSC) as a gapless topological phase of matter in three dimensions, which extends the notion of Dirac phase to a higher-order topological version. Topologically distinct from the traditional topological superconductors and known Dirac superconductors, a HOTDSC features Majorana hinge modes between adjacent surfaces, which are direct consequences of the symmetry-protected higher-order band topology manifesting in the system. Specifically, we show that rotational, spatial inversion, and time-reversal symmetries together protect the coexistence of bulk Dirac nodes and hinge Majorana modes in a seamless way. We define a set of topological indices that fully characterizes the HOTDSC. We further show that a practical way to realize the HOTDSC phase is to introduce unconventional odd-parity pairing to a three-dimensional Dirac semimetal while preserving the necessary symmetries. As a concrete demonstration of our idea, we construct a corresponding minimal lattice model for HOTDSC obeying the symmetry constraints. Our model exhibits the expected topological invariants in the bulk and the defining spectroscopic features on an open geometry, as we explicitly verify both analytically and numerically. Remarkably, the HOTDSC phase offers an example of a {\textquoteleft}{\textquoteleft}higher-order topological quantum critical point, which enables realizations of various higher-order topological phases under different symmetry-breaking patterns. In particular, by breaking the inversion symmetry of a HOTDSC, we arrive at a higher-order Weyl superconductor, which is yet another gapless topological state that exhibits hybrid higher-order topology.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.094503}, author = {Zhang, Rui-Xing and Hsu, Yi-Ting and Das Sarma, S.} } @article { ISI:000535205600016, title = {Hilbert-Space Fragmentation from Strict Confinement}, journal = {Phys. Rev. Lett.}, volume = {124}, number = {20}, year = {2020}, month = {MAY 22}, pages = {207602}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study one-dimensional spin-1/2 models in which strict confinement of Ising domain walls leads to the fragmentation of Hilbert space into exponentially many disconnected subspaces. Whereas most previous works emphasize dipole moment conservation as an essential ingredient for such fragmentation, we instead require two commuting U(1) conserved quantities associated with the total domain-wall number and the total magnetization. The latter arises naturally from the confinement of domain walls. Remarkably, while some connected components of the Hilbert space thermalize, others are integrable by Bethe ansatz. We further demonstrate how this Hilbert-space fragmentation pattern arises perturbatively in the confining limit of Z(2) gauge theory coupled to fermionic matter, leading to a hierarchy of timescales for motion of the fermions. This model can be realized experimentally in two complementary settings.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.124.207602}, author = {Yang, Zhi-Cheng and Liu, Fangli and Gorshkov, V, Alexey and Iadecola, Thomas} } @article {chou_hofstadter_2020, title = {Hofstadter butterfly and {Floquet} topological insulators in minimally twisted bilayer graphene}, journal = {Phys. Rev. Res.}, volume = {2}, number = {3}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {aug}, abstract = {We theoretically study the Hofstadter butterfly of a triangular network model in minimally twisted bilayer graphene. The band structure manifests periodicity in energy, mimicking that of Floquet systems. The butterfly diagrams provide fingerprints of the model parameters and reveal the hidden band topology. In a strong magnetic field, we establish that minimally twisted bilayer graphene realizes low-energy Floquet topological insulators (FTIs) carrying zero Chern number, while hosting chiral edge states in bulk gaps. We identify the FTIs by analyzing the nontrivial spectral flow in the Hofstadter butterfly, and by explicitly computing the chiral edge states. Our theory paves the way for an effective practical realization of FTIs in equilibrium solid-state systems.}, doi = {10.1103/PhysRevResearch.2.033271}, author = {Chou, Yang-Zhi and Wu, Fengcheng and Das Sarma, Sankar} } @article {elshaari_hybrid_2020, title = {Hybrid integrated quantum photonic circuits}, journal = {Nat. Photonics}, volume = {14}, number = {5}, year = {2020}, note = {Place: MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND Publisher: NATURE PUBLISHING GROUP Type: Review}, month = {may}, pages = {285{\textendash}298}, abstract = {The Review summarizes the progress of hybrid quantum photonics integration in terms of its important design considerations and fabrication approaches, and highlights some successful realizations of key physical resources for building integrated quantum devices, such as quantum teleporters, quantum repeaters and quantum simulators. Recent developments in chip-based photonic quantum circuits have radically impacted quantum information processing. However, it is challenging for monolithic photonic platforms to meet the stringent demands of most quantum applications. Hybrid platforms combining different photonic technologies in a single functional unit have great potential to overcome the limitations of monolithic photonic circuits. Our Review summarizes the progress of hybrid quantum photonics integration, discusses important design considerations, including optical connectivity and operation conditions, and highlights several successful realizations of key physical resources for building a quantum teleporter. We conclude by discussing the roadmap for realizing future advanced large-scale hybrid devices, beyond the solid-state platform, which hold great potential for quantum information applications.}, issn = {1749-4885}, doi = {10.1038/s41566-020-0609-x}, author = {Elshaari, Ali W. and Pernice, Wolfram and Srinivasan, Kartik and Benson, Oliver and Zwiller, Val} } @article { ISI:000528219500006, title = {Hybrid integration methods for on-chip quantum photonics}, journal = {Optica}, volume = {7}, number = {4}, year = {2020}, month = {APR 20}, pages = {291-308}, publisher = {OPTICAL SOC AMER}, type = {Review}, abstract = {The goal of integrated quantum photonics is to combine components for the generation, manipulation, and detection of nonclassical light in a phase-stable and efficient platform. Solid-state quantum emitters have recently reached outstanding performance as single-photon sources. In parallel, photonic integrated circuits have been advanced to the point that thousands of components can be controlled on a chip with high efficiency and phase stability. Consequently, researchers are now beginning to combine these leading quantum emitters and photonic integrated circuit platforms to realize the best properties of each technology. In this paper, we review recent advances in integrated quantum photonics based on such hybrid systems. Although hybrid integration solves many limitations of individual platforms, it also introduces new challenges that arise from interfacing different materials. We review various issues in solid-state quantum emitters and photonic integrated circuits, the hybrid integration techniques that bridge these two systems, and methods for chip-based manipulation of photons and emitters. Finally, we discuss the remaining challenges and future prospects of on-chip quantum photonics with integrated quantum emitters. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {2334-2536}, doi = {10.1364/OPTICA.384118}, author = {Kim, Je-Hyung and Aghaeimeibodi, Shahriar and Carolan, Jacques and Englund, Dirk and Waks, Edo} } @article {zhiqiang_hyperfine-mediated_2020, title = {Hyperfine-mediated effects in a {Lu}+ optical clock}, journal = {Phys. Rev. A}, volume = {102}, number = {5}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {nov}, abstract = {We consider hyperfine-mediated effects for clock transitions in Lu-176(+). Mixing of fine-structure levels due to the hyperfine interaction brings about modifications to the Lande g-factors and the quadrupole moment for a given state. Explicit expressions are derived for both the g-factor and quadrupole corrections, for which leading-order terms arise from the nuclear magnetic dipole coupling. High accuracy measurements of the g-factors for the S-1(0) and D-3(1) hyperfine levels are carried out, and they provide an experimental determination of the leading-order correction terms.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.102.052834}, author = {Zhiqiang, Zhang and Arnold, K. J. and Kaewuam, R. and Safronova, M. S. and Barrett, M. D.} } @article {16901, title = {Imaging viscous flow of the Dirac fluid in graphene}, journal = {Nature}, volume = {583}, year = {2020}, month = {Jul}, pages = {537-541}, abstract = {The electron{\textendash}hole plasma in charge-neutral graphene is predicted to realize a quantum critical system in which electrical transport features a universal hydrodynamic description, even at room temperature1,2. This quantum critical {\textquoteleft}Dirac fluid{\textquoteright} is expected to have a shear viscosity close to a minimum bound3,4, with an interparticle scattering rate saturating1 at the Planckian time, the shortest possible timescale for particles to relax. Although electrical transport measurements at finite carrier density are consistent with hydrodynamic electron flow in graphene5{\textendash}8, a clear demonstration of viscous flow at the charge-neutrality point remains elusive. Here we directly image viscous Dirac fluid flow in graphene at room temperature by measuring the associated stray magnetic field. Nanoscale magnetic imaging is performed using quantum spin magnetometers realized with nitrogen vacancy centres in diamond. Scanning single-spin and wide-field magnetometry reveal a parabolic Poiseuille profile for electron flow in a high-mobility graphene channel near the charge-neutrality point, establishing the viscous transport of the Dirac fluid. This measurement is in contrast to the conventional uniform flow profile imaged in a metallic conductor and also in a low-mobility graphene channel. Via combined imaging and transport measurements, we obtain viscosity and scattering rates, and observe that these quantities are comparable to the universal values expected at quantum criticality. This finding establishes a nearly ideal electron fluid in charge-neutral, high-mobility graphene at room temperature4. Our results will enable the study of hydrodynamic transport in quantum critical fluids relevant to strongly correlated electrons in high-temperature superconductors9. This work also highlights the capability of quantum spin magnetometers to probe correlated electronic phenomena at the nanoscale.

}, issn = {1476-4687}, doi = {10.1038/s41586-020-2507-2}, url = {https://doi.org/10.1038/s41586-020-2507-2}, author = {Ku, Mark J. H. and Zhou, Tony X. and Li, Qing and Shin, Young J. and Shi, Jing K. and Burch, Claire and Anderson, Laurel E. and Pierce, Andrew T. and Xie, Yonglong and Hamo, Assaf and Vool, Uri and Zhang, Huiliang and Casola, Francesco and Taniguchi, Takashi and Watanabe, Kenji and Fogler, Michael M. and Kim, Philip and Yacoby, Amir and Walsworth, Ronald L.} } @article {li_improved_2020, title = {Improved coupled-mode theory for high-index-contrast photonic platforms}, journal = {Phys. Rev. A}, volume = {102}, number = {6}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {dec}, abstract = {Coupled-mode theory (CMT) has been widely used in optics and photonics design. Despite its popularity, several different formulations of CMT exist in the literature, and their applicable range is not entirely clear, in particular when it comes to high-index-contrast photonics platforms. Here we propose an improved formulation of CMT and demonstrate its superior performance through numerical simulations that compare CMT-derived quantities with supermode calculations and full wave propagation simulations. In particular, application of the improved CMT to asymmetric waveguides reveals a necessary correction in the conventional phase matching condition for high-index-contrast systems, which could lead to more accurate photonic circuit designs involving asymmetric elements.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.102.063506}, author = {Li, Qing and Moille, Gregory and Taheri, Hossein and Adibi, Ali and Srinivasan, Kartik} } @article {hwang_impurity-scattering-induced_2020, title = {Impurity-scattering-induced carrier transport in twisted bilayer graphene}, journal = {Phys. Rev. Res.}, volume = {2}, number = {1}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {mar}, abstract = {We theoretically calculate the impurity-scattering-induced resistivity of twisted bilayer graphene at low twist angles where the graphene Fermi velocity is strongly suppressed. We consider, as a function of carrier density, twist angle, and temperature, both long-ranged Coulomb scattering and short-ranged defect scattering within a Boltzmann theory relaxation time approach. For experimentally relevant disorder, impurity scattering contributes a resistivity comparable to (much larger than) the phonon scattering contribution at high (low) temperatures. Decreasing twist angle leads to larger resistivity, and in general, the resistivity increases (decreases) with increasing temperature (carrier density). Inclusion of the van Hove singularity in the theory leads to a strong increase in the resistivity at higher densities, where the chemical potential is close to a van Hove singularity, leading to an apparent density-dependent plateau-type structure in the resistivity, which has been observed in recent transport experiments. We also show that the Matthiessen{\textquoteright}s rule is strongly violated in twisted bilayer graphene at low twist angles.}, doi = {10.1103/PhysRevResearch.2.013342}, author = {Hwang, E. H. and Das Sarma, S.} } @article { ISI:000522116800007, title = {Incorporating the Stern-Gerlach delayed-choice quantum eraser into the undergraduate quantum mechanics curriculum}, journal = {Am. J. Phys.}, volume = {88}, number = {4}, year = {2020}, month = {APR}, pages = {298-307}, publisher = {AMER INST PHYSICS}, type = {Article}, abstract = {As {\textquoteleft}{\textquoteleft}Stern-Gerlach first{{\textquoteright}{\textquoteright}} becomes increasingly popular in the undergraduate quantum mechanics curriculum, we show how one can extend the treatment found in conventional textbooks to cover some exciting new quantum phenomena. Namely, we illustrate how one can describe a delayed choice variant of the quantum eraser which is realized within the Stern-Gerlach framework. Covering this material allows the instructor to reinforce notions of changes in basis functions, quantum superpositions, quantum measurements, and the complementarity principle as expressed in whether we know {\textquoteleft}{\textquoteleft}which-way{{\textquoteright}{\textquoteright}} information or not. It also allows the instructor to dispel common misconceptions of when a measurement occurs and when a system is in a superposition of states.}, issn = {0002-9505}, doi = {10.1119/10.0000519}, author = {Courtney, William F. and Vieira, Lucas B. and Julienne, Paul S. and Freericks, James K.} } @article { ISI:000575024200001, title = {Infrared fixed points of higher-spin fermions in topological semimetals}, journal = {Phys. Rev. B}, volume = {102}, number = {15}, year = {2020}, month = {OCT 5}, pages = {155104}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We determine the fate of interacting fermions described by the Hamiltonian H = p . J in three-dimensional topological semimetals with linear band crossing, where p is momentum and J are the spin- j matrices for half-integer pseudospin j >= 3/2. While weak short-range interactions are irrelevant at the crossing point due to the vanishing density of states, weak long-range Coulomb interactions lead to a renormalization of the band structure. Using a self-consistent perturbative renormalization group approach, we show that band crossings of the type p . J are unstable for j >= 7/2. Instead, through an intriguing interplay between cubic crystal symmetry, band topology, and interaction effects, the system is attracted to a variety of infrared fixed points. We also unravel several other properties of higher-spin fermions for general j, such as the relation between fermion self-energy and free energy, or the vanishing of the renormalized charge. An O(3) symmetric fixed point composed of equal chirality Weyl fermions is stable for j <= 7/2 and very likely so for all j. We then explore the rich fixed point structure for j = 5/2 in detail. We find additional attractive fixed points with enhanced 0(3) symmetry that host both emergent Weyl or massless Dirac fermions, and identify a puzzling, infrared stable, anisotropic fixed point without enhanced symmetry in close analogy to the known case of j = 3/2.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.155104}, author = {Boettcher, Igor} } @article {16956, title = {Instantaneous braids and Dehn twists in topologically ordered states}, journal = {Phys. Rev. B}, volume = {102}, year = {2020}, month = {Aug}, pages = {075105}, doi = {10.1103/PhysRevB.102.075105}, url = {https://link.aps.org/doi/10.1103/PhysRevB.102.075105}, author = {Zhu, Guanyu and Lavasani, Ali and Barkeshli, Maissam} } @conference {rao_integrated_2020, title = {Integrated {Photonic} {Interposers} for {Processing} {Octave}-{Spanning} {Microresonator} {Frequency} {Combs}}, booktitle = {Conference on Lasers and Electro-Optics (CLEO)}, series = {Conference on {Lasers} and {Electro}-{Optics}}, year = {2020}, note = {Backup Publisher: IEEE ISSN: 2160-9020 Type: Proceedings Paper}, publisher = {IEEE}, organization = {IEEE}, abstract = {We demonstrate multiple silicon-nitride nanophotonic elements for on-chip processing of octave-spanning microresonator frequency combs. Dichroic filters, multimode interferometers, and tunable add-drop microring filters are shown along with soliton microcombs generated on a bilayer photonic chip. (C) 2020 The Author(s)

}, isbn = {978-1-943580-76-7}, author = {Rao, Ashutosh and Moille, Gregory and Lu, Xiyuan and Sacchetto, Davide and Geiselmann, Michael and Zervas, Michael and Papp, Scott and Bowers, John and Srinivasan, Kartik} } @conference {dutta_integrated_2020, title = {An {Integrated} {Photonic} {Platform} for {Rare}-{Earth} {Ions} in {Thin} {Film} {Lithium} {Niobate}}, booktitle = {Conference on Lasers and Electro-Optics (CLEO)}, series = {Conference on {Lasers} and {Electro}-{Optics}}, year = {2020}, note = {Backup Publisher: IEEE ISSN: 2160-9020 Type: Proceedings Paper}, publisher = {IEEE}, organization = {IEEE}, abstract = {We demonstrate an integrated photonic platform for rare earth ions in thin film lithium niobate. The ions in the thin film retain bulk like optical properties. This paves way for a new generation of highly scalable, active optoelectronic devices with applications to both classical and quantum optics. (C) 2020 The Author(s)

}, isbn = {978-1-943580-76-7}, author = {Dutta, Subhojit and Goldschmidt, Elizabeth A. and Barik, Sabyasachi and Saha, Uday and Waks, Edo} } @article { ISI:000507151600097, title = {Integrated Photonic Platform for Rare-Earth Ions in Thin Film Lithium Niobate}, journal = {Nano Lett.}, volume = {20}, number = {1}, year = {2020}, month = {JAN}, pages = {741-747}, publisher = {AMER CHEMICAL SOC}, type = {Article}, abstract = {Rare-earth ion ensembles doped in single crystals are a promising materials system with widespread applications in optical signal processing, lasing, and quantum information processing. Incorporating rare-earth ions into integrated photonic devices could enable compact lasers and modulators, as well as on-chip optical quantum memories for classical and quantum optical applications. To this end, a thin film single crystalline wafer structure that is compatible with planar fabrication of integrated photonic devices would be highly desirable. However, incorporating rare-earth ions into a thin film form-factor while preserving their optical properties has proven challenging. We demonstrate an integrated photonic platform for rare-earth ions doped in a single crystalline thin film lithium niobate on insulator. The thin film is composed of lithium niobate doped with Tm3+. The ions in the thin film exhibit optical lifetimes identical to those measured in bulk crystals. We show narrow spectral holes in a thin film waveguide that require up to 2 orders of magnitude lower power to generate than previously reported bulk waveguides. Our results pave the way for scalable on-chip lasers, optical signal processing devices, and integrated optical quantum memories.}, keywords = {integrated photonics, optical signal processing, Rare-earth ions, spectral hole burning quantum information processing, thin film lithium niobate}, issn = {1530-6984}, doi = {10.1021/acs.nanolett.9b04679}, author = {Dutta, Subhojit and Goldschmidt, Elizabeth A. and Barik, Sabyasachi and Saha, Uday and Waks, Edo} } @article {hu_interacting_2020, title = {Interacting topological mirror excitonic insulator in one dimension}, journal = {Phys. Rev. B}, volume = {102}, number = {23}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {dec}, abstract = {We introduce the topological mirror excitonic insulator as a new type of interacting topological crystalline phase in one dimension. Its mirror-symmetry-protected topological properties are driven by exciton physics, and it manifests in the quantized bulk polarization and half-charge modes on the boundary. And the bosonization analysis is performed to demonstrate its robustness against strong correlation effects in one dimension. Besides, we also show that Rashba nanowires and Dirac semimetal nanowires could provide ideal experimental platforms to realize this new topological mirror excitonic insulating state. Its experimental consequences, such as quantized tunneling conductance in the tunneling measurement, are also discussed.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.235115}, author = {Hu, Lun-Hui and Zhang, Rui-Xing and Zhang, Fu-Chun and Wu, Congjun} } @article {16681, title = {Interplay of Topology and Electron-Electron Interactions in Rarita-Schwinger-Weyl semimetals}, journal = {Phys. Rev. Lett.}, volume = {124}, year = {2020}, month = {Mar}, pages = {127602}, abstract = {We study, for the first time, the effects of strong short-range electron-electron interactions in generic Rarita-Schwinger-Weyl semimetals hosting spin-3/2\ electrons with linear dispersion at a fourfold band crossing point. The emergence of this novel quasiparticle, which is absent in high-energy physics, has recently been confirmed experimentally in the solid state. We combine symmetry considerations and a perturbative renormalization group analysis to discern three interacting phases that are prone to emerge in the strongly correlated regime: The chiral topological semimetal breaks a\ Z2\ symmetry and features four Weyl nodes of monopole charge\ +1\ located at vertices of a tetrahedron in momentum space. The\ s-wave superconducting state opens a Majorana mass gap for the fermions and is the leading superconducting instability. The Weyl semimetal phase removes the fourfold degeneracy and creates two Weyl nodes with either equal or opposite chirality depending on the anisotropy of the band structure. We find that symmetry breaking occurs at weaker coupling if the total monopole charge remains constant across the transition.

}, doi = {10.1103/PhysRevLett.124.127602}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.124.127602}, author = {Boettcher, Igor} } @article { ISI:000562003800006, title = {Inversion-protected Higher-order Topological Superconductivity in Monolayer WTe2}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {9}, year = {2020}, month = {AUG 24}, pages = {097001}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Monolayer WTe2, a centrosymmetric transition metal dichacogenide, has recently been established as a quantum spin Hall insulator and found superconducting upon gating. Here we study the pairing symmetry and topological nature of superconducting WTe2 with a microscopic model at mean-field level. Surprisingly, we find that the spin-triplet phases in our phase diagram all host Majorana modes localized on two opposite corners. Even when the conventional pairing is favored, we find that an intermediate inplane magnetic field exceeding the Pauli limit stabilizes an unconventional equal-spin pairing aligning with the field, which also hosts Majorana corner modes. Motivated by our findings, we obtain a recipe for two-dimensional superconductors featuring {\textquoteleft}{\textquoteleft}higher-order topology{{\textquoteright}{\textquoteright}} from the boundary perspective. Generally, a superconducting inversion-symmetric quantum spin Hall material whose normal-state Fermi surface is away from high-symmetry points, such as gated monolayer WTe2, hosts Majorana corner modes if the superconductivity is parity-odd. We further point out that this higher-order phase is an inversion-protected topological crystalline superconductor and study the bulk-boundary correspondence. Finally, we discuss possible experiments for probing the Majorana corner modes. Our findings suggest superconducting monolayer WTe, is a playground for higher-order topological superconductivity and possibly the first material realization for inversion-protected Majorana corner modes without utilizing proximity effect.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.097001}, author = {Hsu, Yi-Ting and Cole, William S. and Zhang, Rui-Xing and Sau, Jay D.} } @conference {sabines-chesterking_klyshko_2020, title = {Klyshko efficiency optimization using a genetic algorithm}, booktitle = {Conference on Lasers and Electro-Optics (CLEO)}, series = {Conference on {Lasers} and {Electro}-{Optics}}, year = {2020}, note = {Backup Publisher: IEEE ISSN: 2160-9020 Type: Proceedings Paper}, publisher = {IEEE}, organization = {IEEE}, address = {Conference on Lasers and Electro-Optics (CLEO)}, abstract = {We use a spatial light modulator and a genetic algorithm to manipulate the spatial profile of the pump beam of a down-conversion source in order to improve its Klyshko efficiency. (c) 2020 The Author(s)

}, isbn = {978-1-943580-76-7}, author = {Sabines-Chesterking, Javier and Moreau, Paul-Antoine and McMillan, Alex and Fickler, Robert and Rarity, John and Matthews, Jonathan} } @article {pasnoori_kondo_2020, title = {Kondo impurity at the edge of a superconducting wire}, journal = {Phys. Rev. Res.}, volume = {2}, number = {1}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jan}, abstract = {Quantum impurity models are prevalent throughout many body physics, providing some prime examples of strongly correlated systems. Aside from being of great interest in themselves, they can provide deep insight into the effects of strong correlations in general. The classic example is the Kondo model wherein a magnetic impurity is screened at low energies by a noninteracting metallic bath. Here we consider a magnetic impurity coupled to a quantum wire with pairing interaction which dynamically generates a mass gap. Using Bethe ansatz, we solve the system exactly finding that it exhibits both screened and unscreened phases for an antiferromagnetic impurity. We determine the ground-state density of states and magnetization in both phases as well as the excitations. In contrast to the well studied case of magnetic impurities in superconductors, we find that there are no intragap bound states in the spectrum. The phase transition is not associated to a level crossing but with quantum fluctuations.}, doi = {10.1103/PhysRevResearch.2.013006}, author = {Pasnoori, Parameshwar R. and Rylands, Colin and Andrei, Natan} } @article {jian_landau_2020, title = {Landau poles in condensed matter systems}, journal = {Phys. Rev. Res.}, volume = {2}, number = {2}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jun}, abstract = {The existence or not of Landau poles is one of the oldest open questions in nonasymptotic quantum field theories. We investigate the Landau pole issue in two condensed matter systems whose long-wavelength physics is described by appropriate quantum field theories: the critical quantum magnet and Dirac fermions in graphene with long-range Coulomb interactions. The critical quantum magnet provides a classic example of a quantum phase transition, and it is well described by the phi(4) theory. We find that the irrelevant but symmetry-allowed couplings, such as the phi(6) potential, can significantly change the fate of the Landau pole in the emergent phi(4) theory. We obtain the coupled beta functions of a phi(4) + phi(6) potential at both small and large orders. Already from the one-loop calculation, the Landau pole is replaced by an ultraviolet fixed point. A Lipatov analysis at large orders reveals that the inclusion of a phi(6) term also has important repercussions for the high-order expansion of the beta functions. We also investigate the role of the Landau pole in a very different system: Dirac fermions in 2 + 1 dimensions with long-range Coulomb interactions, e.g., graphene. Both the weak-coupling perturbation theory up to two loops and a low-order large-N calculation show the absence of a Landau pole. Furthermore, we calculate the asymptotic expansion coefficients of the beta function. We find that the asymptotic coefficient is bounded by that of a pure bosonic phi(4) theory, and consequently graphene is free from Landau poles if the pure (4) theory does not manifest a Landau pole. We briefly discuss possible experiments that could potentially probe the existence of a Landau pole in these systems. Studying Landau poles in suitable condensed matter systems is of considerable fundamental importance since the relevant Landau pole energy scales in particle physics, whether it is quantum electrodynamics or Higgs physics, are completely unattainable.}, doi = {10.1103/PhysRevResearch.2.023310}, author = {Jian, Shao-Kai and Barnes, Edwin and Das Sarma, Sankar} } @article {tsai_learning_2020, title = {Learning molecular dynamics with simple language model built upon long short-term memory neural network}, journal = {Nat. Commun.}, volume = {11}, number = {1}, year = {2020}, note = {Place: HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY Publisher: NATURE RESEARCH Type: Article}, month = {oct}, abstract = {Recurrent neural networks have led to breakthroughs in natural language processing and speech recognition. Here we show that recurrent networks, specifically long short-term memory networks can also capture the temporal evolution of chemical/biophysical trajectories. Our character-level language model learns a probabilistic model of 1-dimensional stochastic trajectories generated from higher-dimensional dynamics. The model captures Boltzmann statistics and also reproduces kinetics across a spectrum of timescales. We demonstrate how training the long short-term memory network is equivalent to learning a path entropy, and that its embedding layer, instead of representing contextual meaning of characters, here exhibits a nontrivial connectivity between different metastable states in the underlying physical system. We demonstrate our model{\textquoteright}s reliability through different benchmark systems and a force spectroscopy trajectory for multi-state riboswitch. We anticipate that our work represents a stepping stone in the understanding and use of recurrent neural networks for understanding the dynamics of complex stochastic molecular systems. Artificial neural networks have been successfully used for language recognition. Tsai et al. use the same techniques to link between language processing and prediction of molecular trajectories and show capability to predict complex thermodynamics and kinetics arising in chemical or biological physics.}, issn = {2041-1723}, doi = {10.1038/s41467-020-18959-8}, author = {Tsai, Sun-Ting and Kuo, En-Jui and Tiwary, Pratyush} } @article {kollar_line-graph_2020, title = {Line-{Graph} {Lattices}: {Euclidean} and {Non}-{Euclidean} {Flat} {Bands}, and {Implementations} in {Circuit} {Quantum} {Electrodynamics}}, journal = {Commun. Math. Phys.}, volume = {376}, number = {3}, year = {2020}, note = {Place: ONE NEW YORK PLAZA, SUITE 4600, NEW YORK, NY, UNITED STATES Publisher: SPRINGER Type: Article}, month = {jun}, pages = {1909{\textendash}1956}, abstract = {Materials science and the study of the electronic properties of solids are a major field of interest in both physics and engineering. The starting point for all such calculations is single-electron, or non-interacting, band structure calculations, and in the limit of strong on-site confinement this can be reduced to graph-like tight-binding models. In this context, both mathematicians and physicists have developed largely independent methods for solving these models. In this paper we will combine and present results from both fields. In particular, we will discuss a class of lattices which can be realized as line graphs of other lattices, both in Euclidean and hyperbolic space. These lattices display highly unusual features including flat bands and localized eigenstates of compact support. We will use the methods of both fields to show how these properties arise and systems for classifying the phenomenology of these lattices, as well as criteria for maximizing the gaps. Furthermore, we will present a particular hardware implementation using superconducting coplanar waveguide resonators that can realize a wide variety of these lattices in both non-interacting and interacting form.

}, issn = {0010-3616}, doi = {10.1007/s00220-019-03645-8}, author = {Kollar, Alicia J. and Fitzpatrick, Mattias and Sarnak, Peter and Houck, Andrew A.} } @conference {mazurek_loophole-free_2020, title = {Loophole-{Free} {Test} of {Einstein}-{Podolsky}-{Rosen} {Steering} with {One} {Bit} of {Faster}-than-{Light} {Communication}}, booktitle = {Conference on Lasers and Electro-Optics (CLEO)}, series = {Conference on {Lasers} and {Electro}-{Optics}}, year = {2020}, note = {Backup Publisher: IEEE ISSN: 2160-9020 Type: Proceedings Paper}, publisher = {IEEE}, organization = {IEEE}, abstract = {The communication cost for classically simulating Einstein-Podolsky-Rosen (EPR) steering correlations quantifies their strength. We report a loophole-free demonstration of EPR steering correlations requiring more than one faster-than-light bit to simulate. (C) 2020 The Author(s)

}, isbn = {978-1-943580-76-7}, author = {Mazurek, M. D. and Xiang, Y. and Stevens, M. J. and Bienfang, J. C. and Wayne, M. A. and Abellan, C. and Amaya, W. and Mitchell, M. W. and Mirin, R. P. and Nam, S. W. and He, Q. and Shalm, L. K. and Wiseman, H. M.} } @article { ISI:000527491100005, title = {Magic wavelength of the Ba-138(+) 6s S-2(1/2)-5d D-2(5/2) clock transition}, journal = {Phys. Rev. A}, volume = {101}, number = {4}, year = {2020}, month = {APR 22}, pages = {042507}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The zero crossing of the dynamic differential scalar polarizability of the S-1/2 - D-5/2 clock transition in Ba-138(+) has been determined to be 459.1614(28) THz. Together with previously determined matrix elements and branching ratios, this tightly constrains the dynamic differential scalar polarizability of the clock transition over a large wavelength range (greater than or similar to 700 nm). In particular, it allows an estimate of the blackbody radiation shift of the clock transition at room temperature.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.101.042507}, author = {Chanu, S. R. and Koh, V. P. W. and Arnold, K. J. and Kaewuam, R. and Tan, T. R. and Zhang, Zhiqiang and Safronova, M. S. and Barrett, M. D.} } @article {zheng_magic_2020, title = {Magic wavelengths of the {Yb} (6s(2) {S}-1(0)-6s6p {P}-3(1)) intercombination transition}, journal = {Phys. Rev. A}, volume = {102}, number = {6}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {dec}, abstract = {We calculate and measure the magic wavelengths for the 6s(2) S-1(0)-6s6p P-3(1) intercombination transition of the neutral ytterbium atom. The calculation is performed with the ab initio configuration interaction + all-order method. The measurement is done with laser spectroscopy on cold atoms in an optical dipole trap. The magic wavelengths are determined to be 1035.68(4) nm for the pi transition (Delta m = 0) and 1036.12(3) nm for the sigma transitions (vertical bar Delta m vertical bar = 1) in agreement with the calculated values. Laser cooling on the narrow intercombination transition could achieve better results for atoms in an optical dipole trap when the trap wavelength is tuned to near the magic wavelength.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.102.062805}, author = {Zheng, T. A. and Yang, Y. A. and Safronova, M. S. and Safronova, I, U. and Xiong, Zhuan-Xian and Xia, T. and Lu, Z-T} } @article { ISI:000575114800001, title = {Magic-angle semimetals}, journal = {npj Quantum Mater.}, volume = {5}, number = {1}, year = {2020}, month = {OCT 6}, pages = {71}, publisher = {NATURE RESEARCH}, type = {Article}, abstract = {Breakthroughs in two-dimensional van der Waals heterostructures have revealed that twisting creates a moire pattern that quenches the kinetic energy of electrons, allowing for exotic many-body states. We show that cold atomic, trapped ion, and metamaterial systems can emulate the effects of a twist in many models from one to three dimensions. Further, we demonstrate at larger angles (and argue at smaller angles) that by considering incommensurate effects, the magic-angle effect becomes a single-particle quantum phase transition (including in a model for twisted bilayer graphene in the chiral limit). We call these models {\textquoteleft}{\textquoteleft}magic-angle semimetals{{\textquoteright}{\textquoteright}}. Each contains nodes in the band structure and an incommensurate modulation. At magic-angle criticality, we report a nonanalytic density of states, flat bands, multifractal wave functions that Anderson delocalize in momentum space, and an essentially divergent effective interaction scale. As a particular example, we discuss how to observe this effect in an ultracold Fermi gas.}, doi = {10.1038/s41535-020-00271-9}, author = {Fu, Yixing and Konig, Elio J. and Wilson, Justin H. and Chou, Yang-Zhi and Pixley, Jedediah H.} } @article {chou_magic-angle_2020, title = {Magic-angle semimetals with chiral symmetry}, journal = {Phys. Rev. B}, volume = {101}, number = {23}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jun}, abstract = {We construct and solve a two-dimensional, chirally symmetric model of Dirac cones subjected to a quasiperiodic modulation. In real space, this is realized with a quasiperiodic hopping term. This hopping model, as we show, at the Dirac node energy has a rich phase diagram with a semimetal-to-metal phase transition at intermediate amplitude of the quasiperiodic modulation, and a transition to a phase with a diverging density of states (DOS) and subdiffusive transport when the quasiperiodic hopping is strongest. We further demonstrate that the semimetal-to-metal phase transition can be characterized by the multifractal structure of eigenstates in momentum space and can be considered as a unique {\textquotedblleft}unfreezing{\textquotedblright} transition. This unfreezing transition in momentum space generates flat bands with a dramatically renormalized bandwidth in the metallic phase similar to the phenomena of the band structure of twisted bilayer graphene at the magic angle. We characterize the nature of this transition numerically as well as analytically in terms of the formation of a band of topological zero modes. For pure quasiperiodic hopping, we provide strong numerical evidence that the low-energy DOS develops a divergence and the eigenstates exhibit Chalker (quantum-critical) scaling despite the model not being random. At particular commensurate limits the model realizes higher-order topological insulating phases. We discuss how these systems can be realized in experiments on ultracold atoms and metamaterials.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.235121}, author = {Chou, Yang-Zhi and Fu, Yixing and Wilson, Justin H. and Konig, E. J. and Pixley, J. H.} } @article { ISI:000544124500044, title = {Magnet System for the Quantum Electromechanical Metrology Suite}, journal = {IEEE Trans. Instrum. Meas.}, volume = {69}, number = {8}, year = {2020}, month = {AUG.}, pages = {5736-5744}, publisher = {IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC}, type = {Article}, abstract = {The design of the permanent magnet system for the new quantum electromechanical metrology suite (QEMMS) is described. The QEMMS, developed at the National Institute of Standards and Technology (NIST), consists of a Kibble balance, a programmable Josephson voltage standard, and a quantum Hall resistance standard. It will be used to measure masses up to 100 g with relative uncertainties below 2 x 10(-8). The magnet system is based on the design of the NIST-4 magnet system with significant changes to adopt to a smaller Kibble balance and to overcome known practical limitations. Analytical models are provided to describe the coil-current effect and model the forces required to split the magnet into two parts to install the coil. Both models are compared to simulation results obtained with finite-element analysis and measurement results. Other aspects such as the coil design and flatness of Bl profile are considered.}, keywords = {Air gaps, Force, Kibble balance, magnet circuit, magnet system, Magnetic circuits, Magnetic noise, Magnetic shielding, mass measurement, Permanent magnets, Superconducting magnets}, issn = {0018-9456}, doi = {10.1109/TIM.2019.2959852}, author = {Marangoni, Rafael R. and Haddad, Darine and Seifert, Frank and Chao, Leon S. and Newell, David B. and Schlamminger, Stephan} } @article {masson_many-body_2020, title = {Many-{Body} {Signatures} of {Collective} {Decay} in {Atomic} {Chains}}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {26}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, abstract = {Fully inverted atoms placed at exactly the same location synchronize as they deexcite, and light is emitted in a burst (known as {\textquotedblleft}Dicke{\textquoteright}s superradiance{\textquotedblright}). We investigate the role of (mite interatomic separation on correlated decay in mesoscopic chains and provide an understanding in terms of collective jump operators. We show that the superradiant burst survives at small distances, despite Hamiltonian dipole-dipole interactions. However, for larger separations, competition between different jump operators leads to dephasing, suppressing superradiance. Collective effects are still significant for arrays with lattice constants of the order of a wavelength, and lead to a photon emission rate that decays nonexponentially in time. We calculate the two-photon correlation function and demonstrate that emission is correlated and directional, as well as sensitive to small changes in the interatomic distance. These features can be measured in current experimental setups, and are robust to realistic imperfections.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.263601}, author = {Masson, Stuart J. and Ferrier-Barbut, Igor and Orozco, Luis A. and Browaeys, Antoine and Asenjo-Garcia, Ana} } @article { ISI:000570982600002, title = {Many-Body Dephasing in a Trapped-Ion Quantum Simulator}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {12}, year = {2020}, month = {SEP 18}, pages = {120605}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {How a closed interacting quantum many-body system relaxes and dephases as a function of time is a fundamental question in thermodynamic and statistical physics. In this Letter, we analyze and observe the persistent temporal fluctuations after a quantum quench of a tunable long-range interacting transverse-field Ising Hamiltonian realized with a trapped-ion quantum simulator. We measure the temporal fluctuations in the average magnetization of a finite-size system of spin-1/2 particles. We experiment in a regime where the properties of the system are closely related to the integrable Hamiltonian with global spin-spin coupling, which enables analytical predictions for the long-time nonintegrable dynamics. The analytical expression for the temporal fluctuations predicts the exponential suppression of temporal fluctuations with increasing system size. Our measurement data is consistent with our theory predicting the regime of many-body dephasing.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.120605}, author = {Kaplan, Harvey B. and Guo, Lingzhen and Tan, Wen Lin and De, Arinjoy and Marquardt, Florian and Pagano, Guido and Monroe, Christopher} } @article {16686, title = {Many-Body Dynamical Localization in a Kicked Lieb-Liniger Gas}, journal = {Phys. Rev. Lett.}, volume = {124}, year = {2020}, month = {04/2020}, pages = {155302}, abstract = {The kicked rotor system is a textbook example of how classical and quantum dynamics can drastically differ. The energy of a classical particle confined to a ring and kicked periodically will increase linearly in time whereas in the quantum version the energy saturates after a finite number of kicks. The quantum system undergoes Anderson localization in angular-momentum space. Conventional wisdom says that in a many-particle system with short-range interactions the localization will be destroyed due to the coupling of widely separated momentum states. Here we provide evidence that for an interacting one-dimensional Bose gas, the Lieb-Liniger model, the dynamical localization can persist at least for an unexpectedly long time.

}, keywords = {Quantum Physics, Thermodynamics}, doi = {10.1103/PhysRevLett.124.155302}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.124.155302}, author = {Rylands, Colin and Rozenbaum, Efim B. and Galitski, Victor and Konik, Robert} } @article {19051, title = {Many-Body Level Statistics of Single-Particle Quantum Chaos}, journal = {Phys. Rev. Lett.}, volume = {125}, year = {2020}, month = {Dec}, pages = {250601}, doi = {10.1103/PhysRevLett.125.250601}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.125.250601}, author = {Liao, Yunxiang and Vikram, Amit and Galitski, Victor} } @article { ISI:000505981500001, title = {Many-body localization landscape}, journal = {Phys. Rev. B}, volume = {101}, number = {1}, year = {2020}, month = {JAN 6}, pages = {014201}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We generalize the notion of {\textquoteleft}{\textquoteleft}localization landscape,{{\textquoteright}{\textquoteright}} introduced by M. Filoche and S. Mayboroda {[}Proc. Natl. Acad. Sci. USA 109, 14761 (2012)] for the single-particle Schrodinger operator, to a wide class of interacting many-body Hamiltonians. The many-body localization landscape (MBLL) is defined on a graph in the Fock space, whose nodes represent the basis vectors in the Fock space and edges correspond to transitions between the nodes connected by the hopping term in the Hamiltonian. It is shown that in analogy to the single-particle case, the inverse MBLL plays the role of an effective potential in the Fock space. We construct a generalized discrete Agmon metric and prove Agmon inequalities on the Fock-state graph to obtain bounds on the exponential decay of the many-body wave functions in the Fock space. The corresponding construction is motivated by the semiclassical WKB approximation, but the bounds are exact and fully quantum mechanical. We then prove a series of locality theorems which establish where in the Fock space we expect eigenstates to localize. Using these results as well as the locator expansion, we establish evidence for the existence of many-body localized states for a wide class of lattice models in any physical dimension in at least a part of their Hilbert space. The key to this argument is the observation that in sharp contrast to the conventional locator expansion for the Green{\textquoteright}s function, the locator expansion for the landscape function contains no resonances. For short-range hopping, which limits the connectivity of the Fock-state graph, the locator series is proven to be convergent and bounded by a simple geometric series. This, in combination with the discrete Agmon-type inequalities and the locality theorems, shows that localization for a fraction of the Hilbert space survives weak interactions and weak hopping at least for some realizations of disorder, but cannot prove or rule out localization of the entire Hilbert space. We qualitatively discuss potential breakdown of the locator expansion in the MBLL for long-range hopping and the appearance of a mobility edge in higher-dimensional theories.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.014201}, author = {Balasubramanian, Shankar and Liao, Yunxiang and Galitski, Victor} } @article {16666, title = {Many-body topological invariants from randomized measurements in synthetic quantum matter}, journal = {Science Advances}, volume = {6}, year = {2020}, abstract = {Many-body topological invariants, as quantized highly nonlocal correlators of the many-body wave function, are at the heart of the theoretical description of many-body topological quantum phases, including symmetry-protected and symmetry-enriched topological phases. Here, we propose and analyze a universal toolbox of measurement protocols to reveal many-body topological invariants of phases with global symmetries, which can be implemented in state-of-the-art experiments with synthetic quantum systems, such as Rydberg atoms, trapped ions, and superconducting circuits. The protocol is based on extracting the many-body topological invariants from statistical correlations of randomized measurements, implemented with local random unitary operations followed by site-resolved projective measurements. We illustrate the technique and its application in the context of the complete classification of bosonic symmetry-protected topological phases in one dimension, considering in particular the extended Su-Schrieffer-Heeger spin model, as realized with Rydberg tweezer arrays.

}, doi = {10.1126/sciadv.aaz3666}, url = {https://advances.sciencemag.org/content/6/15/eaaz3666}, author = {Elben, Andreas and Yu, Jinlong and Zhu, Guanyu and Hafezi, Mohammad and Pollmann, Frank and Zoller, Peter and Vermersch, Beno\^{\i}t} } @article {clayburn_measurement_2020, title = {Measurement of the molecular dipole moment and the hyperfine and {Lambda}-doublet splittings of the {B}-3 {Pi}(1) state of thallium fluoride}, journal = {Phys. Rev. A}, volume = {102}, number = {5}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {nov}, abstract = {We report high-precision measurements on the thallium fluoride (J) over tilde = 1 hyperfine manifold of the B-3 Pi(1) (v = 0) state. This state is of special interest because it is central to an optical cycling scheme that is envisioned to play an important role in enhancing the sensitivity of the CeNTREX nuclear Schiff-moment experiment presently under construction. The measurements are made by monitoring the fluorescence induced by narrow-band laser excitation of a cryogenic molecular beam. We use a multipass arrangement of the laser beam to enhance fluorescence. When viewed with a camera, we can spatially resolve images from adjacent passes that approach the molecules from opposing directions. These images yield a sensitive visual method to identify the central frequency of a transition. Coupling these line-center determinations with frequency calibration from an acousto-optic modulator has allowed a more precise determination of the (J) over tilde = 1 manifold of hyperfine level splittings. We observe Stark shifts of the (J) over tilde = 1 levels and infer a permanent electric dipole moment of 2.28(7) D and Lambda-doublet splittings for the F-1{\textquoteright} = 1/2 and F-1{\textquoteright} = 3/2 manifolds of 14.4(9) and 17.4(11) MHz, respectively.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.102.052802}, author = {Clayburn, N. B. and Wright, T. H. and Norrgard, E. B. and DeMille, D. and Hunter, L. R.} } @conference {muller_measuring_2020, title = {Measuring the dark exciton in a quantum dot inside a planar microcavity using a bright state cycling transition}, booktitle = {Conference on Lasers and Electro-Optics (CLEO)}, series = {Conference on {Lasers} and {Electro}-{Optics}}, year = {2020}, note = {Backup Publisher: IEEE ISSN: 2160-9020 Type: Proceedings Paper}, publisher = {IEEE}, organization = {IEEE}, abstract = {We demonstrate the resonant excitation of a so-called dark exciton state in a quantum dot with a readout scheme based on the resonance fluorescence of the correlated bright exciton. (C) 2020 The Author(s)

}, isbn = {978-1-943580-76-7}, author = {Muller, Markus and Cao, Bin and Solomon, Glenn S.} } @article {wu_microwave{\textendash}optical_2020, title = {Microwave-to-{Optical} {Transduction} {Using} a {Mechanical} {Supermode} for {Coupling} {Piezoelectric} and {Optomechanical} {Resonators}}, journal = {Phys. Rev. Appl.}, volume = {13}, number = {1}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jan}, abstract = {The successes of superconducting quantum circuits at local manipulation of quantum information and photonics technology at long-distance transmission of the same have spurred interest in the development of quantum transducers for efficient, low-noise, and bidirectional frequency conversion of photons between the microwave and optical domains. We propose to realize such functionality through the coupling of electrical, piezoelectric, and optomechanical resonators. The coupling of the mechanical subsystems enables formation of a resonant mechanical supermode that provides a mechanically mediated, efficient single interface to both the microwave and optical domains. The conversion process is analyzed by applying an equivalent circuit model that relates device-level parameters to overall figures of merit for conversion efficiency eta and added noise N. These can be further enhanced by proper impedance matching of the transducer to an input microwave transmission line. The performance of potential transducers is assessed through finite-element simulations, with a focus on geometries in GaAs, followed by considerations of the AlN, LiNbO3, and AlN-on-Si platforms. We present strategies for maximizing eta and minimizing N, and find that simultaneously achieving eta {\textgreater} 50\% and N {\textless} 0.5 should be possible with current technology. We find that the use of a mechanical supermode for mediating transduction is a key enabler for high-efficiency operation, particularly when paired with an appropriate microwave impedance-matching network. Our comprehensive analysis of the full transduction chain enables us to outline a development path for the realization of high-performance quantum transducers that will constitute a valuable resource for quantum information science.

}, issn = {2331-7019}, doi = {10.1103/PhysRevApplied.13.014027}, author = {Wu, Marcelo and Zeuthen, Emil and Balram, Krishna Coimbatore and Srinivasan, Kartik} } @article { ISI:000571399800001, title = {Minimal Model for Fast Scrambling}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {13}, year = {2020}, month = {SEP 21}, pages = {130601}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study quantum information scrambling in spin models with both long-range all-to-all and shortrange interactions. WC argue that a simple global, spatially homogeneous interaction together with local chaotic dynamics is sufficient to give rise to fast scrambling, which describes the spread of quantum information over the entire system in a time that is logarithmic in the system size. This is illustrated in two tractable models: (1) a random circuit with Haar random local unitaties and a global interaction and (2) a classical model of globally coupled nonlinear oscillators. We use exact numerics to provide further evidence by studying the time evolution of an out-of-time-order correlator and entanglement entropy in spin chains of intermediate sizes. Our results pave the way towards experimental investigations of fast scrambling and aspects of quantum gravity with quantum simulators.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.130601}, author = {Belyansky, Ron and Bienias, Przemyslaw and Kharkov, Yaroslav A. and Gorshkov, V, Alexey and Swingle, Brian} } @article { ISI:000512770000004, title = {Mobility edge and intermediate phase in one-dimensional incommensurate lattice potentials}, journal = {Phys. Rev. B}, volume = {101}, number = {6}, year = {2020}, month = {FEB 11}, pages = {064203}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study theoretically the localization properties of two distinct one-dimensional quasiperiodic lattice models with a single-particle mobility edge (SPME) separating extended and localized states in the energy spectrum. The first one is the familiar Soukoulis-Economou trichromatic potential model with two incommensurate potentials, and the second is a system consisting of two coupled 1D Aubry-Andre chains each containing one incommensurate potential. We show that as a function of the Hamiltonian model parameters, both models have a wide single-particle intermediate phase, defined as the regime where localized and extended single-particle states coexist in the spectrum, leading to a behavior intermediate between purely extended or purely localized when the system is dynamically quenched from a generic initial state. Our results thus suggest that both systems could serve as interesting experimental platforms for studying the interplay between localized and extended states, and may provide insight into the role of the coupling of small baths to localized systems. We also calculate the Lyapunov (or localization) exponent for several incommensurate 1D models exhibiting SPME, finding that such localization critical exponents for quasiperiodic potential induced localization are nonuniversal and depend on the microscopic details of the Hamiltonian.

}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.064203}, author = {Li, Xiao and Das Sarma, Sankar} } @article { ISI:000523412800006, title = {Mobius Insulator and Higher-Order Topology in MnBi2nTe3n+1}, journal = {Phys. Rev. Lett.}, volume = {124}, number = {13}, year = {2020}, month = {APR 3}, pages = {136407}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We propose MnBi2nTe3n+1 as a magnetically tunable platform for realizing various symmetry-protected higher-order topology. Its canted antiferromagnetic phase can host exotic topological surface states with a Mobius twist that are protected by nonsymmorphic symmetry. Moreover, opposite surfaces hosting Mobius fermions are connected by one-dimensional chiral hinge modes, which offers the first material candidate of a higher-order topological Mobius insulator. We uncover a general mechanism to feasibly induce this exotic physics by applying a small in-plane magnetic field to the antiferromagnetic topological insulating phase of MnBi2nTe3n+1, as well as other proposed axion insulators. For other magnetic configurations, two classes of inversion-protected higher-order topological phases are ubiquitous in this system, which both manifest gapped surfaces and gapless chiral hinge modes. We systematically discuss their classification, microscopic mechanisms, and experimental signatures. Remarkably, the magnetic-field-induced transition between distinct chiral hinge mode configurations provides an effective {\textquoteleft}{\textquoteleft}topological magnetic switch{{\textquoteright}{\textquoteright}}.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.124.136407}, author = {Zhang, Rui-Xing and Wu, Fengcheng and Das Sarma, Sankar} } @article { ISI:000565086500001, title = {Multiterminal Josephson Effect}, journal = {Phys. Rev. X}, volume = {10}, number = {3}, year = {2020}, month = {SEP 2}, pages = {031051}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We report a probable observation of the dc Josephson effect in mesoscopic junctions of three and four superconductors. The devices are fabricated in a top-down fashion from a hybrid semiconductor-superconductor InAs/Al epitaxial heterostructure. In general, the critical current of an N-terminal junction is an (N - 1)-dimensional hypersurface in the space of bias currents, which can be reduced to a set of critical current contours. The geometry of critical current contours exhibits nontrivial responses to electrical gating, magnetic field, and phase bias, and it can be reproduced by the scattering formulation of the Josephson effect generalized to the case of N > 2. Besides establishing solid ground beneath a host of recent theory proposals, our experiment accomplishes an important step toward creating trijunctions of topological superconductors, essential for braiding operations.}, issn = {2160-3308}, doi = {10.1103/PhysRevX.10.031051}, author = {Pankratova, Natalia and Lee, Hanho and Kuzmin, Roman and Wickramasinghe, Kaushini and Mayer, William and Yuan, Joseph and Vavilov, Maxim G. and Shabani, Javad and Manucharyan, Vladimir E.} } @article { ISI:000575175400005, title = {Nature of the nonequilibrium phase transition in the non-Markovian driven Dicke model}, journal = {Phys. Rev. A}, volume = {102}, number = {3}, year = {2020}, month = {SEP 23}, pages = {032218}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The Dicke model famously exhibits a phase transition to a superradiant phase with a macroscopic population of photons and is realized in multiple settings in open quantum systems. In this paper, we study a variant of the Dicke model where the cavity mode is lossy due to the coupling to a Markovian environment while the atomic mode is coupled to a colored bath. We analytically investigate this model by inspecting its low-frequency behavior via the Schwinger-Keldysh field theory and carefully examine the nature of the corresponding superradiant phase transition. Integrating out the fast modes, we can identify a simple effective theory allowing us to derive analytical expressions for various critical exponents including the dynamical exponent. We find excellent agreement with previous numerical results when the non-Markovian bath is at zero temperature; however, contrary to these studies, our low-frequency approach reveals that the same exponents govern the critical behavior when the colored bath is at finite temperature unless the chemical potential is zero. Furthermore, we show that the superradiant phase transition is classical in nature, while it is genuinely nonequilibrium. We derive a fractional Langevin equation and conjecture the associated fractional Fokker-Planck equation that captures the system{\textquoteright}s long-time memory as well as its nonequilibrium behavior. Finally, we consider finite-size effects at the phase transition and identify the finite-size scaling exponents, unlocking a rich behavior in both statics and dynamics of the photonic and atomic observables.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.102.032218}, author = {Lundgren, Rex and Gorshkov, V, Alexey and Maghrebi, Mohammad F.} } @article {flebus_non-hermitian_2020, title = {Non-{Hermitian} topology of one-dimensional spin-torque oscillator arrays}, journal = {Phys. Rev. B}, volume = {102}, number = {18}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {nov}, abstract = {Magnetic systems have been extensively studied from both a fundamental physics perspective and as technological building blocks. The topological properties of magnonic excitations in these systems remain relatively unexplored, due to their inherently dissipative nature. The recent extension of the theory of topological classification to non-Hermitian Hamiltonians provides a pathway to engineer topological phases in dissipative systems. Here, we propose a magnonic realization of a topological, non-Hermitian system. A crucial ingredient of our proposal is the injection of spin current into the magnetic system, which alters and can even change the sign of terms describing dissipation. We show that the magnetic dynamics of an array of spin-torque oscillators can be mapped onto a non-Hermitian Su-Schrieffer-Heeger model exhibiting topologically protected edge states. The nontrivial topological phase is accessed by tuning the spin current injected into the array. We derive this result using both exact diagonalization of the effective non-Hermitian Hamiltonian and numerical analysis of the nonlinear equations of motion. In the nontrivial topological phase, a single spin-torque oscillator on the edge of the array is driven into auto-oscillation and emits a microwave signal, while the bulk oscillators remain inactive. Our findings have practical utility for memory devices and spintronics neural networks relying on spin-torque oscillators as constituent units.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.180408}, author = {Flebus, Benedetta and Duine, Rembert A. and Hurst, Hilary M.} } @article {sinha_non-markovian_2020, title = {Non-{Markovian} {Collective} {Emission} from {Macroscopically} {Separated} {Emitters}}, journal = {Phys. Rev. Lett.}, volume = {124}, number = {4}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jan}, abstract = {We study the collective radiative decay of a system of two two-level emitters coupled to a one-dimensional waveguide in a regime where their separation is comparable to the coherence length of a spontaneously emitted photon. The electromagnetic field propagating in the cavity-like geometry formed by the emitters exerts a retarded backaction on the system leading to strongly non-Markovian dynamics. The collective spontaneous emission rate of the emitters exhibits an enhancement or inhibition beyond the usual Dicke superradiance and subradiance due to self-consistent coherent time-delayed feedback.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.124.043603}, author = {Sinha, Kanupriya and Meystre, Pierre and Goldschmidt, Elizabeth A. and Fatemi, Fredrik K. and Rolston, S. L. and Solano, Pablo} } @inbook {rylands_nonequilibrium_2020, title = {Nonequilibrium {Aspects} of {Integrable} {Models}}, booktitle = {Annual Review of Condensed Matter Physics}, series = {Annual {Review} of {Condensed} {Matter} {Physics}}, volume = {11}, year = {2020}, note = {ISSN: 1947-5454 Journal Abbreviation: Annu. Rev. Condens. Matter Phys. Type: Review; Book Chapter}, pages = {147{\textendash}168}, publisher = {ANNUAL REVIEWS}, organization = {ANNUAL REVIEWS}, abstract = {Driven by breakthroughs in experimental and theoretical techniques, the study of nonequilibrium quantum physics is a rapidly expanding field with many exciting new developments. Among themanifold ways the topic can be investigated, one-dimensional systems provide a particularly fine platform. The trifecta of strongly correlated physics, powerful theoretical techniques, and experimental viability have resulted in a flurry of research activity over the past decade or so. In this review, we explore the nonequilibrium aspects of one-dimensional systems that are integrable. Through a number of illustrative examples, we discuss nonequilibrium phenomena that arise in such models, the role played by integrability, and the consequences these have for more generic systems.

}, keywords = {integrability, quantum work, quench dynamics, RG flow in time}, doi = {10.1146/annurev-conmatphys-031119-050630}, author = {Rylands, Colin and Andrei, Natan}, editor = {Marchetti, MC and Mackenzie, AP} } @article { ISI:000550580800001, title = {Nonequilibrium Criticality in Quench Dynamics of Long-Range Spin Models}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {4}, year = {2020}, month = {JUL 21}, pages = {040602}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Long-range interacting spin systems are ubiquitous in physics and exhibit a variety of ground-state disorder-to-order phase transitions. We consider a prototype of infinite-range interacting models known as the Lipkin-Meshkov-Glick model describing the collective interaction of N spins and investigate the dynamical properties of fluctuations and correlations after a sudden quench of the Hamiltonian. Specifically, we focus on critical quenches, where the initial state and/or the postquench Hamiltonian are critical. Depending on the type of quench, we identify three distinct behaviors where both the short-time dynamics and the stationary state at long times are effectively thermal, quantum, and genuinely nonequilibrium, characterized by distinct universality classes and static and dynamical critical exponents. These behaviors can be identified by an infrared effective temperature that is finite, zero, and infinite (the latter scaling with the system size as N-1/3), respectively. The quench dynamics is studied through a combination of exact numerics and analytical calculations utilizing the nonequilibrium Keldysh field theory. Our results are amenable to realization in experiments with trapped-ion experiments where long-range interactions naturally arise.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.040602}, author = {Titum, Paraj and Maghrebi, Mohammad F.} } @article { ISI:000515062100001, title = {Nonequilibrium Fixed Points of Coupled Ising Models}, journal = {Phys. Rev. X}, volume = {10}, number = {1}, year = {2020}, month = {FEB 19}, pages = {011039}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Driven-dissipative systems are expected to give rise to nonequilibrium phenomena that are absent in their equilibrium counterparts. However, phase transitions in these systems generically exhibit an effectively classical equilibrium behavior in spite of their nonequilibrium origin. In this paper, we show that multicritical points in such systems lead to a rich and genuinely nonequilibrium behavior. Specifically, we investigate a driven-dissipative model of interacting bosons that possesses two distinct phase transitions: one from a high- to a low-density phase-reminiscent of a liquid-gas transition-and another to an antiferromagnetic phase. Each phase transition is described by the Ising universality class characterized by an (emergent or microscopic) Z(2) symmetry. However, they coalesce at a multicritical point, giving rise to a nonequilibrium model of coupled Ising-like order parameters described by a Z(2) x Z(2) symmetry. Using a dynamical renormalization-group approach, we show that a pair of nonequilibrium fixed points (NEFPs) emerge that govern the long-distance critical behavior of the system. We elucidate various exotic features of these NEFPs. In particular, we show that a generic continuous scale invariance at criticality is reduced to a discrete scale invariance. This further results in complex-valued critical exponents and spiraling phase boundaries, and it is also accompanied by a complex Liouvillian gap even close to the phase transition. As direct evidence of the nonequilibrium nature of the NEFPs, we show that the fluctuation-dissipation relation is violated at all scales, leading to an effective temperature that becomes {\textquoteleft}{\textquoteleft}hotter{{\textquoteright}{\textquoteright}} and {\textquoteleft}{\textquoteleft}hotter{{\textquoteright}{\textquoteright}} at longer and longer wavelengths. Finally, we argue that this nonequilibrium behavior can be observed in cavity arrays with cross-Kerr nonlinearities.}, keywords = {Photonics, Quantum Physics, Statistical Physics}, issn = {2160-3308}, doi = {10.1103/PhysRevX.10.011039}, author = {Young, Jeremy T. and Gorshkov, Alexey V. and Foss-Feig, Michael and Maghrebi, Mohammad F.} } @article { ISI:000506845000012, title = {Nonequilibrium nature of nonlinear optical response: Application to the bulk photovoltaic effect}, journal = {Phys. Rev. B}, volume = {101}, number = {4}, year = {2020}, month = {JAN 13}, pages = {045201}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The bulk photovoltaic effect is an example of a nonlinear optical response that leads to a DC current that is relevant for photovoltaic applications. In this paper, we theoretically study this effect in the presence of electron-phonon interactions. Using the response function formalism, we find that the nonlinear optical response, in general, contains three operator correlation functions, one of which is not ordered in time. This latter correlator cannot be computed from equilibrium field theory. Using a semiclassical approach instead, we show that the bulk photovoltaic effect can be attributed to the dipole moment of the generated excitons. We then confirm the validity of the semiclassical result (which agrees with the noninteracting result) for nonlinear DC response from a quantum master equation approach. From this formalism we find that, in contrast to usual linear response, the scattering rate has a strong implicit effect on the nonlinear DC response. Most interestingly, the semiclassical treatment shows that the nonlinear DC response for spatially inhomogeneous excitation profiles is strongly nonlocal and must involve the aforementioned out-of-time-ordered correlators that cannot be computed by equilibrium field theory.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.045201}, author = {Barik, Tamoghna and Sau, Jay D.} } @article {hsiang_nonequilibrium_2020, title = {Nonequilibrium nonlinear open quantum systems: {Functional} perturbative analysis of a weakly anharmonic oscillator}, journal = {Phys. Rev. D}, volume = {101}, number = {12}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jun}, abstract = {We introduce a functional perturbative method for treating weakly nonlinear systems coupled with a quantum field bath. We demonstrate using this method to obtain the covariance matrix elements and the correlation functions of a quantum anharmonic oscillator interacting with a heat bath. We identify a fluctuation-dissipation relation based on the nonequilibrium dynamics of this nonlinear open quantum system. To establish its connection with dynamical equilibration, we further examine the energy flows between the anharmonic oscillator and the bath field. The vanishing of the net flow is an indication of the existence of an equilibrium state for such an open-system configuration. The results presented here are useful for studying the nonequilibrium physical processes of nonlinear quantum systems such as heat transfer or electron transport.}, issn = {1550-7998}, doi = {10.1103/PhysRevD.101.125002}, author = {Hsiang, Jen-Tsung and Hu, Bei-Lok} } @article {yang_nonequilibrium_2020, title = {Nonequilibrium steady state and heat transport in nonlinear open quantum systems: {Stochastic} influence action and functional perturbative analysis}, journal = {Ann. Phys.}, volume = {421}, year = {2020}, note = {Place: 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA Publisher: ACADEMIC PRESS INC ELSEVIER SCIENCE Type: Article}, month = {oct}, abstract = {In this paper, we show that a nonequilibrium steady state (NESS) exists at late times in open quantum systems with weak nonlinearity by following its nonequilibrium dynamics with a perturbative analysis. We consider an oscillator chain containing three-types of anharmonicity: cubic alpha- and quartic beta-type Fermi-Pasta-Ulam-Tsingou (FPUT) nearest-oscillator interactions and the on-site (pinned) Klein-Gordon (KG) quartic self-interaction. Assuming weak nonlinearity, we introduce a stochastic influence action approach to the problem and obtain the energy flows in different junctures across the chain. The formal results obtained here can be used for quantum transport problems in weakly nonlinear quantum systems. For alpha-type anharmonicity, we observe that the first-order corrections do not play any role in the thermal transport in the NESS of the configuration we considered. For KG and beta-types anharmonicity, we work out explicitly the case of two weakly nonlinearly coupled oscillators, with results scalable to any number of oscillators. We examine the late-time energy flows from one thermal bath to the other via the coupled oscillators, and show that both the zeroth- and the first-order contributions of the energy flows become constant in time at late times, signaling the existence of a late-time NESS to first order in nonlinearity. Our perturbative calculations provide a measure of the strength of nonlinearity for nonlinear open quantum systems, which may help control the mesoscopic heat transport distinct from or close to linear transport. Furthermore, our results also give a benchmark for the numerical challenge of simulating heat transport. Our setup and predictions can be implemented and verified by investigating heat flow in an array of Josephson junctions in the limit of large Josephson energy with the platform of circuit QED. (C) 2020 Elsevier Inc. All rights reserved.}, keywords = {Anharmonic chain, Feynman-Vernon influence functional, Functional perturbation, Nonequilibrium steady state, Open quantum systems, quantum transport}, issn = {0003-4916}, doi = {10.1016/j.aop.2020.168289}, author = {Yang, Jing and Hsiang, Jen-Tsung and Jordan, Andrew N. and Hu, B. L.} } @article {yoo_nonequilibrium_2020, title = {Nonequilibrium steady state phases of the interacting {Aubry}-{Andre}-{Harper} model}, journal = {Phys. Rev. B}, volume = {102}, number = {19}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {nov}, abstract = {Here, we study the phase diagram of the Aubry-Andre-Harper model in the presence of strong interactions as the strength of the quasiperiodic potential is varied. Previous work has established the existence of a many-body localized phase at a large potential strength; here, we find a rich phase diagram in the delocalized regime characterized by spin transport and unusual correlations. We calculate the nonequilibrium steady states of a boundary-driven strongly interacting Aubry-Andre-Harper model by employing the time-evolving block decimation algorithm on matrix product density operators. From these steady states, we extract spin transport as a function of system size and quasiperiodic potential strength. These data show spin transport going from superdiffusive to subdiffusive well before the localization transition; comparing to previous results, we also find that the transport transition is distinct from a transition observed in the speed of operator growth in the model. We also investigate the correlation structure of the steady state and find an unusual oscillation pattern for intermediate values of the potential strength. The unusual spin transport and quantum correlation structure suggest multiple dynamical phases between the much-studied thermal and many-body localized phases.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.195142}, author = {Yoo, Yongchan and Lee, Junhyun and Swingle, Brian} } @article {reiche_nonequilibrium_2020, title = {Nonequilibrium thermodynamics of quantum friction}, journal = {Phys. Rev. A}, volume = {102}, number = {5}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {nov}, abstract = {Thermodynamic principles are often deceptively simple and yet surprisingly powerful. We show how a simple rule, such as the net flow of energy in and out of a moving atom under a nonequilibrium steady state condition, can expose the shortcomings of many popular theories of quantum friction. Our thermodynamic approach provides a conceptual framework in guiding atom-optical experiments, thereby highlighting the importance of fluctuation-dissipation relations and long-time correlations between subsystems. Our results introduce consistency conditions for (numerical) models of nonequilibrium dynamics of open quantum systems.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.102.050203}, author = {Reiche, D. and Intravaia, F. and Hsiang, J-T and Busch, K. and Hu, B. L.} } @article { ISI:000510393100010, title = {Non-Markovian Collective Emission from Macroscopically Separated Emitters}, journal = {Phys. Rev. Lett.}, volume = {124}, number = {4}, year = {2020}, month = {JAN 31}, pages = {043603}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study the collective radiative decay of a system of two two-level emitters coupled to a one-dimensional waveguide in a regime where their separation is comparable to the coherence length of a spontaneously emitted photon. The electromagnetic field propagating in the cavity-like geometry formed by the emitters exerts a retarded backaction on the system leading to strongly non-Markovian dynamics. The collective spontaneous emission rate of the emitters exhibits an enhancement or inhibition beyond the usual Dicke superradiance and subradiance due to self-consistent coherent time-delayed feedback.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.124.043603}, author = {Sinha, Kanupriya and Meystre, Pierre and Goldschmidt, Elizabeth A. and Fatemi, Fredrik K. and Rolston, S. L. and Solano, Pablo} } @article { ISI:000517213700002, title = {Nonmonotonic plasmon dispersion in strongly interacting Coulomb Luttinger liquids}, journal = {Phys. Rev. B}, volume = {101}, number = {7}, year = {2020}, month = {FEB 27}, pages = {075430}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We demonstrate that the plasmon in one-dimensional Coulomb interacting electron fluids can develop a finite-momentum maxon-roton-like nonmonotonic energy-momentum dispersion. Such an unusual nonmonotonicity arises from the strongly interacting 1/r Coulomb potential going beyond the conventional band linearization approximation used in the standard bosonization theories of Luttinger liquids. We provide details for the nonmonotonic plasmon dispersion using both bosonization and random-phase approximation theories. We also calculate the specific heat including the nonmonotonicity and discuss possibilities for observing the nonmonotonic plasmon dispersion in various physical systems, including semiconductor quantum wires, carbon nanotubes, and the twisted bilayer graphene at subdegree twist angles, which naturally realize one-dimensional domain-wall states. We provide results for several different models of long-range interaction showing that the nonomonotonic charge collective mode dispersion is a generic phenomenon in one-dimensional strongly interacting electron systems.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.075430}, author = {Chou, Yang-Zhi and Das Sarma, Sankar} } @article {hao_nuclear_2020, title = {Nuclear spin-dependent parity-violating effects in light polyatomic molecules}, journal = {Phys. Rev. A}, volume = {102}, number = {5}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {nov}, abstract = {Measurements of nuclear spin-dependent parity-violating (NSD-PV) effects provide an excellent opportunity to test nuclear models and to search for physics beyond the Standard Model. Molecules possess closely spaced states with opposite parity which may be easily tuned to degeneracy to greatly enhance the observed parity-violating effects. A high-sensitivity measurement of NSD-PV effects using light triatomic molecules is in preparation [E. B. Norrgard et al., Common. Phys. 2, 77 (2019)]. Importantly, by comparing these measurements in light nuclei with prior and ongoing measurements in heavier systems, the contribution to NSD-PV from Z(0)-boson exchange between the electrons and the nuclei may be separated from the contribution of the nuclear anapole moment. Furthermore, light triatomic molecules offer the possibility to search for new particles, such as the postulated Z{\textquoteright} boson. In this work, we detail a sensitive measurement scheme and present high-accuracy molecular and nuclear calculations needed for interpretation of NSD-PV experiments on triatomic molecules composed of light elements, Be, Mg, N, and C. The ab initio nuclear structure calculations, performed within the no-core shell model provide a reliable prediction of the magnitude of different contributions to the NSD-PV effects in the four nuclei. These results differ significantly from the predictions of the standard single-particle model and highlight the importance of including many-body effects in such calculations. In order to extract the NSD-PV contributions from measurements, a parity-violating interaction parameter W-PV, which depends on the molecular structure, needs to be known with a high accuracy. We have calculated these parameters for the triatomic molecules of interest using the relativistic coupled-cluster approach. In order to facilitate the interpretation of future experiments we provide uncertainties on the calculated parameters. A scheme for measurement using laser-cooled polyatomic molecules in a molecular fountain is presented, along with an estimate of the expected sensitivity of such an experiment. This experimental scheme, combined with the presented state-of-the-art calculations, opens exciting prospects for a measurement of the anapole moment and the PV effects due to the electron-nucleon interactions with unprecedented accuracy and for a new path towards detection of signatures of physics beyond the Standard Model.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.102.052828}, author = {Hao, Yongliang and Navratil, Petr and Norrgard, Eric B. and Ilias, Miroslav and Eliav, Ephraim and Timmermans, Rob G. E. and Flambaum, Victor V. and Borschevsky, Anastasia} } @article { ISI:000524978500001, title = {Number-Theoretic Characterizations of Some Restricted Clifford}, journal = {Quantum}, volume = {4}, year = {2020}, month = {APR 3}, publisher = {VEREIN FORDERUNG OPEN ACCESS PUBLIZIERENS QUANTENWISSENSCHAF}, type = {Article}, abstract = {Kliuchnikov, Maslov, and Mosca proved in 2012 that a 2 x 2 unitary matrix V can be exactly represented by a single-qubit Clifford + T circuit if and only if the entries of V belong to the ring Z{[}1/root 2, i]. Later that year, Giles and Selinger showed that the same restriction applies to matrices that can be exactly represented by a multi-qubit Clifford + T circuit. These number-theoretic characterizations shed new light upon the structure of Clifford + T circuits and led to remarkable developments in the field of quantum compiling. In the present paper, we provide number-theoretic characterizations for certain restricted Clifford + T circuits by considering unitary matrices over subrings of Z{[}1/root 2, i]. We focus on the subrings Z{[}1./2], Z{[}1/root 2], Z{[}1/i root 2], and Z{[}1/2, i], and we prove that unitary matrices with entries in these rings correspond to circuits over well-known universal gate sets. In each case, the desired gate set is obtained by extending the set of classical reversible gates \{X, CX, CCX\} with an analogue of the Hadarnard gate and an optional phase gate.}, issn = {2521-327X}, author = {Amy, Matthew and Glaudell, Andrew N. and Ross, Neil J.} } @article {xie_observation_2020, title = {Observation of {Efimov} {Universality} across a {Nonuniversal} {Feshbach} {Resonance} in {K}-39}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {24}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {dec}, abstract = {We study three-atom inelastic scattering in ultracold K-39 near a Feshbach resonance of intermediate coupling strength. The nonuniversal character of such resonance leads to an abnormally large Efimov absolute length scale and a relatively small effective range r(e), allowing the features of the 39 K Efimov spectrum to be better isolated from the short-range physics. Meticulous characterization of and correction for finite-temperature effects ensure high accuracy on the measurements of these features at large-magnitude scattering lengths. For a single Feshbach resonance, we unambiguously locate four distinct features in the Efimov structure. Three of these features form ratios that obey the Efimov universal scaling to within 10\%, while the fourth feature, occurring at a value of scattering length closest to r(e), instead deviates from the universal value.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.243401}, author = {Xie, Xin and Van de Graaff, Michael J. and Chapurin, Roman and Frye, Matthew D. and Hutson, Jeremy M. and D{\textquoteright}Incao, Jose P. and Julienne, Paul S. and Ye, Jun and Cornell, Eric A.} } @article {lu_-chip_2020, title = {On-chip optical parametric oscillation into the visible: generating red, orange, yellow, and green from a near-infrared pump}, journal = {Optica}, volume = {7}, number = {10}, year = {2020}, note = {Place: 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA Publisher: OPTICAL SOC AMER Type: Article}, month = {oct}, pages = {1417{\textendash}1425}, abstract = {The on-chip generation of coherent, single-frequency laser light that can be tuned across the visible spectrum would help enable a variety of applications in spectroscopy, metrology, and quantum science. Recently, third-order optical parametric oscillation (OPO) in a microresonator has shown great promise as an efficient and scalable approach toward this end. However, considering visible light generation, so far only red light at {\textless}420 THz (near the edge of the visible band) has been reported. In this work, we overcome strong material dispersion at visible wavelengths and demonstrate on-chip OPO in a Si3N4 microresonator covering {\textgreater}130 THz of the visible spectrum, including red, orange, yellow, and green wavelengths. In particular, using an input pump laser that is scanned 5 THz in the near-infrared from 386 THz to 391 THz, the OPO output signal is tuned from the near-infrared at 395 THz to the visible at 528 THz, while the OPO output idler is tuned from the near-infrared at 378 THz to the infrared at 254 THz. The widest signal-idler separation of 274 THz is more than an octave in span and is the widest demonstrated for a nanophotonic OPO to date. More generally, our work shows how nonlinear nanophotonics can transform light from readily accessible compact near-infrared lasers to targeted visible wavelengths of interest. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {2334-2536}, doi = {10.1364/OPTICA.393810}, author = {Lu, Xiyuan and Moille, Gregory and Rao, Ashutosh and Westly, Daron A. and Srinivasan, Kartik} } @article { ISI:000550690300003, title = {On-demand indistinguishable single photons from an efficient and pure source based on a Rydberg ensemble}, journal = {Optica}, volume = {7}, number = {7}, year = {2020}, month = {JUL 20}, pages = {813-819}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {Single photons coupled to atomic systems have shown to be a promising platform for developing quantum technologies. Yet a bright on-demand, highly pure, and highly indistinguishable single-photon source compatible with atomic platforms is lacking. In this work, we demonstrate such a source based on a strongly interacting Rydberg system. The large optical nonlinearities in a blockaded Rydberg ensemble convert coherent light into a single collective excitation that can be coherently retrieved as a quantum field. We simultaneously observe a fully single-mode (spectral, temporal, spatial, and polarization) efficiency up to 0.098(2), a detector-background-subtracted g((2))+5.0(1.6) x 10(-4), and indistinguishability of 0.980(7), at an average photon production rate of 1.18(2) x 10(4) s(-1), All of these make this system promising for scalable quantum information applications. Furthermore, we investigate the effects of contaminant Rydberg excitations on the source efficiency and observed single-mode efficiencies up to 0.18(2) for lower photon rates. Finally, recognizing that many quantum information protocols require a single photon in a fully single mode, we introduce metrics that take into account all degrees of freedom to benchmark the performance of on-demand sources. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {2334-2536}, doi = {10.1364/OPTICA.391485}, author = {Ornelas-Huerta, D. P. and Craddock, A. N. and Goldschmidt, E. A. and Hachtel, A. J. and Wang, Y. and Bienias, P. and Gorshkov, A. V. and Rolston, S. L. and Porto, J. V.} } @article { ISI:000519701600004, title = {One-dimensional few-electron effective Wigner crystal in quantum and classical regimes}, journal = {Phys. Rev. B}, volume = {101}, number = {12}, year = {2020}, month = {MAR 16}, pages = {125113}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {A system of confined charged electrons interacting via the long-range Coulomb force can form a Wigner crystal due to their mutual repulsion. This happens when the potential energy of the system dominates over its kinetic energy, i.e., at low temperatures for a classical system and at low densities for a quantum one. At T = 0, the system is governed by quantum mechanics, and hence the spatial density peaks associated with crystalline charge localization are sharpened for a lower average density. Conversely, in the classical limit of high temperatures, the crystalline spatial density peaks are suppressed (recovered) at a lower (higher) average density. In this paper, we study those two limits separately using an exact diagonalization of small one-dimensional (1D) systems containing few (\<10) electrons and propose an approximate method to connect them into a unified effective phase diagram for Wigner few-electron crystallization. The result is a qualitative quantum-classical crossover phase diagram of an effective 1D Wigner crystal. We show that although such a 1D system is at best an effective crystal with no true long-range order (and thus no real phase transition), the spatial density peaks associated with the quasicrystallization should be experimentally observable in a few-electron 1D system. We find that the effective crystalline structure slowly disappears with both the crossover average density and crossover temperature for crystallization decreasing with increasing particle number, consistent with the absence of any true long-range 1D order. Thus, an effective few-electron 1D Wigner crystal may be construed either as existing at all densities (manifesting short-range order) or as nonexisting at all densities (not manifesting any long-range order). Within one unified description, we show through exact theoretical calculations how a small 1D system interacting through the long-range Coulomb interaction could manifest effective Wigner solid behavior both in classical and quantum regimes. In fact, one peculiar aspect of the effective finite-size nature of 1D Wigner crystallization we find is that even a short-range interaction would lead to a finite-size 1D crystal, except that the crystalline order vanishes much faster with increasing system size in the short-range interacting system compared with the long-range interacting one.

}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.125113}, author = {DinhDuy Vu and Das Sarma, Sankar} } @article {ge_operational_2020, title = {Operational resource theory of nonclassicality via quantum metrology}, journal = {Phys. Rev. Res.}, volume = {2}, number = {2}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, abstract = {The nonclassical properties of quantum states are of tremendous interest due to their potential applications in future technologies. It has recently been realized that the concept of a resource theory is a powerful approach to quantifying and understanding nonclassicality. To realize the potential of this approach, one must first find resource theoretic measures of nonclassicality that are operational, meaning that they also quantify the ability of quantum states to provide enhanced performance for specific tasks, such as precision sensing. Here we achieve a significant milestone in this endeavor by presenting such an operational resource theoretic measure. In addition to satisfying the requirements of a resource measure, it has the closest possible relationship to the quantum enhancement provided by a nonclassical state for measuring phase-space displacement: It is equal to this enhancement for pure states and has a tight upper bound on it for mixed states. We also show that a lower bound on this measure can be obtained experimentally using a simple Mach-Zehnder interferometer.}, doi = {10.1103/PhysRevResearch.2.023400}, author = {Ge, Wenchao and Jacobs, Kurt and Asiri, Saeed and Foss-Feig, Michael and Zubairy, M. Suhail} } @article { ISI:000530031700002, title = {Operator Levy Flight: Light Cones in Chaotic Long-Range Interacting Systems}, journal = {Phys. Rev. Lett.}, volume = {124}, number = {18}, year = {2020}, month = {MAY 4}, pages = {180601}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We argue that chaotic power-law interacting systems have emergent limits on information propagation, analogous to relativistic light cones, which depend on the spatial dimension d and the exponent a governing the decay of interactions. Using the dephasing nature of quantum chaos, we map the problem to a stochastic model with a known phase diagram. A linear light cone results for alpha >= d + 1/2. We also provide a Levy flight (long-range random walk) interpretation of the results and show consistent numerical data for 1D long-range spin models with 200 sites.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.124.180601}, author = {Zhou, Tianci and Xu, Shenglong and Chen, Xiao and Guo, Andrew and Swingle, Brian} } @article { ISI:000548284200010, title = {Optical clocks based on the Cf15+ and Cf17+ ions}, journal = {Phys. Rev. A}, volume = {102}, number = {1}, year = {2020}, month = {JUL 6}, pages = {012802}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Recent experimental progress in cooling, trapping, and quantum logic spectroscopy of highly charged ions (HCIs) made HCIs accessible for high-resolution spectroscopy and precision fundamental studies. Based on these achievements, we explore a possibility to develop optical clocks using transitions between the ground and a low-lying excited state in Cf15+ and Cf17+ ions. Using a high-accuracy relativistic method of calculation, we predicted the wavelengths of clock transitions, calculated relevant atomic properties, and analyzed a number of systematic effects (such as the electric quadrupole, micromotion, and quadratic Zeeman shifts of the clock transitions) that affect the accuracy and stability of the optical clocks. We also calculated magnetic dipole hyperfine-structure constants of the clock states and the blackbody radiation shifts of the clock transitions.}, issn = {1050-2947}, doi = {10.1103/PhysRevA.102.012802}, author = {Porsev, S. G. and Safronova, I, U. and Safronova, M. S. and Schmidt, P. O. and Bondarev, I, A. and Kozlov, M. G. and Tupitsyn, I. I. and Cheung, C.} } @article { ISI:000538714300009, title = {Optical enhancement of superconductivity via targeted destruction of charge density waves}, journal = {Phys. Rev. B}, volume = {101}, number = {22}, year = {2020}, month = {JUN 8}, pages = {224506}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {It has been experimentally established that the occurrence of charge density waves is a common feature of various underdoped cuprate superconducting compounds. The observed states, which are often found in the form of bond density waves (BDWs), usually occur in a temperature regime immediately above the superconducting transition temperature. Motivated by recent optical experiments on superconducting materials, where it has been shown that optical irradiation can transiently improve the superconducting features, here we propose an approach for the enhancement of superconductivity by the targeted destruction of the BDW order which we expect to be more efficient than the previous methods. Since BDW states are usually found in competition with superconductivity, suppression of the BDW order enhances the tendency of electrons to form Cooper pairs after reaching a steady state. By investigating the optical coupling of gapless, collective fluctuations of the BDW modes, we argue that the resonant excitation of these modes can melt the underlying BDW order parameter. We propose an experimental setup to implement such an optical coupling using two-dimensional plasmon-polariton hybrid systems.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.224506}, author = {Dehghani, Hossein and Raines, Zachary M. and Galitski, Victor M. and Hafezi, Mohammad} } @article { ISI:000527498000001, title = {Optical excitations in compressible and incompressible two-dimensional electron liquids}, journal = {Phys. Rev. B}, volume = {101}, number = {15}, year = {2020}, month = {APR 22}, pages = {155127}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Optically generated electron-hole pairs can probe strongly correlated electronic matter, or, by forming exciton-polaritons within an optical cavity, give rise to photonic nonlinearities. The present paper theoretically studies the properties of electron-hole pairs in a two-dimensional electron liquid in the fractional quantum Hall regime. In particular, we quantify the effective interactions between optical excitations by numerically evaluating the system{\textquoteright}s energy spectrum under the assumption of full spin and Landau level polarization. Optically most active are those pair excitations which do not modify the correlations of the electron liquid, also known as multiplicative states. In the case of spatial separation of electrons and holes, these excitations interact repulsively with each other. However, when the electron liquid is compressible, other nonmultiplicative configurations occur at lower energies. The interactions of such dark excitations strongly depend on the liquid, and can also become attractive. For the case of a single excitation, we also study the effect of Landau level mixing in the valence band which can dramatically change the effective mass of an exciton.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.155127}, author = {Grass, Tobias and Cotlet, Ovidiu and Imamoglu, Atac and Hafezi, Mohammad} } @article {kim_optical_2020, title = {Optical imprinting of superlattices in two-dimensional materials}, journal = {Phys. Rev. Res.}, volume = {2}, number = {4}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {oct}, abstract = {We propose an optical method of shining circularly polarized and spatially periodic laser fields to imprint superlattice structures in two-dimensional electronic systems. By changing the configuration of the optical field, we synthesize various lattice structures with different spatial symmetry, periodicity, and strength. We find that the wide optical tunability allows one to tune different properties of the effective band structure, including Chern number, energy bandwidths, and band gaps. The in situ tunability of the superlattice gives rise to unique physics ranging from the topological transitions to the creation of the flat bands through the kagome superlattice, which can allow a realization of strongly correlated phenomena in Floquet systems. We consider the high-frequency regime where the electronic system can remain in the quasiequilibrium phase for an extended amount of time. The spatiotemporal reconfigurability of the present scheme opens up possibilities to control light-matter interaction to generate novel electronic states and optoelectronic devices.}, doi = {10.1103/PhysRevResearch.2.043004}, author = {Kim, Hwanmun and Dehghani, Hossein and Aoki, Hideo and Martin, Ivar and Hafezi, Mohammad} } @article { ISI:000542514200007, title = {Phonon scattering induced carrier resistivity in twisted double-bilayer graphene}, journal = {Phys. Rev. B}, volume = {101}, number = {24}, year = {2020}, month = {JUN 24}, pages = {245436}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {In this work we carry out a theoretical study of the phonon-induced resistivity in twisted double bilayer graphene (TDBG), in which two Bernal-stacked bilayer graphene devices are rotated relative to each other by a small angle theta. We show that at small twist angles (theta similar to 1 degrees) the effective mass of the TDBG system is greatly enhanced, leading to a drastically increased phonon-induced resistivity in the high-temperature limit where phonon scattering leads to a linearly increasing resistivity with increasing temperature. We also discuss possible implications of our theory on superconductivity in such a system and provide an order of magnitude estimation of the superconducting transition temperature.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.245436}, author = {Li, Xiao and Wu, Fengcheng and Das Sarma, S.} } @article {rylands_photon-mediated_2020, title = {Photon-{Mediated} {Peierls} {Transition} of a {1D} {Gas} in a {Multimode} {Optical} {Cavity}}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {1}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {jul}, abstract = {The Peierls instability toward a charge density wave is a canonical example of phonon-driven strongly correlated physics and is intimately related to topological quantum matter and exotic superconductivity. We propose a method for realizing an analogous photon-mediated Peierls transition, using a system of one-dimensional tubes of interacting Bose or Fermi atoms trapped inside a multimode confocal cavity. Pumping the cavity transversely engineers a cavity-mediated metal-to-insulator transition in the atomic system. For strongly interacting bosons in the Tonks-Girardeau limit, this transition can be understood (through fermionization) as being the Peierls instability. We extend the calculation to finite values of the interaction strength and derive analytic expressions for both the cavity field and mass gap. They display nontrivial power law dependence on the dimensionless matter-light coupling.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.010404}, author = {Rylands, Colin and Guo, Yudan and Lev, Benjamin L. and Keeling, Jonathan and Galitski, Victor} } @article {16931, title = {Photon propagation through dissipative Rydberg media at large input rates}, journal = {Phys. Rev. Research}, volume = {2}, year = {2020}, month = {Jul}, pages = {033049}, abstract = {We study the dissipative propagation of quantized light in interacting Rydberg media under the conditions of electromagnetically induced transparency. Rydberg blockade physics in optically dense atomic media leads to strong dissipative interactions between single photons. The regime of high incoming photon flux constitutes a challenging many-body dissipative problem. We experimentally study in detail the pulse shapes and the second-order correlation function of the outgoing field and compare our data with simulations based on two novel theoretical approaches well-suited to treat this many-photon limit. At low incoming flux, we report good agreement between both theories and the experiment. For higher input flux, the intensity of the outgoing light is lower than that obtained from theoretical predictions. We explain this discrepancy using a simple phenomenological model taking into account pollutants, which are nearly stationary Rydberg excitations coming from the reabsorption of scattered probe photons. At high incoming photon rates, the blockade physics results in unconventional shapes of measured correlation functions.

}, keywords = {Models, Photonics}, doi = {10.1103/PhysRevResearch.2.033049}, url = {https://link.aps.org/doi/10.1103/PhysRevResearch.2.033049}, author = {Bienias, Przemyslaw and Douglas, James and Paris-Mandoki, Asaf and Titum, Paraj and Mirgorodskiy, Ivan and Tresp, Christoph and Zeuthen, Emil and Gullans, Michael J. and Manzoni, Marco and Hofferberth, Sebastian and Chang, Darrick and Gorshkov, Alexey V.} } @article { ISI:000517742600004, title = {Photonic materials in circuit quantum electrodynamics}, journal = {Nat. Phys.}, volume = {16}, number = {3}, year = {2020}, month = {MAR}, pages = {268-279}, publisher = {NATURE PUBLISHING GROUP}, type = {Review}, abstract = {Photonic synthetic materials provide an opportunity to explore the role of microscopic quantum phenomena in determining macroscopic material properties. There are, however, fundamental obstacles to overcome - in vacuum, photons not only lack mass, but also do not naturally interact with one another. Here, we review how the superconducting quantum circuit platform has been harnessed in the last decade to make some of the first materials from light. We describe the structures that are used to imbue individual microwave photons with matter-like properties such as mass, the nonlinear elements that mediate interactions between these photons, and quantum dynamic/thermodynamic approaches that can be used to assemble and stabilize strongly correlated states of many photons. We then describe state-of-the-art techniques to generate synthetic magnetic fields, engineer topological and non-topological flat bands and explore the physics of quantum materials in non-Euclidean geometries - directions that we view as some of the most exciting for this burgeoning field. Finally, we discuss upcoming prospects, and in particular opportunities to probe novel aspects of quantum thermalization and detect quasi-particles with exotic anyonic statistics, as well as potential applications in quantum information science. This Review Article surveys the physics of many-body quantum states formed by microwave photons in circuit quantum electrodynamics environments.}, issn = {1745-2473}, doi = {10.1038/s41567-020-0815-y}, author = {Carusotto, Iacopo and Houck, Andrew A. and Kollar, Alicia J. and Roushan, Pedram and Schuster, David I. and Simon, Jonathan} } @article {16911, title = {Photon-Mediated Peierls Transition of a 1D Gas in a Multimode Optical Cavity}, journal = {Phys. Rev. Lett.}, volume = {125}, year = {2020}, month = {Jul}, pages = {010404}, abstract = {The Peierls instability toward a charge density wave is a canonical example of phonon-driven strongly correlated physics and is intimately related to topological quantum matter and exotic superconductivity. We propose a method for realizing an analogous photon-mediated Peierls transition, using a system of one-dimensional tubes of interacting Bose or Fermi atoms trapped inside a multimode confocal cavity. Pumping the cavity transversely engineers a cavity-mediated metal-to-insulator transition in the atomic system. For strongly interacting bosons in the Tonks-Girardeau limit, this transition can be understood (through fermionization) as being the Peierls instability. We extend the calculation to finite values of the interaction strength and derive analytic expressions for both the cavity field and mass gap. They display nontrivial power law dependence on the dimensionless matter-light coupling.

}, doi = {10.1103/PhysRevLett.125.010404}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.125.010404}, author = {Rylands, Colin and Guo, Yudan and Lev, Benjamin L. and Keeling, Jonathan and Galitski, Victor} } @article {pan_physical_2020, title = {Physical mechanisms for zero-bias conductance peaks in {Majorana} nanowires}, journal = {Phys. Rev. Res.}, volume = {2}, number = {1}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {mar}, abstract = {Motivated by the need to understand and simulate the ubiquitous experimentally observed zero-bias conductance peaks in superconductor-semiconductor hybrid structures, we theoretically investigate the tunneling conductance spectra in one-dimensional nanowires in proximity to superconductors in a systematic manner taking into account several different physical mechanisms producing zero-bias conductance peaks. The mechanisms we consider are the presence of quantum dots, inhomogeneous potential, random disorder in the chemical potential, random fluctuations in the superconducting gap, and in the effective g factor with the self-energy renormalization induced by the parent superconductor in both short (L similar to 1 mu m) and long nanowires (L similar to 3 mu m). We classify all foregoing theoretical results for zero-bias conductance peaks into three types: the good, the bad, and the ugly, according to the physical mechanisms producing the zero-bias peaks and their topological properties. We find that, although the topological Majorana zero modes are immune to weak disorder, strong disorder ({\textquotedblright}ugly{\textquotedblright}) completely suppresses topological superconductivity and generically leads to trivial zero-bias peaks. Compared qualitatively with the extensive existing experimental results in the superconductor-semiconductor nanowire structures, we conclude that most current experiments are likely exploring trivial zero-bias peaks in the {\textquotedblleft}ugly{\textquotedblright} situation dominated by strong disorder. We also study the nonlocal end-to-end correlation measurement in both the short and long wires, and point out the limitation of the nonlocal correlation in ascertaining topological properties particularly when applied to short wires. Although we present results for {\textquotedblleft}good{\textquotedblright} and {\textquotedblleft}bad{\textquotedblright} zero-bias peaks, arising respectively from topological Majorana bound states and trivial Andreev bound states, strictly for the sake of direct comparison with the {\textquotedblleft}ugly{\textquotedblright} zero-bias conductance peaks arising from strong disorder, the main goal of the current work is to establish with a very high confidence level the real physical possibility that essentially all experimentally observed zero-bias peaks in Majorana nanowires are most likely ugly, i.e., purely induced by strong disorder, and are as such utterly nontopological. Our work clearly suggests that an essential prerequisite for any future observation of topological Majorana zero modes in nanowires is a substantialmaterials improvement of the semiconductor-superconductor hybrid systems leading to much cleaner wires.}, doi = {10.1103/PhysRevResearch.2.013377}, author = {Pan, Haining and Das Sarma, S.} } @conference {moille_post-processing_2020, title = {Post-{Processing} {Dispersion} {Engineering} of {Frequency} {Combs} {In} {Microresonator} {Addressing} {Atomic} {Clock}}, booktitle = {Conference on Lasers and Electro-Optics (CLEO)}, series = {Conference on {Lasers} and {Electro}-{Optics}}, year = {2020}, note = {Backup Publisher: IEEE ISSN: 2160-9020 Type: Proceedings Paper}, publisher = {IEEE}, organization = {IEEE}, abstract = {We study Si3N4 microresonator frequency comb to address atomic transition in the visible. We show that thanks to our air-clad system, post-process dispersion engineering through trimming allows precise control of the dispersive wave position. (C) 2020 The Author(s)

}, isbn = {978-1-943580-76-7}, author = {Moille, Gregory and Lu, Xiyuan and Rao, Ashutosh and Weedy, Daron and Srinivasan, Kartik} } @article { ISI:000555932400003, title = {Probing the relaxed relaxion at the luminosity and precision frontiers}, journal = {J. High Energy Phys.}, number = {7}, year = {2020}, month = {JUL 22}, pages = {153}, publisher = {SPRINGER}, type = {Article}, abstract = {Cosmological relaxation of the electroweak scale is an attractive scenario relaxion, is a light spin-zero field which dynamically relaxes the Higgs mass with respect to its natural large value. We show that the relaxion is generically stabilized at a special position in the field space, which leads to suppression of its mass and potentially unnatural values for the model{\textquoteright}s effective low-energy couplings. In particular, we find that the relaxion mixing with the Higgs can be several orders of magnitude above its naive naturalness bound. Low energy observers may thus find the relaxion theory being fine-tuned although the relaxion scenario itself is constructed in a technically natural way. More generally, we identify the lower and upper bounds on the mixing angle. We examine the experimental implications of the above observations at the luminosity and precision frontiers. A particular attention is given to the impressive ability of future nuclear clocks to search for rapidly oscillating scalar ultra-light dark matter, where the future projected sensitivity is presented.}, keywords = {Beyond Standard Model, Cosmology of Theories beyond the SM}, issn = {1029-8479}, doi = {10.1007/JHEP07(2020)153}, author = {Banerjee, Abhishek and Kim, Hyungjin and Matsedonskyi, Oleksii and Perez, Gilad and Safronova, Marianna S.} } @article { ISI:000567752300004, title = {Probing XY phase transitions in a Josephson junction array with tunable frustration}, journal = {Phys. Rev. B}, volume = {102}, number = {9}, year = {2020}, month = {SEP 10}, pages = {094509}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The seminal theoretical works of Berezinskii, Kosterlitz, and Thouless presented a paradigm for phase transitions in condensed matter that are driven by topological excitations. These transitions have been extensively studied in the context of two-dimensional XY models-coupled compasses-and have generated interest in the context of quantum simulation. Here, we use a circuit quantum-electrodynamics architecture to study the critical behavior of engineered XY models through their dynamical response. In particular, we examine not only the unfrustrated case but also the fully frustrated case which leads to enhanced degeneracy associated with the spin rotational {[}U(1)] and discrete chiral (Z(2)) symmetries. The nature of the transition in the frustrated case has posed a challenge for theoretical studies while direct experimental probes remain elusive. Here we identify the transition temperatures for both the unfrustrated and fully frustrated XY models by probing a Josephson junction array close to equilibrium using weak microwave excitations and measuring the temperature dependence of the effective damping obtained from the complex reflection coefficient. We argue that our probing technique is primarily sensitive to the dynamics of the U(1) part.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.094509}, author = {Cosmic, R. and Kawabata, K. and Ashida, Y. and Ikegami, H. and Furukawa, S. and Patil, P. and Taylor, J. M. and Nakamura, Y.} } @article {eller_producing_2020, title = {Producing flow in racetrack atom circuits by stirring}, journal = {Phys. Rev. A}, volume = {102}, number = {6}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {dec}, abstract = {We present a study of how macroscopic flow can be produced in Bose-Einstein condensates confined in a {\textquotedblleft}racetrack{\textquotedblright} potential by stirring with a wide rectangular barrier. This potential consists of two half-circle channels separated by straight channels of length L and reduces to a ring potential if L = 0. We present the results of a flow-production study where racetrack condensates were stirred with a barrier under varying conditions of barrier height, stir speed, racetrack geometry, and temperature. The result was that stirring was readily able to produce flow in ring and nonring geometries but that the exact amount of flow produced depended on all of the study parameters. We therefore investigated the mechanism by which flow was produced in the stirring process. The basic mechanism that we discovered was that when the sweeping barrier potential height reached a critical value a series of phase slip (i.e., a sudden change in the phase winding around the condensate midtrack) events occurred. Phase slipping stopped when the flow produced overtook the speed of the stirring barrier. Disturbances generated at each phase slip circulated around the channel and served to convert the initially localized velocity distribution into smooth macroscopic flow. This picture of the mechanism for making flow should facilitate the design of closed-channel atom circuits for creating a desired amount of quantized smooth flow on demand.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.102.063324}, author = {Eller, Benjamin and Oladehin, Olatunde and Fogarty, Daniel and Heller, Clayton and Clark, Charles W. and Edwards, Mark} } @article {17151, title = {Proposal for gravitational direct detection of dark matter}, journal = {Phys. Rev. D}, volume = {102}, year = {2020}, month = {Oct}, pages = {072003}, doi = {10.1103/PhysRevD.102.072003}, url = {https://link.aps.org/doi/10.1103/PhysRevD.102.072003}, author = {Carney, Daniel and Ghosh, Sohitri and Krnjaic, Gordan and Taylor, Jacob M.} } @article {pagano_quantum_2020, title = {Quantum approximate optimization of the long-range {Ising} model with a trapped-ion quantum simulator}, journal = {Proc. Natl. Acad. Sci. U. S. A.}, volume = {117}, number = {41}, year = {2020}, note = {Place: 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA Publisher: NATL ACAD SCIENCES Type: Article}, month = {oct}, pages = {25396{\textendash}25401}, abstract = {Quantum computers and simulators may offer significant advantages over their classical counterparts, providing insights into quantum many-body systems and possibly improving performance for solving exponentially hard problems, such as optimization and satisfiability. Here, we report the implementation of a low-depth Quantum Approximate Optimization Algorithm (QAOA) using an analog quantum simulator. We estimate the ground-state energy of the Transverse Field Ising Model with long-range interactions with tunable range, and we optimize the corresponding combinatorial classical problem by sampling the QAOA output with high-fidelity, single-shot, individual qubit measurements. We execute the algorithm with both an exhaustive search and closed-loop optimization of the variational parameters, approximating the ground-state energy with up to 40 trapped-ion qubits. We benchmark the experiment with bootstrapping heuristic methods scaling polynomially with the system size. We observe, in agreement with numerics, that the QAOA performance does not degrade significantly as we scale up the system size and that the runtime is approximately independent from the number of qubits. We finally give a comprehensive analysis of the errors occurring in our system, a crucial step in the path forward toward the application of the QAOA to more general problem instances.}, keywords = {computing, quantum, quantum algorithms, quantum information science, quantum simulation, trapped ions}, issn = {0027-8424}, doi = {10.1073/pnas.2006373117}, author = {Pagano, Guido and Bapat, Aniruddha and Becker, Patrick and Collins, Katherine S. and De, Arinjoy and Hess, Paul W. and Kaplan, Harvey B. and Kyprianidis, Antonis and Tan, Wen Lin and Baldwin, Christopher and Brady, Lucas T. and Deshpande, Abhinav and Liu, Fangli and Jordan, Stephen and Gorshkov, V, Alexey and Monroe, Christopher} } @article { ISI:000519631000004, title = {Quantum Brownian motion of a particle from Casimir-Polder interactions}, journal = {Phys. Rev. A}, volume = {101}, number = {3}, year = {2020}, month = {MAR 13}, pages = {032507}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study the fluctuation-induced dissipative dynamics of the quantized center-of-mass motion of a polarizable dielectric particle trapped near a surface. The particle{\textquoteright}s center of mass is treated as an open quantum system coupled to the electromagnetic field acting as its environment, with the resulting system dynamics described by a quantum Brownian motion master equation. The dissipation and decoherence of the particle{\textquoteright}s center of mass are characterized by the modified spectral density of the electromagnetic field that depends on surface losses and the strength of the classical trap field. Our results are relevant to experiments with levitated dielectric particles near surfaces, illustrating potential ways of mitigating fluctuation-induced decoherence while preparing such systems in macroscopic quantum states.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.101.032507}, author = {Sinha, Kanupriya and Subasi, Yigit} } @article { ISI:000513110500015, title = {Quantum cascade laser lives on the edge}, journal = {Nature}, volume = {578}, number = {7794}, year = {2020}, month = {FEB}, pages = {219-220}, publisher = {NATURE PUBLISHING GROUP}, type = {Editorial Material}, abstract = {Devices known as quantum cascade lasers produce useful terahertz radiation, but are typically highly sensitive to fabrication defects. This limitation has now been overcome using a property called topological robustness. Terahertz radiation from a topological laser.}, issn = {0028-0836}, author = {Mittal, Sunil and Waks, Edo} } @article { ISI:000576889300001, title = {Quantum geometry and stability of moire flatband ferromagnetism}, journal = {Phys. Rev. B}, volume = {102}, number = {16}, year = {2020}, month = {OCT 12}, pages = {165118}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Several moire systems created by various twisted bilayers have manifested magnetism under flatband conditions leading to enhanced interaction effects. We theoretically study stability of moire flatband ferromagnetism against collective excitations, with a focus on the effects of Bloch band quantum geometry. The spin magnon spectrum is calculated using different approaches, including Bethe-Salpeter equation, single mode approximation, and an analytical theory. One of our main results is an analytical expression for the spin stiffness in terms of the Coulomb interaction potential, the Berry curvatures, and the quantum metric tensor, where the last two quantities characterize the quantum geometry of moire bands. This analytical theory shows that Berry curvatures play an important role in stiffening the spin magnons. Furthermore, we construct an effective field theory for the magnetization fluctuations and show explicitly that skyrmion excitations bind an integer number of electrons that is proportional to the Bloch band Chern number and the skyrmion winding number.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.165118}, author = {Wu, Fengcheng and Das Sarma, S.} } @article { ISI:000519638100001, title = {Quantum Hall resistance dartboards using graphene p-n junction devices with Corbino geometries}, journal = {AIP Adv.}, volume = {10}, number = {3}, year = {2020}, month = {MAR 1}, pages = {035205}, publisher = {AMER INST PHYSICS}, type = {Article}, abstract = {The use of multiple current terminals on millimeter-scale graphene p-n junction devices fabricated with Corbino geometries, or quantum Hall resistance dartboards, has enabled the measurement of several fractional multiples of the quantized Hall resistance at the nu = 2 plateau (R-H approximate to 12 906 Omega). Experimentally obtained values agreed with the corresponding numerical simulations performed with the LTspice circuit simulator. More complicated designs of the quantum Hall resistance dartboard were simulated to establish the potential parameter space within which these Corbino-type devices could output resistance. Most importantly, these measurements support simpler processes of ultraviolet lithography as a more efficient means of scaling up graphene-based device sizes while maintaining sufficiently narrow junctions. (c) 2020 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).}, doi = {10.1063/1.5136315}, author = {Liu, I, C- and Patel, D. K. and Marzano, M. and Kruskopf, M. and Hill, H. M. and Rigosi, A. F.} } @article { ISI:000506585800002, title = {Quantum Lifshitz criticality in a frustrated two-dimensional XY model}, journal = {Phys. Rev. B}, volume = {101}, number = {3}, year = {2020}, month = {JAN 9}, pages = {035114}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Antiferromagnetic quantum spin systems can exhibit a transition between collinear and spiral ground states, driven by frustration. Classically this is a smooth crossover and the crossover point is termed a Lifshitz point. Quantum fluctuations change the nature of the transition. In particular, it has been argued previously that in the two-dimensional (2D) case a spin liquid (SL) state is developed in the vicinity of the Lifshitz point, termed a Lifshitz SL. In the present work, using a field theory approach, we solve the Lifshitz quantum phase transition problem for the 2D frustrated XY model. Specifically, we show that, unlike the SU(2) symmetric Lifshitz case, in the XY model, the SL exists only at the critical point. At zero temperature we calculate nonuniversal critical exponents in the Neel and in the spin spiral state and relate these to properties of the SL. We also solve the transition problem at a finite temperature and discuss the role of topological excitations.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.035114}, author = {Kharkov, Yaroslav A. and Oitmaa, Jaan and Sushkov, Oleg P.} } @inbook {solomon_quantum_2020, title = {Quantum light from optically dressed quantum dot states in microcavities}, booktitle = {Semiconductor Quantum Science and Technology}, series = {Semiconductors and {Semimetals}}, volume = {105}, year = {2020}, note = {ISSN: 0080-8784 Journal Abbreviation: Semicond. Semimet. Type: Article; Book Chapter}, pages = {305{\textendash}346}, publisher = {ELSEVIER ACADEMIC PRESS INC}, organization = {ELSEVIER ACADEMIC PRESS INC}, isbn = {978-0-12-823773-1}, doi = {10.1016/bs.semsem.2020.10.004}, author = {Solomon, Glenn S. and Muller, Andreas and Flagg, Edward}, editor = {Cundiff, ST and Kira, M} } @conference {hao_quantum_2020, title = {Quantum {Limits} of {Optical} {Beam} {Deflection} {Measurements} of a {Nanomechanical} {Resonator}}, booktitle = {Conference on Lasers and Electro-Optics (CLEO)}, series = {Conference on {Lasers} and {Electro}-{Optics}}, year = {2020}, note = {Backup Publisher: IEEE ISSN: 2160-9020 Type: Proceedings Paper}, publisher = {IEEE}, organization = {IEEE}, abstract = {Optical lever detection is a simple and robust method to measure small displacements. We report on our experimental efforts toward reaching and surpassing the quantum backaction limits of this method when probing a high Q nanomechanical resonator. (C) 2020 The Author(s)

}, isbn = {978-1-943580-76-7}, author = {Hao, Shan and Singh, Robinjeet and Purdy, Thomas P.} } @article { ISI:000510146100001, title = {Quantum many-body scar states with emergent kinetic constraints and finite-entanglement revivals}, journal = {Phys. Rev. B}, volume = {101}, number = {2}, year = {2020}, month = {JAN 29}, pages = {024306}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We construct a set of exact, highly excited eigenstates for a nonintegrable spin-1/2 model in one dimension that is relevant to experiments on Rydberg atoms in the antiblockade regime. These states provide a new solvable example of quantum many-body scars: their sub-volume-law entanglement and equal energy spacing allow for infinitely long-lived coherent oscillations of local observables following a suitable quantum quench. While previous works on scars have interpreted such oscillations in terms of the precession of an emergent macroscopic SU(2) spin, the present model evades this description due to a set of emergent kinetic constraints in the scarred eigenstates that are absent in the underlying Hamiltonian. We also analyze the set of initial states that give rise to periodic revivals, which persist as approximate revivals on a finite timescale when the underlying model is perturbed. Remarkably, a subset of these initial states coincides with the family of area-law entangled Rokhsar-Kivelson states shown by Lesanovsky to be exact ground states for a class of models relevant to experiments on Rydberg-blockaded atomic lattices.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.024306}, author = {Iadecola, Thomas and Schecter, Michael} } @article {zhu_quantum_2020, title = {Quantum origami: {Transversal} gates for quantum computation and measurement of topological order}, journal = {Phys. Rev. Res.}, volume = {2}, number = {1}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {mar}, abstract = {In topology, a torus remains invariant under certain nontrivial transformations known as modular transformations. In the context of topologically ordered quantum states of matter supported on a torus geometry in real space, these transformations encode the braiding statistics and fusion rules of emergent anyonic excitations and thus serve as a diagnostic of topological order. Moreover, modular transformations of higher genus surfaces, e.g., a torus with multiple handles, can enhance the computational power of a topological state, in many cases providing a universal fault-tolerant set of gates for quantum computation. However, due to the intrusive nature of modular transformations, which abstractly involve global operations, physical implementations of them in local systems have remained elusive. Here, we show that by engineering an effectively folded manifold corresponding to a multilayer topological system, modular transformations can be applied in a single shot by independent local unitaries, providing a novel class of transversal logical gates for fault-tolerant quantum computation. Specifically, we demonstrate that multilayer topological states with appropriate boundary conditions and twist defects allow modular transformations to be effectively implemented by a finite sequence of local SWAP gates between the layers. We further provide methods to directly measure the modular matrices, and thus the fractional statistics of anyonic excitations, providing a novel way to directly measure topological order. A more general theory of transversal gates and the deep connection to anyon symmetry transformation and symmetry-enriched topological orders are also discussed.}, doi = {10.1103/PhysRevResearch.2.013285}, author = {Zhu, Guanyu and Hafezi, Mohammad and Barkeshli, Maissam} } @article { ISI:000570957900002, title = {Quantum oscillations from networked topological interfaces in a Weyl semimetal}, journal = {npj Quantum Mater.}, volume = {5}, number = {1}, year = {2020}, month = {SEP 7}, pages = {62}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {Layered transition metal chalcogenides are promising hosts of electronic Weyl nodes and topological superconductivity. MoTe(2)is a striking example that harbors both noncentrosymmetric T(d)and centrosymmetric T{\textquoteright} phases, both of which have been identified as topologically nontrivial. Applied pressure tunes the structural transition separating these phases to zero temperature, stabilizing a mixed T-d-T{\textquoteright} matrix that entails a network of interfaces between the two nontrivial topological phases. Here, we show that this critical pressure range is characterized by distinct coherent quantum oscillations, indicating that the difference in topology between topologically nonvtrivial T(d)and T{\textquoteright} phases gives rise to an emergent electronic structure: a network of topological interfaces. A rare combination of topologically nontrivial electronic structures and locked-in transformation barriers leads to this counterintuitive situation, wherein quantum oscillations can be observed in a structurally inhomogeneous material. These results further open the possibility of stabilizing multiple topological phases coexisting with superconductivity.}, doi = {10.1038/s41535-020-00264-8}, author = {Liu, I-Lin and Heikes, Colin and Yildirim, Taner and Eckberg, Chris and Metz, Tristin and Kim, Hyunsoo and Ran, Sheng and Ratcliff, William D. and Paglione, Johnpierre and Butch, Nicholas P.} } @article {17096, title = {Quantum simulation of hyperbolic space with circuit quantum electrodynamics: From graphs to geometry}, journal = {Phys. Rev. A}, volume = {102}, year = {2020}, month = {Sep}, pages = {032208}, abstract = {We show how quantum many-body systems on hyperbolic lattices with nearest-neighbor hopping and local interactions can be mapped onto quantum field theories in continuous negatively curved space. The underlying lattices have recently been realized experimentally with superconducting resonators and therefore allow for a table-top quantum simulation of quantum physics in curved background. Our mapping provides a computational tool to determine observables of the discrete system even for large lattices, where exact diagonalization fails. As an application and proof of principle we quantitatively reproduce the ground state energy, spectral gap, and correlation functions of the noninteracting lattice system by means of analytic formulas on the Poincar{\'e} disk, and show how conformal symmetry emerges for large lattices. This sets the stage for studying interactions and disorder on hyperbolic graphs in the future. Importantly, our analysis reveals that even relatively small discrete hyperbolic lattices emulate the continuous geometry of negatively curved space, and thus can be used to experimentally resolve fundamental open problems at the interface of interacting many-body systems, quantum field theory in curved space, and quantum gravity.

}, keywords = {hyperbolic geometry, quantum simulation}, doi = {10.1103/PhysRevA.102.032208}, url = {https://link.aps.org/doi/10.1103/PhysRevA.102.032208}, author = {Boettcher, Igor and Bienias, Przemyslaw and Belyansky, Ron and Kollar, Alicia J. and Gorshkov, Alexey V.} } @article {anastopoulos_quantum_2020, title = {Quantum superposition of two gravitational cat states}, journal = {Class. Quantum Gravity}, volume = {37}, number = {23}, year = {2020}, note = {Place: TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND Publisher: IOP PUBLISHING LTD Type: Article}, month = {dec}, abstract = {We extend our earlier work [1] on probing a gravitational cat state (gravcat) to the quantum superposition of two gravcats in an exemplary model and in Bose-Einstein condensates (BEC). In addition to its basic theoretical values in gravitational quantum physics and macroscopic quantum phenomena, this investigation can provide some theoretical support to experimental proposals for measuring gravity-induced entanglement and the quantum nature of perturbative gravity. In the first part we consider cat states generated by double-well potentials. A pair of gravcats, each approximated as a two-level system, is characterized by gravity-induced Rabi oscillations, and by gravity-induced entanglement of its energy eigenstates. In the second part we turn to a (non-relativistic) quantum field theory description and derive a gravitational Gross-Pitaevsky equation for gravcats formed in BEC. Using a mathematical analogy to quantum rotors, we explore the properties of the two-gravcat system for BECs, its physical consequences and observational possibilities. Finally we discuss our results in comparison to predictions of alternative quantum theories, and we explain their implications.}, keywords = {Bose Einstein condensates, entanglement, gravitational decoherence, gravitational quantum physics, quantum superpositions}, issn = {0264-9381}, doi = {10.1088/1361-6382/abbe6f}, author = {Anastopoulos, C. and Hu, B. L.} } @article { ISI:000556360300013, title = {Quantum walks and Dirac cellular automata on a programmable trapped-ion quantum computer}, journal = {Nat. Commun.}, volume = {11}, number = {1}, year = {2020}, month = {JUL 24}, pages = {3720}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {The quantum walk formalism is a widely used and highly successful framework for modeling quantum systems, such as simulations of the Dirac equation, different dynamics in both the low and high energy regime, and for developing a wide range of quantum algorithms. Here we present the circuit-based implementation of a discrete-time quantum walk in position space on a five-qubit trapped-ion quantum processor. We encode the space of walker positions in particular multi-qubit states and program the system to operate with different quantum walk parameters, experimentally realizing a Dirac cellular automaton with tunable mass parameter. The quantum walk circuits and position state mapping scale favorably to a larger model and physical systems, allowing the implementation of any algorithm based on discrete-time quantum walks algorithm and the dynamics associated with the discretized version of the Dirac equation.}, issn = {2041-1723}, doi = {10.1038/s41467-020-17519-4}, author = {Alderete, C. Huerta and Singh, Shivani and Nhung H Nguyen and Zhu, Daiwei and Balu, Radhakrishnan and Monroe, Christopher and Chandrashekar, C. M. and Linke, Norbert M.} } @article { ISI:000555323500001, title = {Quenched vs Annealed: Glassiness from SK to SYK}, journal = {Phys. Rev. X}, volume = {10}, number = {3}, year = {2020}, month = {AUG 4}, pages = {031026}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We show that any Sachdev-Ye-Kitaev- (SYK) like model with finite-body interactions among local degrees of freedom, e.g., bosons or spins, has a fundamental difference from the standard fermionic model: The former model fails to be described by an annealed free energy at low temperature. In this respect, such models more closely resemble spin glasses. We demonstrate this by two means: first, a general theorem proving that the annealed free energy is divergent at low temperature in any model with a tensor product Hilbert space, and second, a replica treatment of two prominent examples which exhibit phase transitions from an {\textquoteleft}{\textquoteleft}annealed{{\textquoteright}{\textquoteright}} phase to a {\textquoteleft}{\textquoteleft}nonannealed{{\textquoteright}{\textquoteright}} phase as a function of the temperature. We further show that this effect appears only at O(N)th order in a 1/N expansion, even though lower-order terms misleadingly seem to converge. Our results prove that the nonbosonic nature of the particles in the SYK model is an essential ingredient for its physics, highlight connections between local models and spin glasses, and raise important questions as to the role of fermions and/or glassiness in holography.}, issn = {2160-3308}, doi = {10.1103/PhysRevX.10.031026}, author = {Baldwin, C. L. and Swingle, B.} } @article {barker_radiofrequency_2020, title = {A radiofrequency voltage-controlled current source for quantum spin manipulation}, journal = {Rev. Sci. Instrum.}, volume = {91}, number = {10}, year = {2020}, note = {Place: 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA Publisher: AMER INST PHYSICS Type: Article}, month = {oct}, abstract = {We present a wide-bandwidth, voltage-controlled current source that is easily integrated with radiofrequency magnetic field coils. Our design uses current feedback to compensate for the frequency-dependent impedance of a radiofrequency antenna. We are able to deliver peak currents greater than 100 mA over a 300 kHz to 54 MHz frequency span. The radiofrequency current source fits onto a printed circuit board smaller than 4 cm(2) and consumes less than 1.3 W of power. It is suitable for use in deployable quantum sensors and nuclear magnetic resonance systems.}, issn = {0034-6748}, doi = {10.1063/5.0011813}, author = {Barker, D. S. and Restelli, A. and Fedchak, J. A. and Scherschligt, J. and Eckel, S.} } @article {caravelli_random_2020, title = {Random quantum batteries}, journal = {Phys. Rev. Res.}, volume = {2}, number = {2}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {apr}, abstract = {Quantum nanodevices are fundamental systems in quantum thermodynamics that have been the subject of profound interest in recent years. Among these, quantum batteries play a very important role. In this paper we lay down a theory of random quantum batteries and provide a systematic way of computing the average work and work fluctuations in such devices by investigating their typical behavior. We show that the performance of random quantum batteries exhibits typicality and depends only on the spectral properties of the time evolving operator, the initial state, and the measuring Hamiltonian. At given revival times a random quantum battery features a quantum advantage over classical random batteries. Our method is particularly apt to be used both for exactly solvable models like the Jaynes-Cummings model or in perturbation theory, e.g., systems subject to harmonic perturbations. We also study the setting of quantum adiabatic random batteries.}, doi = {10.1103/PhysRevResearch.2.023095}, author = {Caravelli, Francesco and Coulter-De Wit, Ghislaine and Pedro Garcia-Pintos, Luis and Hamma, Alioscia} } @article {anderson_realization_2020, title = {Realization of a deeply subwavelength adiabatic optical lattice}, journal = {Phys. Rev. Res.}, volume = {2}, number = {1}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {feb}, abstract = {We propose and describe our realization of a deeply subwavelength optical lattice for ultracold neutral atoms using N resonantly Raman-coupled internal degrees of freedom. Although counterpropagating lasers with wavelength. provided two-photon Raman coupling, the resultant lattice period was lambda/2N, an N-fold reduction as compared to the conventional lambda/2 lattice period. We experimentally demonstrated this lattice built from the three F = 1 Zeeman states of a Rb-87 Bose-Einstein condensate, and generated a lattice with a lambda/6 = 132 nm period from lambda = 790 nm lasers. Lastly, we show that adding an additional rf-coupling field converts this lattice into a superlattice with N wells uniformly spaced within the original lambda/2 unit cell.}, doi = {10.1103/PhysRevResearch.2.013149}, author = {Anderson, R. P. and Trypogeorgos, D. and Valdes-Curiel, A. and Liang, Q-Y and Tao, J. and Zhao, M. and Andrijauskas, T. and Juzeliunas, G. and Spielman, I. B.} } @article { ISI:000526522500002, title = {Realization of a stroboscopic optical lattice for cold atoms with subwavelength spacing}, journal = {Phys. Rev. A}, volume = {101}, number = {4}, year = {2020}, month = {APR 17}, pages = {041603}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Optical lattices are typically created via the ac Stark shift and are limited by diffraction to periodicities >= lambda/2, where. is the wavelength of light used to create them. Lattices with smaller periodicities may be useful for many-body physics with cold atoms and can be generated by stroboscopic application of a phase-shifted lattice with subwavelength features. Here we demonstrate a lambda/4-spaced lattice by stroboscopically applying optical Kronig-Penney-like potentials which are generated using spatially dependent dark states. We directly probe the periodicity of the lambda/4-spaced lattice by measuring the average probability density of the atoms loaded into the ground band of the lattice. We measure lifetimes of atoms in this lattice and discuss the mechanisms that limit the applicability of this stroboscopic approach.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.101.041603}, author = {Tsui, T-C and Wang, Y. and Subhankar, S. and Porto, V, J. and Rolston, S. L.} } @article { ISI:000550577700002, title = {Real-time dynamics of string breaking in quantum spin chains}, journal = {Phys. Rev. B}, volume = {102}, number = {1}, year = {2020}, month = {JUL 21}, pages = {014308}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {String breaking is a central dynamical process in theories featuring confinement, where a string connecting two charges decays at the expense of the creation of new particle-antiparticle pairs. Here, we show that this process can also be observed in quantum Ising chains where domain walls get confined either by a symmetry-breaking field or by long-range interactions. We find that string breaking occurs, in general, as a two-stage process. First, the initial charges remain essentially static and stable. The connecting string, however, can become a dynamical object. We develop an effective description of this motion, which we find is strongly constrained. In the second stage, which can be severely delayed due to these dynamical constraints, the string finally breaks. We observe that the associated timescale can depend crucially on the initial separation between domain walls and can grow by orders of magnitude by changing the distance by just a few lattice sites. We discuss how our results generalize to one-dimensional confining gauge theories and how they can be made accessible in quantum simulator experiments such as Rydberg atoms or trapped ions.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.014308}, author = {Verdel, Roberto and Liu, Fangli and Whitsitt, Seth and Gorshkov, V, Alexey and Heyl, Markus} } @article { ISI:000527910200017, title = {Reflection and Time Reversal Symmetry Enriched Topological Phases of Matter: Path Integrals, Non-orientable Manifolds, and Anomalies}, journal = {Commun. Math. Phys.}, volume = {374}, number = {2}, year = {2020}, month = {MAR}, pages = {1021-1124}, publisher = {SPRINGER}, type = {Article}, abstract = {We study symmetry-enriched topological (SET) phases in 2+1 space-time dimensions with spatial reflection and/or time-reversal symmetries. We provide a systematic construction of a wide class of reflection and time-reversal SET phases in terms of a topological path integral defined on general space-time manifolds. An important distinguishing feature of different topological phases with reflection and/or time-reversal symmetry is the value of the path integral on non-orientable space-time manifolds. We derive a simple general formula for the path integral on the manifold Sigma(2) x S-1, where Sigma(2) is a two-dimensional non-orientable surface and S-1 is a circle. This also gives an expression for the ground state degeneracy of the SET on the surface Sigma(2) that depends on the reflection symmetry fractionalization class, generalizing the Verlinde formula for ground state degeneracy on orientable surfaces. Consistency of the action of the mapping class group on non-orientable manifolds leads us to a constraint that can detect when a time-reversal or reflection SET phase is anomalous in (2+1)D and, thus, can only exist at the surface of a (3+1)D symmetry protected topological (SPT) state. Given a (2+1)D reflection and/or time-reversal SET phase, we further derive a general formula that determines which (3+1)D reflection and/or time-reversal SPT phase hosts the (2+1)D SET phase as its surface termination. A number of explicit examples are studied in detail.}, issn = {0010-3616}, doi = {10.1007/s00220-019-03475-8}, author = {Barkeshli, Maissam and Bonderson, Parsa and Cheng, Meng and Jian, Chao-Ming and Walker, Kevin} } @article {barkeshli_relative_2020, title = {Relative anomalies in (2+1){D} symmetry enriched topological states}, journal = {SciPost Phys.}, volume = {8}, number = {2}, year = {2020}, note = {Place: C/O J S CAUX, INST PHYSICS, UNIV AMSTERDAM, AMSTERDAM, 1098 XH, NETHERLANDS Publisher: SCIPOST FOUNDATION Type: Article}, month = {feb}, abstract = {Certain patterns of symmetry fractionalization in topologically ordered phases of matter are anomalous, in the sense that they can only occur at the surface of a higher dimensional symmetry-protected topological (SPT) state. An important question is to determine how to compute this anomaly, which means determining which SPT hosts a given symmetry-enriched topological order at its surface. While special cases are known, a general method to compute the anomaly has so far been lacking. In this paper we propose a general method to compute relative anomalies between different symmetry fractionalization classes of a given (2+1)D topological order. This method applies to all types of symmetry actions, including anyon-permuting symmetries and general space-time reflection symmetries. We demonstrate compatibility of the relative anomaly formula with previous results for diagnosing anomalies for Z(2)(T) space-time reflection symmetry (e.g. where time-reversal squares to the identity) and mixed anomalies for U(1) x Z(2)(T) and U (1) (sic) Z(2)(T) symmetries. We also study a number of additional examples, including cases where space-time reflection symmetries are intertwined in non-trivial ways with unitary symmetries, such as Z(4)(T) and mixed anomalies for Z(2) x Z(2)(T) symmetry, and unitary Z(2) x Z(2) symmetry with non-trivial anyon permutations.}, issn = {2542-4653}, doi = {10.21468/SciPostPhys.8.2.028}, author = {Barkeshli, Maissam and Cheng, Meng} } @article { ISI:000510386300006, title = {Reversible fluxon logic: Topological particles allow ballistic gates along one-dimensional paths}, journal = {Phys. Rev. B}, volume = {101}, number = {1}, year = {2020}, month = {JAN 31}, pages = {014516}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {As we reach the end of Moore{\textquoteright}s law, digital logic uses irreversible logic gates whose energy consumption has been scaled toward a lower limit. Reversible logic gates can provide a dramatic energy-efficient alternative, but rely on reversible dynamics. Here, we introduce a set of superconducting reversible gates that are powered alone by the inertia of the digital input states, contrasting existing adiabatic prototypes which are powered by an external adiabatic drive. The classic model of an inertia-powered reversible gate uses ballistic particles which scatter in two dimensions, where the digital state is represented by the particle path. Our ballistic gates use as the bit state the topological charge (polarity) of a fluxon moving along a long Josephson junction (LJJ) such that the particle path is confined to one dimension. The fundamental structures of our reversible fluxon logic (RFL) are one-bit gates which consist of two LJJs connected by a circuit interface that comprises three large-capacitor Josephson junctions (JJs). Numerical simulations show how a fluxon approaching the interface under its own inertia converts its energy to an oscillating evanescent field, from which in turn a new fluxon is generated in the other LJJ. We find that this resonant forward scattering of a fluxon across the interface requires large capacitances of the interface JJs because they enable a conversion between bound-evanescent and traveling fluxon states (without external power). Importantly, depending on the circuit parameters, the new fluxon may have either the original or the inverted polarity, and these two processes constitute the fundamental identity and NOT operations of the logic. Based on these one-bit RFL gates, we design and study a related two-bit RFL gate which shows that fluxons can exhibit conditional polarity change. Energy efficiency is accomplished because only a small fraction of the fluxon energy is transferred to modes other than the intended fluxon. Simulations show that over 97\% of the total fluxon energy is preserved during gate operations, in contrast to irreversible gates where the entire bit energy is consumed in bit switching. To provide insight into these phenomena, we analyze the one-bit gate circuits with a collective-coordinate model which describes the field in each LJJ as a combination of fluxon and mirror antifluxon. This allows us to reduce the many junction circuit (the three interface JJs and the many JJs approximating the LJJs, solved numerically) to that of two coupled degrees of freedom that each represent a particle. The evolution of the reduced model agrees quantitatively with the full circuit simulations and validates the use of the mirror-fluxon ansatz. Parameter tolerances are calculated for the proposed circuits and indicate that RFL gates can be manufactured and tested.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.014516}, author = {Wustmann, W. and Osborn, K. D.} } @article {monteiro_search_2020, title = {Search for {Composite} {Dark} {Matter} with {Optically} {Levitated} {Sensors}}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {18}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {oct}, abstract = {Results are reported from a search for a class of composite dark matter models with feeble long-range interactions with normal matter. We search for impulses arising from passing dark matter particles by monitoring the mechanical motion of an optically levitated nanogram mass over the course of several days. Assuming such particles constitute the dominant component of dark matter, this search places upper limits on their interaction with neutrons of a(n) {\textless}= 1.2 x 10(-7) at 95\% confidence for dark matter masses between 1 and 10 TeV and mediator masses m(phi) {\textless}= 0.1 eV. Because of the large enhancement of the cross section for dark matter to coherently scatter from a nanogram mass (similar to 10(29) times that for a single neutron) and the ability to detect momentum transfers as small as similar to 200 MeV/c, these results provide sensitivity to certain classes of composite dark matter models that substantially exceeds existing searches, including those employing kilogram- or ton-scale targets. Extensions of these techniques can enable directionally sensitive searches for a broad class of previously inaccessible heavy dark matter candidates.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.181102}, author = {Monteiro, Fernando and Afek, Gadi and Carney, Daniel and Krnjaic, Gordan and Wang, Jiaxiang and Moore, David C.} } @article {brewer_signal_2020, title = {Signal advance and delay due to an optical phase-sensitive amplifier}, journal = {Opt. Express}, volume = {28}, number = {10}, year = {2020}, note = {Place: 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA Publisher: OPTICAL SOC AMER Type: Article}, month = {may}, pages = {14573{\textendash}14579}, abstract = {Fast and slow light media exploit a steep frequency dependence in their index of refraction in order to advance or delay a modulated signal. Here we observe a qualitatively similar advance and delay from an optical phase-sensitive amplifier (PSA). Unlike in the case of slow and fast light, this effect is due to a redistribution of power between imbalanced signal sidebands, and the advance or delay is dependent on the optical phase of the input. The PSA adds energy and also changes the frequency spectrum of the input. We show that the advances and delays observed in a PSA implemented using four-wave mixing in a warm rubidium vapor are consistent with the expected behavior of an ideal PSA.}, issn = {1094-4087}, doi = {10.1364/OE.392789}, author = {Brewer, Nicholas R. and Li, Tian and Jones, Kevin M. and Lett, Paul D.} } @article { ISI:000548153300005, title = {Signaling and scrambling with strongly long-range interactions}, journal = {Phys. Rev. A}, volume = {102}, number = {1}, year = {2020}, month = {JUL 8}, pages = {010401}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Strongly long-range interacting quantum systems-those with interactions decaying as a power law 1/r(alpha) in the distance r on a D-dimensional lattice for alpha <= D-have received significant interest in recent years. They are present in leading experimental platforms for quantum computation and simulation, as well as in theoretical models of quantum-information scrambling and fast entanglement creation. Since no notion of locality is expected in such systems, a general understanding of their dynamics is lacking. In a step towards rectifying this problem, we prove two Lieb-Robinson-type bounds that constrain the time for signaling and scrambling in strongly long-range interacting systems, for which no tight bounds were previously known. Our first bound applies to systems mappable to free-particle Hamiltonians with long-range hopping, and is saturable for alpha <= D/2. Our second bound pertains to generic long-range interacting spin Hamiltonians and gives a tight lower bound for the signaling time to extensive subsets of the system for all alpha < D. This many-site signaling time lower bounds the scrambling time in strongly long-range interacting systems.}, issn = {1050-2947}, doi = {10.1103/PhysRevA.102.010401}, author = {Guo, Andrew Y. and Tran, Minh C. and Childs, Andrew M. and Gorshkov, V, Alexey and Gong, Zhe-Xuan} } @article {drake_simplify_2020, title = {Simplify your life}, journal = {Nat. Phys.}, volume = {16}, number = {12}, year = {2020}, note = {Place: HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY Publisher: NATURE RESEARCH Type: Editorial Material}, month = {dec}, pages = {1242}, abstract = {Within the Hartree atomic unit systems, the Schrodinger equation becomes parameter free. But there{\textquoteright}s more to it than making a student{\textquoteright}s life easier, as Gordon Drake and Eite Tiesinga recount.}, issn = {1745-2473}, doi = {10.1038/s41567-020-01095-x}, author = {Drake, Gordon W. F. and Tiesinga, Eite} } @conference {sabines-chesterking_single-emitter-sensitivity_2020, title = {Single-emitter-sensitivity in flow cytometry verified by quantum measurement}, booktitle = {Conference on Lasers and Electro-Optics (CLEO)}, series = {Conference on {Lasers} and {Electro}-{Optics}}, year = {2020}, note = {Backup Publisher: IEEE ISSN: 2160-9020 Type: Proceedings Paper}, publisher = {IEEE}, organization = {IEEE}, abstract = {We demonstrate single quantum emitter sensitivity in a flow cytometer by measuring the second order correlation function to be g((2))(0) = 0.5(1). (C) 2020 The Author(s)

}, isbn = {978-1-943580-76-7}, author = {Sabines-Chesterking, Javier and Burenkov, Ivan A. and Polyakov, V, Sergey} } @article { ISI:000531592100001, title = {Single-photon sources: Approaching the ideal through multiplexing}, journal = {Rev. Sci. Instrum.}, volume = {91}, number = {4}, year = {2020}, month = {APR 1}, pages = {041101}, publisher = {AMER INST PHYSICS}, type = {Review}, abstract = {We review the rapid recent progress in single-photon sources based on multiplexing multiple probabilistic photon-creation events. Such multiplexing allows higher single-photon probabilities and lower contamination from higher-order photon states. We study the requirements for multiplexed sources and compare various approaches to multiplexing using different degrees of freedom.}, issn = {0034-6748}, doi = {10.1063/5.0003320}, author = {Meyer-Scott, Evan and Silberhorn, Christine and Migdall, Alan} } @article { ISI:000511450000006, title = {Spatial Coherence of Spin-Orbit-Coupled Bose Gases}, journal = {Phys. Rev. Lett.}, volume = {124}, number = {5}, year = {2020}, month = {FEB 6}, pages = {053605}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Spin-orbit-coupled Bose-Einstein condensates (SOBECs) exhibit two new phases of matter, now known as the stripe and plane-wave phases. When two interacting spin components of a SOBEC spatially overlap, density modulations with periodicity given by the spin-orbit coupling strength appear. In equilibrium, these components fully overlap in the miscible stripe phase and overlap only in a domain wall in the immiscible plane-wave phase. Here we probe the density modulation present in any overlapping region with optical Bragg scattering and observe the sudden drop of Bragg scattering as the overlapping region shrinks. Using an atomic analog of the Talbot effect, we demonstrate the existence of long-range coherence between the different spin components in the stripe phase and surprisingly even in the phase-separated plane-wave phase.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.124.053605}, author = {Putra, Andika and Salces-Carcoba, F. and Yue, Yuchen and Sugawa, Seiji and Spielman, I. B.} } @article {throckmorton_spontaneous_2020, title = {Spontaneous symmetry breaking in a honeycomb lattice subject to a periodic potential}, journal = {Phys. Rev. Res.}, volume = {2}, number = {2}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {may}, abstract = {Motivated by recent developments in twisted bilayer graphene moire superlattices, we investigate the effects of electron-electron interactions in a honeycomb lattice with an applied periodic potential using a finite-temperature Wilson-Fisher momentum shell renormalization group (RG) approach. We start with a low-energy effective theory for such a system, at first giving a discussion of the most general case in which no point group symmetry is preserved by the applied potential, and then focusing on the special case in which the potential preserves a D-3 point group symmetry. As in similar studies of bilayer graphene, we find that, while the coupling constants describing the interactions diverge at or below a certain critical temperature T = T-c, it turns out that ratios of these constants remain finite and in fact provide information about what types of orders the system is becoming unstable to. However, in contrast to these previous studies, we only find isolated fixed rays, indicating that these orders are likely unstable to perturbations to the coupling constants. Our RG analysis leads to the qualitative conclusion that the emergent interaction-induced symmetry-breaking phases in this model system, and perhaps therefore by extension in twisted bilayer graphene, are generically unstable and fragile, and may thus manifest strong sample dependence.}, doi = {10.1103/PhysRevResearch.2.023225}, author = {Throckmorton, Robert E. and Das Sarma, S.} } @conference {moille_stable_2020, title = {Stable {Dissipative} {Kerr} {Solitons} in a {AlGaAs} {Microresonator} {Through} {Cryogenic} {Operation}}, booktitle = {Conference on Lasers and Electro-Optics (CLEO)}, series = {Conference on {Lasers} and {Electro}-{Optics}}, year = {2020}, note = {Backup Publisher: IEEE ISSN: 2160-9020 Type: Proceedings Paper}, publisher = {IEEE}, organization = {IEEE}, abstract = {We demonstrate stable microresonator Kerr solitons in an Al0.2Ga0.8As-on-insulator resonator thanks to cryogenic quenching of the thermorefractive effect. Reaching such a phase-stable state is a prerequisite to fully exploit the potential of this platform. (C) 2020 The Author(s)

}, isbn = {978-1-943580-76-7}, author = {Moille, Gregory and Chang, Lin and Xie, Weiqiang and Lu, Xiyuan and Davanco, Marcelo and Bowers, John E. and Srinivasan, Kartik} } @article { ISI:000533504100003, title = {State-Dependent Optical Lattices for the Strontium Optical Qubit}, journal = {Phys. Rev. Lett.}, volume = {124}, number = {20}, year = {2020}, month = {MAY 18}, pages = {203201}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We demonstrate state-dependent optical lattices for the Sr optical qubit at the tune-out wavelength for its ground state. We tightly trap excited state atoms while suppressing the effect of the lattice on ground state atoms by more than 4 orders of magnitude. This highly independent control over the qubit states removes inelastic excited state collisions as the main obstacle for quantum simulation and computation schemes based on the Sr optical qubit. Our results also reveal large discrepancies in the atomic data used to calibrate the largest systematic effect of Sr optical lattice clocks.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.124.203201}, author = {Heinz, A. and Park, A. J. and Santi, N. and Trautmann, J. and Porsev, S. G. and Safronova, M. S. and Bloch, I and Blatt, S.} } @article {saha_strongly_2020, title = {Strongly interacting spin-orbit coupled {Bose}-{Einstein} condensates in one dimension}, journal = {Phys. Rev. Res.}, volume = {2}, number = {1}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {mar}, abstract = {We theoretically study dilute superfluidity of spin-1 bosons with antiferromagnetic interactions and synthetic spin-orbit coupling (SOC) in a one-dimensional lattice. Employing a combination of density matrix renormalization group and quantum field theoretical techniques we demonstrate the appearance of a robust superfluid spin-liquid phase in which the spin sector of this spinor Bose-Einstein condensate remains quantum disordered even after introducing quadratic Zeeman and helical magnetic fields. Despite remaining disordered, the presence of these symmetry-breaking fields lifts the perfect spin-charge separation and thus the nematic correlators obey power-law behavior. We demonstrate that, at strong coupling, the SOC induces a charge density wave state that is not accessible in the presence of linear and quadratic Zeeman fields alone. In addition, the SOC induces oscillations in the spin and nematic expectation values as well as the bosonic Green{\textquoteright}s function. These nontrivial effects of an SOC are suppressed under the application of a large quadratic Zeeman field. We discuss how our results could be observed in experiments on ultracold gases of Na-23 in an optical lattice.}, doi = {10.1103/PhysRevResearch.2.013252}, author = {Saha, Siddhartha and Konig, E. J. and Lee, Junhyun and Pixley, J. H.} } @article { ISI:000505984100002, title = {Subband occupation in semiconductor-superconductor nanowires}, journal = {Phys. Rev. B}, volume = {101}, number = {4}, year = {2020}, month = {JAN 7}, pages = {045405}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Subband occupancy (i.e., the number of occupied confinement-induced subbands of the semiconductor wire) is a key physical parameter determining the topological properties of superconductor-semiconductor hybrid systems investigated in the context of the search for non-Abelian Majorana zero modes. We theoretically study the subband occupation of semiconductor nanowire devices as a function of the applied gate potential, the semiconductor-superconductor (SM-SC) work function difference, and the surface charge density by solving self-consistently the Schrodinger-Poisson equations for the conduction electrons of the semiconductor nanowire. Realistic surface charge densities, which are responsible for band bending, are shown to significantly increase the number of occupied subbands, making it difficult or impossible to reach a regime where only a few subbands are occupied. We also show that the energy separation between subbands is significantly reduced in the regime of many occupied subbands, with highly detrimental consequences for the realization and observation of robust Majorana zero modes. As a consequence, the requirements for the realization of robust topological superconductivity and Majorana zero modes should include a low value of the chemical potential, consistent with the occupation of only a few subbands. Finally, we show that the local density of states on the exposed nanowire facets provides a powerful tool for identifying a regime with many occupied subbands and is capable of providing additional critical information regarding the feasibility of Majorana physics in semiconductor-superconductor devices. In our work we address both InAs/Al and InSb/Al superconductor-nanowire hybrid systems of current experimental interest.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.101.045405}, author = {Woods, Benjamin D. and Das Sarma, Sankar and Stanescu, Tudor D.} } @article {19026, title = {Symmetry Breaking and Error Correction in Open Quantum Systems}, journal = {Phys. Rev. Lett.}, volume = {125}, year = {2020}, month = {Dec}, pages = {240405}, abstract = {Symmetry-breaking transitions are a well-understood phenomenon of closed quantum systems in quantum optics, condensed matter, and high energy physics. However, symmetry breaking in open systems is less thoroughly understood, in part due to the richer steady-state and symmetry structure that such systems possess. For the prototypical open system{\textemdash}a Lindbladian{\textemdash}a unitary symmetry can be imposed in a {\textquotedblleft}weak{\textquotedblright} or a {\textquotedblleft}strong{\textquotedblright} way. We characterize the possible\ Zn\ symmetry-breaking transitions for both cases. In the case of\ Z2, a weak-symmetry-broken phase guarantees at most a classical bit steady-state structure, while a strong-symmetry-broken phase admits a partially protected steady-state qubit. Viewing photonic cat qubits through the lens of strong-symmetry breaking, we show how to dynamically recover the logical information after any gap-preserving strong-symmetric error; such recovery becomes perfect exponentially quickly in the number of photons. Our study forges a connection between driven-dissipative phase transitions and error correction.

}, doi = {10.1103/PhysRevLett.125.240405}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.125.240405}, author = {Lieu, Simon and Belyansky, Ron and Young, Jeremy T. and Lundgren, Rex and Albert, Victor V. and Gorshkov, Alexey V.} } @article {wu_three-dimensional_2020, title = {Three-dimensional topological twistronics}, journal = {Phys. Rev. Res.}, volume = {2}, number = {2}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {apr}, abstract = {We introduce a theoretical framework for the concept of three-dimensional (3D) twistronics by developing a generalized Bloch band theory for 3D layered systems with a constant twist angle theta between successive layers. Our theory employs a nonsymmorphic symmetry that enables a precise definition of an effective out-of-plane crystal momentum, and also captures the in-plane moire pattern formed between neighboring twisted layers. To demonstrate topological physics that can be achieved through 3D twistronics, we present two examples. In the first example of chiral twisted graphite, Weyl nodes arise because of inversion-symmetry breaking, with theta-tuned transitions between type-I and type-II Weyl fermions, as well as magic angles at which the in-plane velocity vanishes. In the second example of a twisted Weyl semimetal, the twist in the lattice structure induces a chiral gauge field A that has a vortex-antivortex lattice configuration. Line modes bound to the vortex cores of the A field give rise to 3D Weyl physics in the moire scale. We also discuss possible experimental realizations of 3D twistronics.}, doi = {10.1103/PhysRevResearch.2.022010}, author = {Wu, Fengcheng and Zhang, Rui-Xing and Das Sarma, Sankar} } @article { ISI:000521105100002, title = {Time Evolution of Correlation Functions in Quantum Many-Body Systems}, journal = {Phys. Rev. Lett.}, volume = {124}, number = {11}, year = {2020}, month = {MAR 19}, pages = {110605}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We give rigorous analytical results on the temporal behavior of two-point correlation functions-also known as dynamical response functions or Green{\textquoteright}s functions-in closed many-body quantum systems. We show that in a large class of translation-invariant models the correlation functions factorize at late times \< A(t)B \>(beta) -\> \< A \>(beta) \< B \>(beta) , thus proving that dissipation emerges out of the unitary dynamics of the system. We also show that for systems with a generic spectrum the fluctuations around this late-time value are bounded by the purity of the thermal ensemble, which generally decays exponentially with system size. For autocorrelation functions we provide an upper bound on the timescale at which they reach the factorized late time value. Remarkably, this bound is only a function of local expectation values and does not increase with system size. We give numerical examples that show that this bound is a good estimate in nonintegrable models, and argue that the timescale that appears can be understood in terms of an emergent fluctuationdissipation theorem. Our study extends to further classes of two point functions such as the symmetrized ones and the Kubo function that appears in linear response theory, for which we give analogous results.

}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.124.110605}, author = {Alhambra, Alvaro M. and Riddell, Jonathon and Garcia-Pintos, Luis Pedro} } @article {nicholson_time-information_2020, title = {Time-information uncertainty relations in thermodynamics}, journal = {Nat. Phys.}, volume = {16}, number = {12}, year = {2020}, note = {Place: HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY Publisher: NATURE RESEARCH Type: Article}, month = {dec}, abstract = {Physical systems powering motion and creating structure in a fixed amount of time dissipate energy and produce entropy. Whether living, synthetic or engineered, systems performing these dynamic functions must balance dissipation and speed. Here, we show that rates of energy and entropy exchange are subject to a speed limit-a time-information uncertainty relation-imposed by the rates of change in the information content of the system. This uncertainty relation bounds the time that elapses before the change in a thermodynamic quantity has the same magnitude as its s.d. From this general bound, we establish a family of speed limits for heat, dissipated/chemical work and entropy depending on the experimental constraints on the system and its environment. In all of these inequalities, the timescale of transient dynamical fluctuations is universally bounded by the Fisher information. Moreover, they all have a mathematical form that mirrors the Mandelstam-Tamm version of the time-energy uncertainty relation in quantum mechanics. These bounds on the speed of arbitrary observables apply to transient systems away from thermodynamic equilibrium, independent of the physical constraints on the stochastic dynamics or their function. A time-information uncertainty relation in thermodynamics has been derived, analogous to the time-energy uncertainty relation in quantum mechanics, imposing limits on the speed of energy and entropy exchange between a system and external reservoirs.}, issn = {1745-2473}, doi = {10.1038/s41567-020-0981-y}, author = {Nicholson, Schuyler B. and Garcia-Pintos, Luis Pedro and del Campo, Adolfo and Green, Jason R.} } @article {17056, title = {Time-Resolving Quantum Measurement Enables Energy-Efficient, Large-Alphabet Communication}, journal = {PRX Quantum}, volume = {1}, year = {2020}, month = {Sep}, pages = {010308}, doi = {10.1103/PRXQuantum.1.010308}, url = {https://link.aps.org/doi/10.1103/PRXQuantum.1.010308}, author = {Burenkov, I.A. and Jabir, M.V. and Battou, A. and Polyakov, S.V.} } @article {vu_time-reversal-invariant_2020, title = {Time-reversal-invariant {C}-2-symmetric higher-order topological superconductors}, journal = {Phys. Rev. Res.}, volume = {2}, number = {4}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {nov}, abstract = {We propose a minimal lattice model for two-dimensional class DIII superconductors with C-2-protected higher-order topology. Although this class of superconductors cannot be topologically characterized by symmetry eigenvalues at high-symmetry momenta, we propose a simple Wannier-orbital-based real-space diagnosis to unambiguously capture the corresponding higher-order topology. We further identify and characterize a variety of conventional topological phases in our minimal model, including a weak topological superconductor and a nodal topological superconductor with chiral-symmetry protection. The disorder effect is also systematically studied to demonstrate the robustness of higher-order bulk-boundary correspondence. Our theory lays the groundwork for predicting and diagnosing C-2-protected higher-order topology in class DIII superconductors.}, doi = {10.1103/PhysRevResearch.2.043223}, author = {Vu, DinhDuy and Zhang, Rui-Xing and Das Sarma, S.} } @article {aasen_topological_2020, title = {Topological defect networks for fractons of all types}, journal = {Phys. Rev. Res.}, volume = {2}, number = {4}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, abstract = {Fracton phases exhibit striking behavior which appears to render them beyond the standard topological quantum field theory (TQFT) paradigm for classifying gapped quantum matter. Here, we explore fracton phases from the perspective of defect TQFTs and show that topological defect networks-networks of topological defects embedded in stratified 3+1-dimensional (3+1D) TQFTs-provide a unified framework for describing various types of gapped fracton phases. In this picture, the subdimensional excitations characteristic of fractonic matter are a consequence of mobility restrictions imposed by the defect network. We conjecture that all gapped phases, including fracton phases, admit a topological defect network description and support this claim by explicitly providing such a construction for many well-known fracton models, including the X-cube and Haah{\textquoteright}s B code. To highlight the generality of our framework, we also provide a defect network construction of a fracton phase hosting non-Abelian fractons. As a byproduct of this construction, we obtain a generalized membrane-net description for fractonic ground states as well as an argument that our conjecture implies no topological fracton phases exist in 2+1-dimensional gapped systems. Our paper also sheds light on techniques for constructing higher-order gapped boundaries of 3+1D TQFTs.}, doi = {10.1103/PhysRevResearch.2.043165}, author = {Aasen, David and Bulmash, Daniel and Prem, Abhinav and Slagle, Kevin and Williamson, Dominic J.} } @article { ISI:000554826100006, title = {Topological superconductivity, ferromagnetism, and valley-polarized phases in moire systems: Renormalization group analysis for twisted double bilayer graphene}, journal = {Phys. Rev. B}, volume = {102}, number = {8}, year = {2020}, month = {AUG 3}, pages = {085103}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Recent experiments have observed possible spin- and valley-polarized insulators and spin-triplet superconductivity in twisted double bilayer graphene, a moire structure consisting of a pair of Bernal-stacked bilayer graphene. Besides the continuously tunable bandwidths controlled by an applied displacement field and twist angle, these moire bands also possess Van Hove singularities near the Fermi surface and a field-dependent nesting which is far from perfect. Here we carry out a perturbative renormalization group analysis to unbiasedly study the competition among all possible instabilities in twisted double bilayer graphene and related systems with a similar Van Hove fermiology in the presence of weak but finite repulsive interactions. Our key finding is that there are several competing magnetic, valley, charge, and superconducting instabilities arising from interactions in twisted double bilayer graphene, which can be tuned by controlling the displacement field and the twist angle. In particular, we show that spin- or valley-polarized uniform instabilities generically dominate under moderate interactions smaller than the bandwidth, whereas p-wave spin-triplet topological superconductivity and exotic spin-singlet modulated paired state become important as the interactions decrease. Realization of our findings in general moire systems with a similar Van Hove fermiology should open up new opportunities for manipulating topological superconductivity and spin- or valley-polarized states in highly tunable platforms.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.085103}, author = {Hsu, Yi-Ting and Wu, Fengcheng and Das Sarma, S.} } @article {16646, title = {Towards analog quantum simulations of lattice gauge theories with trapped ions}, journal = {Phys. Rev. Research}, volume = {2}, year = {2020}, month = {Apr}, pages = {023015}, doi = {10.1103/PhysRevResearch.2.023015}, url = {https://link.aps.org/doi/10.1103/PhysRevResearch.2.023015}, author = {Davoudi, Zohreh and Hafezi, Mohammad and Monroe, Christopher and Pagano, Guido and Seif, Alireza and Shaw, Andrew} } @article {vu_tunneling_2020, title = {Tunneling conductance of long-range {Coulomb} interacting {Luttinger} liquid}, journal = {Phys. Rev. Res.}, volume = {2}, number = {2}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {may}, abstract = {The theoretical model of the short-range interacting Luttinger liquid predicts a power-law scaling of the density of states and the momentum distribution function around the Fermi surface, which can be readily tested through tunneling experiments. However, some physical systems have long-range interaction, most notably the Coulomb interaction, leading to significantly different behaviors from the short-range interacting system. In this paper, we revisit the tunneling theory for the one-dimensional electrons interacting via the long-range Coulomb force. We show that, even though in a small dynamic range of temperature and bias voltage the tunneling conductance may appear to have a power-law decay similar to short-range interacting systems, the effective exponent is scale dependent and slowly increases with decreasing energy. This factor may lead to the sample-to-sample variation in the measured tunneling exponents. We also discuss the crossover to a free Fermi gas at high energy and the effect of the finite size. Our work demonstrates that experimental tunneling measurements in one-dimensional electron systems should be interpreted with great caution when the system is a Coulomb Luttinger liquid.}, doi = {10.1103/PhysRevResearch.2.023246}, author = {Vu, DinhDuy and Iucci, Anibal and Das Sarma, S.} } @article {zhang_twist-angle_2020, title = {Twist-angle dependence of moire excitons in {WS2}/{MoSe2} heterobilayers}, journal = {Nat. Commun.}, volume = {11}, number = {1}, year = {2020}, note = {Place: HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY Publisher: NATURE RESEARCH Type: Article}, month = {nov}, abstract = {Moire lattices formed in twisted van der Waals bilayers provide a unique, tunable platform to realize coupled electron or exciton lattices unavailable before. While twist angle between the bilayer has been shown to be a critical parameter in engineering the moire potential and enabling novel phenomena in electronic moire systems, a systematic experimental study as a function of twist angle is still missing. Here we show that not only are moire excitons robust in bilayers of even large twist angles, but also properties of the moire excitons are dependant on, and controllable by, the moire reciprocal lattice period via twist-angle tuning. From the twist-angle dependence, we furthermore obtain the effective mass of the interlayer excitons and the electron inter-layer tunneling strength, which are difficult to measure experimentally otherwise. These findings pave the way for understanding and engineering rich moire-lattice induced phenomena in angle-twisted semiconductor van der Waals heterostructures. Here, the authors show that the properties of the moire excitons in twisted van der Waals bilayers of transition metal dichalcogenides are determined by the moire reciprocal lattice period, and can be controlled via twist-angle tuning.}, issn = {2041-1723}, doi = {10.1038/s41467-020-19466-6}, author = {Zhang, Long and Zhang, Zhe and Wu, Fengcheng and Wang, Danqing and Gogna, Rahul and Hou, Shaocong and Watanabe, Kenji and Taniguchi, Takashi and Kulkarni, Krishnamurthy and Kuo, Thomas and Forrest, Stephen R. and Deng, Hui} } @article {bienias_two_2020, title = {Two photon conditional phase gate based on {Rydberg} slow light polaritons}, journal = {J. Phys. B-At. Mol. Opt. Phys.}, volume = {53}, number = {5}, year = {2020}, note = {Place: TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND Publisher: IOP PUBLISHING LTD Type: Article}, month = {mar}, abstract = {We analyze the fidelity of a deterministic quantum phase gate (QPG) for two photons counterpropagating as polaritons through a cloud of Rydberg atoms under the condition of electromagnetically induced transparency (EIT). We provide analytical results for the phase shift of the quantum gate, and provide an estimation for all processes leading to a reduction to the gate fidelity. Especially, the influence of losses from the intermediate level, dispersion of the photon wave packet, scattering into additional polariton channels, finite lifetime of the Rydberg state, as well as effects of transverse size of the wave packets are accounted for. We show that the flatness of the effective interaction, caused by the blockade phenomena, suppresses the corrections due to the finite transversal size. This is a strength of Rydberg-EIT setup compared to other approaches. Finally, we provide the experimental requirements for the realization of a high fidelity QPG using Rydberg polaritons.}, keywords = {amo, quantum gate, Quantum optics, Rydberg polaritons, Rydbergs}, issn = {0953-4075}, doi = {10.1088/1361-6455/ab5bed}, author = {Bienias, Przemyslaw and Buechler, Hans Peter} } @article { ISI:000562002100002, title = {Two-dimensional electron self-energy: Long-range Coulomb interaction}, journal = {Phys. Rev. B}, volume = {102}, number = {8}, year = {2020}, month = {AUG 24}, pages = {085145}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The electron self-energy for long-range Coulomb interactions plays a crucial role in understanding the many-body physics of interacting electron systems (e.g., in metals and semiconductors) and has been studied extensively for decades. In fact, it is among the oldest and the most-investigated many-body problems in physics. However, there is a lack of an analytical expression for the self-energy Re Sigma((R)) (epsilon, T) when energy epsilon and temperature k(B)T are arbitrary with respect to each other (while both being still small compared with the Fermi energy). We revisit this problem and calculate analytically the self-energy on the mass shell for a two-dimensional electron system with Coulomb interactions in the high density limit r(s)<< 1, for temperature r(s)(3/2) << k(B)T/E-F << r(s) and energy r(s)(3/2) << vertical bar epsilon vertical bar << r(s). We provide the exact high-density analytical expressions for the real and imaginary parts of the electron self-energy with arbitrary value of epsilon/KBT, to the leading order in the dimensionless Coulomb coupling constant r(s), and to several higher than leading orders in k(B)T/r(s)E(F) and epsilon/r(s)E(F) . We also obtain the asymptotic behavior of the self-energy in the regimes vertical bar epsilon vertical bar << k(B)T and vertical bar epsilon vertical bar >> k(B)T. The higher-order terms have subtle and highly nontrivial compound logarithmic contributions from both epsilon and T, explaining why they have never before been calculated in spite of the importance of the subject matter.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.085145}, author = {Liao, Yunxiang and Buterakos, Donovan and Schecter, Mike and Das Sarma, Sankar} } @article { ISI:000515320000001, title = {Type II Photoinitiator and Tuneable Poly(Ethylene Glycol)-Based Materials Library for Visible Light Photolithography}, journal = {Tissue Eng. Part A}, volume = {26}, number = {5-6}, year = {2020}, month = {MAR 1}, pages = {292-304}, publisher = {MARY ANN LIEBERT, INC}, type = {Article}, abstract = {Stereolithography (SL) has several advantages over traditional biomanufacturing techniques such as fused deposition modeling, including increased speed, accuracy, and efficiency. While SL has been broadly used in tissue engineering for the fabrication of three-dimensional scaffolds that can mimic the in vivo environment for cell growth and tissue regeneration, lithographic printing is usually performed on single-component materials cured with ultraviolet light, severely limiting the versatility and cytocompatibility of such systems. In this study, we report a highly tunable, low-cost photoinitiator system that we used to establish a systematic library of crosslinked materials based on low molecular weight poly(ethylene glycol) diacrylate. We assessed the physicochemical properties, photocrosslinking efficiency, cost performance, and biocompatibility to demonstrate the capability of manufacturing a multimaterial complex tissue scaffold.

}, keywords = {bioink, multimaterial scaffold, photocrosslinkable hydrogel, poly(ethylene glycol) diacrylate (PEG-DA), stereolithography, visible light type II photoinitiator}, issn = {1937-3341}, doi = {10.1089/ten.tea.2019.0282},}, author = {Yang, Xin and Mohseni, Mina and Bas, Onur and Meinert, Christoph and New, Elizabeth J. and Castro, Nathan J.} } @article { ISI:000560967100009, title = {Unitary Subharmonic Response and Floquet Majorana Modes}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {8}, year = {2020}, month = {AUG 20}, pages = {086804}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Detection and manipulation of excitations with non-Abelian statistics, such as Majorana fermions, are essential for creating topological quantum computers. To this end, we show the connection between the existence of such localized particles and the phenomenon of unitary subharmonic response (SR) in periodically driven systems. In particular, starting from highly nonequilibrium initial states, the unpaired Majorana modes exhibit spin oscillations with twice the driving period, are localized, and can have exponentially long lifetimes in clean systems. While the lifetime of SR is limited in translationally invariant systems, we show that disorder can be engineered to stabilize the subharmonic response of Majorana modes. A viable observation of this phenomenon can be achieved using modern multiqubit hardware, such as superconducting circuits and cold atomic systems.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.086804}, author = {Shtanko, Oles and Movassagh, Ramis} } @article {lu_universal_2020, title = {Universal frequency engineering tool for microcavity nonlinear optics: multiple selective mode splitting of whispering-gallery resonances}, journal = {Photonics Res.}, volume = {8}, number = {11}, year = {2020}, note = {Place: PO BOX 800-211, SHANGHAI, 201800, PEOPLES R CHINA Publisher: CHINESE LASER PRESS Type: Article}, month = {nov}, pages = {1676{\textendash}1686}, abstract = {Whispering-gallery microcavities have been used to realize a variety of efficient parametric nonlinear optical processes through the enhanced light-matter interaction brought about by supporting multiple high quality factor and small modal volume resonances. Critical to such studies is the ability to control the relative frequencies of the cavity modes, so that frequency matching is achieved to satisfy energy conservation. Typically this is done by tailoring the resonator cross section. Doing so modifies the frequencies of all of the cavity modes, that is, the global dispersion profile, which may be undesired, for example, in introducing competing nonlinear processes. Here, we demonstrate a frequency engineering tool, termed multiple selective mode splitting (MSMS), that is independent of the global dispersion and instead allows targeted and independent control of the frequencies of multiple cavity modes. In particular, we show controllable frequency shifts up to 0.8 nm, independent control of the splitting of up to five cavity modes with optical quality factors {\textgreater}= 10(5), and strongly suppressed frequency shifts for untargeted modes. The MSMS technique can be broadly applied to a wide variety of nonlinear optical processes across different material platforms and can be used to both selectively enhance processes of interest and suppress competing unwanted processes.}, issn = {2327-9125}, doi = {10.1364/PRJ.401755}, author = {Lu, Xiyuan and Rao, Ashutosh and Moille, Gregory and Westly, Daron A. and Srinivasan, Kartik} } @article {16951, title = {Universal Logical Gates on Topologically Encoded Qubits via Constant-Depth Unitary Circuits}, journal = {Phys. Rev. Lett.}, volume = {125}, year = {2020}, month = {Jul}, pages = {050502}, doi = {10.1103/PhysRevLett.125.050502}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.125.050502}, author = {Zhu, Guanyu and Lavasani, Ali and Barkeshli, Maissam} } @article { ISI:000563710400004, title = {Universal nonequilibrium I-V curve near the two-channel Kondo-Luttinger quantum critical point}, journal = {Phys. Rev. B}, volume = {102}, number = {7}, year = {2020}, month = {AUG 28}, pages = {075145}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Over recent decades, a growing number of systems, many of them quantum critical, have been shown to exhibit non-Fermi-liquid behavior, but a full analytic understanding of such systems out of equilibrium is still lacking. In this paper, we provide a distinct example with broad applications in correlated mesoscopic systems to two-channel Kondo-Luttinger model where a Kondo impurity couples to two voltage-biased interacting electron leads, experimentally realizable in a dissipative quantum dot. Therein, an exotic quantum phase transition has been known to exist since the 1990s from the one-channel to two-channel Kondo ground states by enhancing electron interactions in the leads, but a controlled analytic approach to this quantum critical point has not yet been established due to the breakdown of weak-coupling perturbation theory near this strong-coupling critical point. We present a controlled method to this long-standing problem by mapping the system in the strong-coupling regime to an effective spin-boson-fermion Hamiltonian. Another type of non-Fermi-liquid quantum critical point is discovered with a distinct logarithmic-in-temperature and -voltage dependence in transport. We further obtain an analytical form for the universal differential conductance out of equilibrium near the transition. Our approach can be further generalized to study nonequilibrium physics of other strong-coupling low-dimensional non-Fermi-liquid fixed points. The relevance of our results for recent experiments is discussed.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.075145}, author = {Lin, C-Y and Chang, Y-Y and Rylands, C. and Andrei, N. and Chung, C-H} } @article { ISI:000558086800008, title = {Viscous Properties of a Degenerate One-Dimensional Fermi Gas}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {7}, year = {2020}, month = {AUG 11}, pages = {076601}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study the viscous properties of a system of weakly interacting spin-1/2 fermions in one dimension. Accounting for the effect of interactions on the quasiparticle energy spectrum, we obtain the bulk viscosity of this system at low temperatures. Our result is valid for frequencies that are small compared with the rate of fermion backscattering. For frequencies larger than this exponentially small rate, the excitations of the system become decoupled from the center of mass motion, and the fluid is described by two-fluid hydrodynamics. We calculate the three transport coefficients required to describe viscous dissipation in this regime.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.076601}, author = {DeGottardi, Wade and Matveev, K. A.} } @article {balram_zn_2020, title = {Z(n) superconductivity of composite bosons and the 7/3 fractional quantum {Hall} effect}, journal = {Phys. Rev. Res.}, volume = {2}, number = {1}, year = {2020}, note = {Place: ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA Publisher: AMER PHYSICAL SOC Type: Article}, month = {mar}, abstract = {The topological p-wave pairing of composite fermions, believed to be responsible for the 5/2 fractional quantum Hall effect (FQHE), has generated much exciting physics. Motivated by the parton theory of the FQHE, we consider the possibility of a new kind of emergent {\textquotedblleft}superconductivity{\textquotedblright} in the 1/3 FQHE, which involves condensation of clusters of n composite bosons. From a microscopic perspective, the state is described by the n (n) over bar 111 parton wave function P-LLL Phi(n)Phi(n)*Phi(3)(1), where Phi(n) is the wave function of the integer quantum Hall state with n filled Landau levels and P-LLL is the lowest-Landau-level projection operator. It represents a Z(n) superconductor of composite bosons, because the factor Phi(3)(1) similar to Pi(j{\textless}k) (z(j) - z(k))(3), where z(j) = x(j) - iy(j) is the coordinate of the jth electron, binds three vortices to electrons to convert them into composite bosons, which then condense into the Z(n) superconducting state vertical bar Phi(n)vertical bar(2). From a field theoretical perspective, this state can be understood by starting with the usual Laughlin theory and gauging a Z(n) subgroup of the U(1) charge conservation symmetry. We find from detailed quantitative calculations that the 2{\textless}(2)over bar{\textgreater}111 and 3 (3) over bar 111 states are at least as plausible as the Laughlin wave function for the exact Coulomb ground state at filling nu = 7/3, suggesting that this physics is possibly relevant for the 7/3 FQHE. The Z(n) order leads to several observable consequences, including quasiparticles with fractionally quantized charges of magnitude e/(3n) and the existence of multiple neutral collective modes. It is interesting that the FQHE may be a promising venue for the realization of exotic Z(n) superconductivity.}, doi = {10.1103/PhysRevResearch.2.013349}, author = {Balram, Ajit C. and Jain, J. K. and Barkeshli, Maissam} } @article { ISI:000501768100003, title = {Additive biomanufacturing of scaffolds for breast reconstruction}, journal = {Addit. Manuf.}, volume = {30}, year = {2019}, month = {DEC}, pages = {UNSP 100845}, publisher = {ELSEVIER}, type = {Article}, abstract = {Limitations for the current clinical treatment strategies for breast reconstruction have prompted researchers and bioengineers to develop unique techniques based on tissue engineering and regenerative medicine (TE\&RM) principles. Recently, scaffold-guided soft TE has emerged as a promising approach due to its potential to modulate the process of tissue regeneration. Herein, we utilized additive biomanufacturing (ABM) to develop an original design-based concept for scaffolds which can be applied in TE-based breast reconstruction procedures. The scaffold design addresses biomechanical and biological requirements for medium to large-volume regeneration with the potential of customization. The model is composed of two independent structural components. The external structure provides biomechanical stability to minimize load transduction to the newly formed tissue while the internal structure provides a large pore and fully interconnected pore architecture to facilitate tissue regeneration. A methodology was established to design, optimize and 3D print the external structure with customized biomechanical properties. The internal structure was also designed and printed with a gradient of pore size and a channel structure to facilitate lipoaspirated fat delivery and entrapment. A fused filament fabrication-based printing strategy was employed to print two structures as a monolithic breast implant.}, keywords = {Additive biomanufacturing, Breast implant customization, In silico modelling, Scaffolds}, issn = {2214-8604}, doi = {10.1016/j.addma.2019.100845}, author = {Mohseni, Mina and Bas, Onur and Castro, Nathan J. and Schmutz, Beat and Hutmacher, Dietmar W.} } @article {13366, title = {Alignment-dependent decay rate of an atomic dipole near an optical nanofiber}, journal = {Phys. Rev. A}, volume = {99}, year = {2019}, month = {Jan}, pages = {013822}, doi = {10.1103/PhysRevA.99.013822}, url = {https://link.aps.org/doi/10.1103/PhysRevA.99.013822}, author = {Solano, P. and Grover, J. A. and Xu, Y. and Barberis-Blostein, P. and Munday, J. N. and Orozco, L. A. and Phillips, W. D. and Rolston, S. L.} } @article {ISI:000480388400001, title = {Almost linear Haldane pseudopotentials and emergent conformal block wave functions in a Landau level}, journal = {Phys. Rev. B}, volume = {100}, number = {7}, year = {2019}, month = {AUG 12}, pages = {075122}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We consider a two-dimensional model of particles interacting in a Landau level. We work in a finite disk geometry and take the particles to interact with a linearly decreasing two-body Haldane pseudopotential. We show that the ground-state subspace of this model is spanned by the wave functions that can be written as polynomial conformal blocks (of an arbitrary conformal field theory) consistent with the filling fraction (scaling dimension). To remove degeneracies, we then add a quadratic perturbation to the Hamiltonian and show that (1) conformal blocks constructed using the Moore-Read construction (e.g., Laughlin, Pfaffian, and Read-Rezayi states) remain exact eigenstates of this model in the thermodynamic limit, and (2) by tuning an externally imposed single-body -L-z(2) potential we can enforce Moore-Read conformal blocks to become exact ground states of this model in the thermodynamic limit. We cannot rule out the possibility of residual degeneracies in this limit. This model has no filling dependence and is comprised only from two-body long-range interactions and external single-body potentials. Our results provide insight into how conformal block wave functions can emerge in a Landau level.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.075122}, author = {Alavirad, Yahya} } @article {ISI:000457706700026, title = {Anomalous Low-Temperature Enhancement of Supercurrent in Topological-Insulator Nanoribbon Josephson Junctions: Evidence for Low-Energy Andreev Bound States}, journal = {Phys. Rev. Lett.}, volume = {122}, number = {4}, year = {2019}, month = {FEB 1}, pages = {047003}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We report anomalous enhancement of the critical current at low temperatures in gate-tunable Josephson junctions made from topological insulator BiSbTeSe2 nanoribbons with superconducting Nb electrodes. In contrast to conventional junctions, as a function of the decreasing temperature T, the increasing critical current I-c exhibits a sharp upturn at a temperature T-{*} around 20\% of the junction critical temperature for several different samples and various gate voltages. The I-c vs T demonstrates a short junction behavior for T > T-{*}, but crosses over to a long junction behavior for T < T-{*} with an exponential T dependence I-c proportional to exp(-k(B)T/delta), where k(B) is the Boltzmann constant. The extracted characteristic energy scale delta is found to be an order of magnitude smaller than the induced superconducting gap of the junction. We attribute the long-junction behavior with such a small delta to low-energy Andreev bound states arising from winding of the electronic wave function around the circumference of the topological insulator nanoribbon.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.122.047003}, author = {Kayyalha, Morteza and Kargarian, Mehdi and Kazakov, Aleksandr and Miotkowski, Ireneusz and Galitski, Victor M. and Yakovenko, Victor M. and Rokhinson, Leonid P. and Chen, Yong P.} } @article { ISI:000454906800010, title = {Artificial gauge fields with ultracold atoms}, journal = {PHYSICS TODAY}, volume = {72}, number = {1}, year = {2019}, month = {JAN}, pages = {39-44}, issn = {0031-9228}, doi = {10.1063/PT.3.4111}, author = {Galitski, Victor and Juzeliunas, Gediminas and Ian B Spielman} } @article { ISI:000488203600027, title = {Atypical quantized resistances in millimeter-scale epitaxial graphene p-n junctions}, journal = {Carbon}, volume = {154}, year = {2019}, month = {DEC}, pages = {230-237}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, abstract = {We have demonstrated the millimeter-scale fabrication of monolayer epitaxial graphene p-n junction devices using simple ultraviolet photolithography, thereby significantly reducing device processing time compared to that of electron beam lithography typically used for obtaining sharp junctions. This work presents measurements yielding nonconventional, fractional multiples of the typical quantized Hall resistance at nu = 2 (R-H approximate to 12906 Omega) that take the form: a/bR(H). Here, a and b have been observed to take on values such 1, 2, 3, and 5 to form various coefficients of R-H. Additionally, we provide a framework for exploring future device configurations using the LTspice circuit simulator as a guide to understand the abundance of available fractions one may be able to measure. These results support the potential for drastically simplifying device processing time and may be used for many other two-dimensional materials. Published by Elsevier Ltd.}, issn = {0008-6223}, doi = {10.1016/j.carbon.2019.08.002}, author = {Rigosi, Albert E. and Patel, Dinesh and Marzano, Martina and Kruskopf, Mattias and Hill, Heather M. and Jin, Hanbyul and Hu, Jiuning and Walker, Angela R. Hight and Ortolano, Massimo and Callegaro, Luca and Liang, Chi-Te and Newell, David B.} } @conference {ISI:000482088000005, title = {Auger recombination-induced neutralization and stretched exponential recharging in an InAs quantum dot}, booktitle = {QUANTUM DOTS AND NANOSTRUCTURES: GROWTH, CHARACTERIZATION, AND MODELING XVI}, series = {Proceedings of SPIE}, volume = {10929}, year = {2019}, note = {Conference on Quantum Dots and Nanostructures: Growth, Characterization, and Modeling XVI, San Francisco, CA, FEB 06-07, 2019}, pages = {109290F}, publisher = {SPIE}, organization = {SPIE}, type = {Proceedings Paper}, abstract = {We investigate the charging dynamics in epitaxially grown InAs quantum dots (QDs) under resonant excitation with and without additional low-power above-band excitation. Time-resolved resonance fluorescence from a charged exciton (trion) transition is recorded as the above-band excitation is modulated on and off. The fluorescence intensity varies as the QD changes from charged to neutral and back due to the influence of the above-band excitation. We fit the transients of the decay of the time-resolved resonance fluorescence after the above-band excitation turns off with a model that represents the neutralization process. The time dependence of the transients indicate that Auger recombination of resonantly excited trions is largely responsible for neutralization of the charged state when the above-band excitation is off. Additionally, a stretched exponential component of the transient of the fluorescence decay indicates the QD is supplied with charges via carrier migration through a stochastic collection of weakly-binding sites, resulting in sub-diffusion-like dynamics.}, keywords = {anomalous diffusion, Auger recombination, charge carrier dynamics, quantum dot, resonance fluorescence, stretched exponential, time-resolved, trion}, isbn = {978-1-5106-2501-3}, issn = {0277-786X}, doi = {10.1117/12.2506555}, author = {Lander, Gary R. and Isaac, Samantha D. and Chen, Disheng and Demircan, Samet and Solomon, Glenn S. and Flagg, Edward B.}, editor = {Huffaker, DL and Eisele, H} } @article {ISI:000462066300003, title = {Bell{\textquoteright}s inequality, generalized concurrence and entanglement in qubits}, journal = {Int. J. Mod. Phys. A}, volume = {34}, number = {6-7}, year = {2019}, month = {MAR 10}, pages = {1950032}, publisher = {WORLD SCIENTIFIC PUBL CO PTE LTD}, type = {Article}, abstract = {It is well known that the maximal violation of the Bell{\textquoteright}s inequality for a two-qubit system is related to the entanglement formation in terms of a concurrence. However, a generalization of this relation to an n-qubit state has not been found. In this paper, we demonstrate some extensions of the relation between the upper bound of the Bell{\textquoteright}s violation and a generalized concurrence in several n-qubit states. In particular, we show the upper bound of the Bell{\textquoteright}s violation can be expressed as a function of the generalized concurrence, if a state can be expressed in terms of two variables. We apply the relation to the Wen-Plaquette model and show that the topological entanglement entropy can be extracted from the maximal Bell{\textquoteright}s violation.}, keywords = {Bell{\textquoteright}s inequality, entanglement, generalized concurrence, QUBIT}, issn = {0217-751X}, doi = {10.1142/S0217751X19500325}, author = {Chang, Po-Yao and Chu, Su-Kuan and Ma, Chen-Te} } @article { ISI:000500475200001, title = {Benchmarking an 11-qubit quantum computer}, journal = {Nat. Commun.}, volume = {10}, year = {2019}, month = {NOV 29}, pages = {5464}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {The field of quantum computing has grown from concept to demonstration devices over the past 20 years. Universal quantum computing offers efficiency in approaching problems of scientific and commercial interest, such as factoring large numbers, searching databases, simulating intractable models from quantum physics, and optimizing complex cost functions. Here, we present an 11-qubit fully-connected, programmable quantum computer in a trapped ion system composed of 13 Yb-171(+) ions. We demonstrate average single-qubit gate fidelities of 99.5\%, average two-qubit-gate fidelities of 97.5\%, and SPAM errors of 0.7\%. To illustrate the capabilities of this universal platform and provide a basis for comparison with similarly-sized devices, we compile the Bernstein-Vazirani and Hidden Shift algorithms into our native gates and execute them on the hardware with average success rates of 78\% and 35\%, respectively. These algorithms serve as excellent benchmarks for any type of quantum hardware, and show that our system outperforms all other currently available hardware.}, issn = {2041-1723}, doi = {10.1038/s41467-019-13534-2}, author = {Wright, K. and Beck, K. M. and Debnath, S. and Amini, J. M. and Nam, Y. and Grzesiak, N. and Chen, J. -S. and Pisenti, N. C. and Chmielewski, M. and Collins, C. and Hudek, K. M. and Mizrahi, J. and Wong-Campos, J. D. and Allen, S. and Apisdorf, J. and Solomon, P. and Williams, M. and Ducore, A. M. and Blinov, A. and Kreikemeier, S. M. and Chaplin, V. and Keesan, M. and Monroe, C. and Kim, J.} } @article {ISI:000461964300002, title = {Braiding and gapped boundaries in fracton topological phases}, journal = {Phys. Rev. B}, volume = {99}, number = {12}, year = {2019}, month = {MAR 19}, pages = {125132}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study gapped boundaries of Abelian type-I fracton systems in three spatial dimensions. Using the X-cube model as our motivating example, we give a conjecture, with partial proof, of the conditions for a boundary to be gapped. In order to state our conjecture, we use a precise definition of fracton braiding and show that bulk braiding of fractons has several features that make it insufficient to classify gapped boundaries. Most notable among these is that bulk braiding is sensitive to geometry and is {\textquoteleft}{\textquoteleft}nonreciprocal{{\textquoteright}{\textquoteright}}; that is, braiding an excitation a around b need not yield the same phase as braiding b around a. Instead, we define fractonic {\textquoteleft}{\textquoteleft}boundary braiding,{{\textquoteright}{\textquoteright}} which resolves these difficulties in the presence of a boundary. We then conjecture that a boundary of an Abelian fracton system is gapped if and only if a {\textquoteleft}{\textquoteleft}boundary Lagrangian subgroup{{\textquoteright}{\textquoteright}} of excitations is condensed at the boundary; this is a generalization of the condition for a gapped boundary in two spatial dimensions, but it relies on boundary braiding instead of bulk braiding. We also discuss the distinctness of gapped boundaries and transitions between different topological orders on gapped boundaries.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.125132}, author = {Bulmash, Daniel and Iadecola, Thomas} } @conference {ISI:000482226303019, title = {Bright Beams of Intensity Difference Squeezed Light for use in Sub-shot-noise Imaging}, booktitle = {2019 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO)}, series = {Conference on Lasers and Electro-Optics}, year = {2019}, note = {Conference on Lasers and Electro-Optics (CLEO), San Jose, CA, MAY 05-10, 2019}, publisher = {IEEE; AdValue Photon; Amer Elements; Class5 Photon; Coherent; GoFoton; Light Convers; LightTrans; MKS; OZ Opt Online; Santec; ThorLabs; UQDevices; YSL Photon}, organization = {IEEE; AdValue Photon; Amer Elements; Class5 Photon; Coherent; GoFoton; Light Convers; LightTrans; MKS; OZ Opt Online; Santec; ThorLabs; UQDevices; YSL Photon}, type = {Proceedings Paper}, abstract = {We present a method for using bright beams of intensity difference squeezed light to perform sub-shot-noise imaging. The intensity correlated twin beams are generated by four wave mixing in rubidium vapour. (C) 2019 The Author(s)}, isbn = {978-1-943580-57-6}, issn = {2160-9020}, author = {Speirs, Rory W. and Brewer, Nicholas R. and Wu, Meng-Chang and Lett, Paul D.} } @article { ISI:000488503500029, title = {Broadband resonator-waveguide coupling for efficient extraction of octave-spanning microcombs}, journal = {Opt. Lett.}, volume = {44}, number = {19}, year = {2019}, month = {OCT 1}, pages = {4737-4740}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {Octave-spanning frequency combs have been successfully demonstrated in Kerr nonlinear microresonators. These microcombs rely on both engineered dispersion, to enable generation of frequency components across the octave, and on engineered coupling, to efficiently extract the generated light into an access waveguide while maintaining a close to critically coupled pump. The latter is challenging, as the spatial overlap between the access waveguide and the ring modes decays with frequency. This leads to strong coupling variation across the octave, with poor extraction at short wavelengths. Here, we investigate how a waveguide wrapped around a portion of the resonator, in a pulley scheme, can improve the extraction of octave-spanning microcombs, in particular at short wavelengths. We use the coupled-mode theory to predict the performance of the pulley couplers and demonstrate good agreement with experimental measurements. Using an optimal pulley coupling design, we demonstrate a 20 dB improvement in extraction at short wavelengths compared to straight waveguide coupling. (C) 2019 Optical Society of America}, issn = {0146-9592}, doi = {10.1364/OL.44.004737}, author = {Moille, Gregory and Li, Qing and Briles, Travis C. and Yu, Su-Peng and Drake, Tara and Lu, Xiyuan and Rao, Ashutosh and Westly, Daron and Papp, Scott B. and Srinivasan, Kartik} } @article {ISI:000473123700004, title = {Canonical forms for single-qutrit Clifford plus T operators}, journal = {Ann. Phys.}, volume = {406}, year = {2019}, month = {JUL}, pages = {54-70}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, type = {Article}, abstract = {We introduce canonical forms for single qutrit Clifford+T circuits and prove that every single-qutrit Clifford+T operator admits a unique such canonical form. We show that our canonical forms are T-optimal in the sense that among all the single-qutrit Clifford+T circuits implementing a given operator our canonical form uses the least number of T gates. Finally, we provide an algorithm which inputs the description of an operator (as a matrix or a circuit) and constructs the canonical form for this operator. The algorithm runs in time linear in the number of T gates. Our results provide a higher-dimensional generalization of prior work by Matsumoto and Amano who introduced similar canonical forms for single-qubit Clifford+T circuits. (C) 2019 Elsevier Inc. All rights reserved.}, keywords = {Quantum circuits, quantum computation, Qutrits, Universal gate sets}, issn = {0003-4916}, doi = {10.1016/j.aop.2019.04.001}, author = {Glaudell, Andrew N. and Ross, Neil J. and Taylor, Jacob M.} } @article {ISI:000466441100011, title = {Cavity Quantum Eliashberg Enhancement of Superconductivity}, journal = {Phys. Rev. Lett.}, volume = {122}, number = {16}, year = {2019}, month = {APR 26}, pages = {167002}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Driving a conventional superconductor with an appropriately tuned classical electromagnetic field can lead to an enhancement of superconductivity via a redistribution of the quasiparticles into a more favorable nonequilibrium distribution-a phenomenon known as the Eliashberg effect. Here, we theoretically consider coupling a two-dimensional superconducting film to the quantized electromagnetic modes of a microwave resonator cavity. As in the classical Eliashberg case, we use a kinetic equation to study the effect of the fluctuating, dynamical electromagnetic field on the Bogoliubov quasiparticles. We find that when the photon and quasiparticle systems are out of thermal equilibrium, a redistribution of quasiparticles into a more favorable nonequilibrium steady state occurs, thereby enhancing superconductivity in the sample. We predict that by tailoring the cavity environment (e.g., the photon occupation and spectral functions), enhancement can be observed in a variety of parameter regimes, offering a large degree of tunability.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.122.167002}, author = {Curtis, Jonathan B. and Raines, Zachary M. and Allocca, Andrew A. and Hafezi, Mohammad and Galitski, Victor M.} } @article {ISI:000455821100001, title = {Cavity superconductor-polaritons}, journal = {Phys. Rev. B}, volume = {99}, number = {2}, year = {2019}, month = {JAN 14}, pages = {020504}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Following the recent success of realizing exciton-polariton condensates in cavities, we examine the hybridization of cavity photons with the closest analog of excitons within a superconductor, states called Bardasis-Schrieffer modes. Although these modes do not typically couple linearly to light, one can engineer a coupling with an externally imposed supercurrent, leading to the formation of hybridized Bardasis-Schrieffer-polariton states, which we obtain both as poles of the bosonic Green{\textquoteright}s function and through the derivation of an effective Hamiltonian picture for the model. These new excitations have nontrivial overlap with both the original photon states and d-wave superconducting fluctuations. We conjecture that a phase-coherent density of these objects could produce a finite d-wave component of the superconducting order parameter-an s +/- id superconducting state.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.020504}, author = {Allocca, Andrew A. and Raines, Zachary M. and Curtis, Jonathan B. and Galitski, Victor M.} } @article {ISI:000476652500107, title = {Chiral light-matter interactions using spin-valley states in transition metal dichalcogenides}, journal = {Opt. Express}, volume = {27}, number = {15}, year = {2019}, month = {JUL 22}, pages = {21367-21379}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {Chiral light-matter interactions can enable polarization to control the direction of light emission in a photonic device. Most realizations of chiral light-matter interactions require external magnetic fields to break time-reversal symmetry of the emitter. One way to eliminate this requirement is to utilize strong spin-orbit coupling present in transition metal dichalcogenides that exhibit a valley-dependent polarized emission. Such interactions were previously reported using plasmonic waveguides, but these structures exhibit short propagation lengths due to loss. Chiral dielectric structures exhibit much lower loss levels and could therefore solve this problem. We demonstrate chiral light-matter interactions using spin-valley states of transition metal dichalcogenide monolayers coupled to a dielectric waveguide. We use a photonic crystal glide-plane waveguide that exhibits chiral modes with high field intensity, coupled to monolayer WSe2. We show that the circularly polarized emission of the monolayer preferentially couples to one direction of the waveguide, with a directionality as high as 0.35, limited by the polarization purity of the bare monolayer emission. This system enables on-chip directional control of light and could provide new ways to control spin and valley degrees of freedom in a scalable photonic platform. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {1094-4087}, doi = {10.1364/OE.27.021367}, author = {Yang, Zhili and Aghaeimeibodi, Shahriar and Waks, Edo} } @article {ISI:000475514100001, title = {Cold hybrid ion-atom systems}, journal = {Rev. Mod. Phys.}, volume = {91}, number = {3}, year = {2019}, month = {JUL 15}, pages = {035001}, publisher = {AMER PHYSICAL SOC}, type = {Review}, abstract = {Hybrid systems of laser-cooled trapped ions and ultracold atoms combined in a single experimental setup have recently emerged as a new platform for fundamental research in quantum physics. This paper reviews the theoretical and experimental progress in research on cold hybrid ion-atom systems which aim to combine the best features of the two well-established fields. A broad overview is provided of the theoretical description of ion-atom mixtures and their applications, and a report is given on advances in experiments with ions trapped in Paul or dipole traps overlapped with a cloud of cold atoms, and with ions directly produced in a Bose-Einstein condensate. This review begins with microscopic models describing the electronic structure, interactions, and collisional physics of ion-atom systems at low and ultralow temperatures, including radiative and nonradiative charge-transfer processes and their control with magnetically tunable Feshbach resonances. Then the relevant experimental techniques and the intrinsic properties of hybrid systems are described. In particular, the impact is discussed of the micromotion of ions in Paul traps on ion-atom hybrid systems. Next, a review of recent proposals is given for using ions immersed in ultracold gases for studying cold collisions, chemistry, many-body physics, quantum simulation, and quantum computation and their experimental realizations. The last part focuses on the formation of molecular ions via spontaneous radiative association, photoassociation, magnetoassociation, and sympathetic cooling. Applications and prospects are discussed of cold molecular ions for cold controlled chemistry and precision spectroscopy.}, issn = {0034-6861}, doi = {10.1103/RevModPhys.91.035001}, author = {Tomza, Michal and Jachymski, Krzysztof and Gerritsma, Rene and Negretti, Antonio and Calarco, Tommaso and Idziaszek, Zbigniew and Julienne, Paul S.} } @article {ISI:000456032500004, title = {Conditions allowing error correction in driven qubits}, journal = {Phys. Rev. B}, volume = {99}, number = {4}, year = {2019}, month = {JAN 17}, pages = {045422}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We consider a qubit that is driven along its logical z axis, with noise along the z axis in the driving field Omega proportional to some function f (Omega), as well as noise along the logical x axis. We establish that whether or not errors due to both types of noise can be canceled out, even approximately, depends on the explicit functional form of f (Omega) by considering a power-law form, f (Omega) proportional to Omega(k). In particular, we show that such cancellation is impossible for k = 0, 1, or any even integer. However, any other odd integer value of k besides 1 does permit cancellation; in fact, we show that both types of errors can be corrected with a sequence of four square pulses of equal duration. We provide sets of parameters that correct for errors for various rotations and evaluate the error, measured by the infidelity, for the corrected rotations versus the naive rotations, i.e., the operations that, in the complete absence of noise, would produce the desired rotations (in this case a single pulse of appropriate duration and magnitude). We also consider a train of four trapezoidal pulses, which take into account the fact that there will be, in real experimental systems, a finite rise time, again providing parameters for error-corrected rotations that employ such pulse sequences. Our dynamical decoupling error correction scheme works for any qubit platform as long as the errors are quasistatic.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.045422}, author = {Throckmorton, Robert E. and S. Das Sarma} } @article {ISI:000456301900009, title = {Conductance smearing and anisotropic suppression of induced superconductivity in a Majorana nanowire}, journal = {Phys. Rev. B}, volume = {99}, number = {2}, year = {2019}, month = {JAN 22}, pages = {024510}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {In a recent high-quality experimental work on normal metal-superconducting nanowire junctions (J. D. S. Bommer et al., arXiv :1807.01940), strong anisotropic suppression of induced superconductivity has been observed in tunnel conductance measurements in the presence of applied magnetic field with variable orientation. Following this finding, we investigate theoretically the dependence of tunnel conductance on the direction of the Zeeman field in order to understand the operational mechanisms and to extract effective system parameters. Second, motivated by a generic discrepancy between experiment and theory, i.e., many in-gap and above-gap conductance features predicted by theory are barely observed in experiments, we study several mechanisms possibly responsible for the suppression of the theoretically predicted conductance features (e.g., length of the nanowire, self-energy effect due to the proximity effect, finite temperature, finite dissipation, and multiband effect). One essential finding in the current work is that only by a combined understanding of both suppression mechanisms can we extract effective system parameters from the experimental data (e.g., the effective nanowire-superconductor coupling, the effective Lande g factor, and the chemical potential of the semiconducting nanowire). In addition, we consider topologically trivial Andreev bound states in hybrid nanowires in the presence of potential inhomogeneities, such as external quantum dots or potential inhomogeneities inside the nanowire. We compare the anisotropic, field-dependent features induced by these nontopological Andreev bound states with the corresponding features produced by topological Majorana zero modes in pristine nanostructures, so that we can provide guidance to differentiate between the topologically trivial and nontrivial cases.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.024510}, author = {Liu, Chun-Xiao and Sau, Jay D. and Stanescu, Tudor D. and S. Das Sarma} } @article {ISI:000464756500001, title = {Confined Quasiparticle Dynamics in Long-Range Interacting Quantum Spin Chains}, journal = {Phys. Rev. Lett.}, volume = {122}, number = {15}, year = {2019}, month = {APR 16}, pages = {150601}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study the quasiparticle excitation and quench dynamics of the one-dimensional transverse-field Ising model with power-law (1/r(alpha)) interactions. We find that long-range interactions give rise to a confining potential, which couples pairs of domain walls (kinks) into bound quasiparticles, analogous to mesonic states in high-energy physics. We show that these quasiparticles have signatures in the dynamics of order parameters following a global quench, and the Fourier spectrum of these order parameters can be exploited as a direct probe of the masses of the confined quasiparticles. We introduce a two-kink model to qualitatively explain the phenomenon of long-range-interaction-induced confinement and to quantitatively predict the masses of the bound quasiparticles. Furthermore, we illustrate that these quasiparticle states can lead to slow thermalization of one-point observables for certain initial states. Our work is readily applicable to current trapped-ion experiments.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.122.150601}, author = {Liu, Fangli and Lundgren, Rex and Titum, Paraj and Pagano, Guido and Zhang, Jiehang and Monroe, Christopher and Gorshkov, V, Alexey} } @article { ISI:000504862300005, title = {Coupled electron-impurity and electron-phonon systems as trivial non-Fermi liquids}, journal = {Phys. Rev. B}, volume = {100}, number = {23}, year = {2019}, month = {DEC 30}, pages = {235149}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We consider an electron gas, both in two (2D) and three (3D) dimensions, interacting with quenched impurities and phonons within leading order finite-temperature many-body perturbation theories, calculating the electron self-energies, spectral functions, and momentum distribution functions at finite temperatures. The resultant spectral function is in general highly non-Lorentzian, indicating that the system is not a Fermi liquid in the usual sense. The calculated momentum distribution function cannot be approximated by a Fermi function at any temperature, providing a rather simple example of a non-Fermi liquid with well-understood properties.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.235149}, author = {Buterakos, Donovan and Das Sarma, Sankar} } @article {ISI:000478991700001, title = {Critical viscosity of a fluctuating superconductor}, journal = {Phys. Rev. B}, volume = {100}, number = {6}, year = {2019}, month = {AUG 2}, pages = {060501}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We consider a fluctuating superconductor in the vicinity of the transition temperature, T-c. The fluctuation shear viscosity is calculated. In two dimensions, the leading correction to viscosity is negative and scales as delta eta(T) alpha ln(T - T-c). Critical hydrodynamics of the fluctuating superconductor involves two fluids: a fluid of fluctuating pairs and a quasiparticle fluid of single-electron excitations. The pair viscosity (Aslamazov-Larkin) term is shown to be zero. The (density of states) correction to viscosity of single-electron excitations is negative, which is due to fluctuating pairing that results in a reduction of electron density. Scattering of electrons off of the fluctuations gives rise to an enhanced quasiparticle scattering and another (Maki-Thomson) negative correction to viscosity. Our results suggest that fluctuating superconductors provide a promising platform to investigate low-viscosity electronic media and may potentially host fermionic/electronic turbulence. Some experimental probes of two-fluid critical hydrodynamics are proposed such as time-of-flight measurement of turbulent energy cascades in critical cold atom superfluids and magnetic dynamos in three-dimensional fluctuating superconductors.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.060501}, author = {Liao, Yunxiang and Galitski, Victor} } @article { ISI:000447062400001, title = {Cryogenic trapped-ion system for large scale quantum simulation}, journal = {QUANTUM SCIENCE AND TECHNOLOGY}, volume = {4}, number = {1}, year = {2019}, month = {JAN}, pages = {UNSP 014004}, issn = {2058-9565}, doi = {10.1088/2058-9565/aae0fe}, author = {Pagano, G. and Hess, P. W. and Kaplan, H. B. and Tan, W. L. and Richerme, P. and Becker, P. and Kyprianidis, A. and Zhang, J. and Birckelbaw, E. and Hernandez, M. R. and Wu, Y. and Monroe, C.} } @article {ISI:000458854900004, title = {Curvature of gap closing features and the extraction of Majorana nanowire parameters}, journal = {Phys. Rev. B}, volume = {99}, number = {5}, year = {2019}, month = {FEB 15}, pages = {054507}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Recent tunneling conductance measurements of Majorana nanowires show a strong variation in the magnetic-field dependence of the superconducting gap among different devices. Here, we theoretically study the magnetic field dependence of the gap closing feature and establish that the degree of convexity (or concavity) of the gap closing as a function of Zeeman field can provide critical constraints on the underlying microscopic parameters of the semiconductor-superconductor hybrid system model. Specifically, we show that the gap closing feature is entirely concave only for strong spin-orbit coupling strength relative to the chemical potential. Additionally, the nonlinearity (i.e., concavity or convexity) of the gap closing as a function of magnetic field complicates the simple assignment of a constant effective g-factor to the states in the Majorana nanowire. We develop a procedure to estimate the effective g-factor from recent experimental data that accounts for the nonlinear gap closing, resulting from the interplay between chemical potential and spin-orbit coupling. Thus, measurements of the magnetic field dependence of the gap closure on the trivial side of the topological quantum phase transition can provide useful information on parameters that are critical to the theoretical modeling of Majorana nanowires.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.054507}, author = {Pan, Haining and Sau, Jay D. and Stanescu, Tudor D. and S. Das Sarma} } @article { ISI:000491132700014, title = {Demonstration of slow light in rubidium vapor using single photons from a trapped ion}, journal = {Sci. Adv.}, volume = {5}, number = {10}, year = {2019}, month = {OCT}, pages = {eaav4651}, publisher = {AMER ASSOC ADVANCEMENT SCIENCE}, type = {Article}, abstract = {Practical implementation of quantum networks is likely to interface different types of quantum systems. Photonically linked hybrid systems, combining unique properties of each constituent system, have typically required sources with the same photon emission wavelength. Trapped ions and neutral atoms both have compelling properties as nodes and memories in a quantum network but have never been photonically linked because of vastly different operating wavelengths. Here, we demonstrate the first interaction between neutral atoms and photons emitted from a single trapped ion. We use slow light in Rb-87 vapor to delay photons originating from a trapped Ba-138(+) ion by up to 13.5 +/- 0.5 ns, using quantum frequency conversion to overcome the frequency difference between the ion and neutral atoms. The delay is tunable and preserves the temporal profile of the photons. This result showcases a hybrid photonic interface usable as a synchronization tool-a critical component in any future large-scale quantum network.}, issn = {2375-2548}, doi = {10.1126/sciadv.aav4651}, author = {Siverns, J. D. and Hannegan, J. and Quraishi, Q.} } @conference {ISI:000484886200007, title = {Design and performance study of actively holding-off GHz-gated InGaAs/InP SPADs}, booktitle = {ADVANCED PHOTON COUNTING TECHNIQUES XIII}, series = {Proceedings of SPIE}, volume = {10978}, year = {2019}, note = {Conference on Advanced Photon Counting Techniques XIII, Baltimore, MD, APR 17-18, 2019}, pages = {109780C}, publisher = {SPIE}, organization = {SPIE}, type = {Proceedings Paper}, abstract = {High-speed periodic gating of InGaAs/InP single-photon avalanche diodes (SPADs) has allowed these detectors to operate at count rates above 108 per second with low afterpulsing. However, a drawback of high-speed periodic gating is that bias gates are applied continuously, regardless of whether an avalanche has occurred or not. This is disadvantageous because gates immediately following an avalanche have elevated afterpulse probabilities, and the additional charge from these secondary events contributes to the overall afterpulse probability. We investigate this phenomenon in a proof-of-principle experiment in which the series of bias gates is briefly interrupted after an avalanche, and we measure the resulting impact on the afterpulse probability. We observe a significant reduction in afterpulsing when such a bias-gate hold-off is applied to an InGaAs/InP SPAD gated at 1.25 GHz; when one bias gate is omitted after an avalanche the per-gate afterpulse probability is reduced by more than 40 \%. These results indicate that afterpulsing noise at high count rates can be further reduced in high-speed-gated SPADs.}, keywords = {afterpulsing, photon detection, quantum communication, single-photon avalanche diode, Single-photon detector}, isbn = {978-1-5106-2622-5}, issn = {0277-786X}, doi = {10.1117/12.2520620}, author = {Restelli, Alessandro and Bienfang, Joshua C. and Migdall, Alan L.}, editor = {Itzler, MA and Bienfang, JC and McIntosh, KA} } @article {ISI:000461830900002, title = {Development of transmon qubits solely from optical lithography on 300 mm wafers}, journal = {Quantum Sci. Technol.}, volume = {4}, number = {2}, year = {2019}, month = {APR}, pages = {025012}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {Qubit information processors are increasing in footprint but currently rely on e-beam lithography for patterning the required Josephson junctions (JJs). Advanced optical lithography is an alternative patterning method, and we report on the development of transmon qubits patterned solely with optical lithography. The lithography uses 193 nm wavelength exposure and 300 mm large silicon wafers. Qubits and arrays of evaluation JJs were patterned with process control which resulted in narrow feature distributions: a standard deviation of 0.78\% for a 220 nm linewidth pattern realized across over half the width of the wafers. Room temperature evaluation found a 2.8\%-3.6\% standard deviation in JJ resistance in completed chips. The qubits used aluminum and titanium nitride films on silicon substrates without substantial silicon etching. T-1 times of the qubits were extracted at 26-27 mu s, indicating a low level of material-based qubit defects. This study shows that large wafer optical lithography on silicon is adequate for high-quality transmon qubits, and shows a promising path for improving many-qubit processors.}, keywords = {fabrication, large wafer, QUBIT, silicon, superconducting}, issn = {2058-9565}, doi = {10.1088/2058-9565/ab0ca8}, author = {Foroozani, N. and Hobbs, C. and Hung, C. C. and Olson, S. and Ashworth, D. and Holland, E. and Malloy, M. and Kearney, P. and O{\textquoteright}Brien, B. and Bunday, B. and DiPaola, D. and Advocate, W. and Murray, T. and Hansen, P. and Novak, S. and Bennett, S. and Rodgers, M. and Baker-O{\textquoteright}Neal, B. and Sapp, B. and Barth, E. and Hedrick, J. and Goldblatt, R. and Rao, S. S. Papa and Osborn, K. D.} } @article {ISI:000475496800004, title = {Diabatic errors in Majorana braiding with bosonic bath}, journal = {Phys. Rev. B}, volume = {100}, number = {1}, year = {2019}, month = {JUL 12}, pages = {014511}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Majorana mode based topological qubits are potentially subject to diabatic errors that in principle can limit the utility of topological quantum computation. Using a combination of analytical and numerical methods we study the diabatic errors in Majorana-based topological Y junction that are coupled to a Bosonic bath in the Markovian approximation. We find that in the absence of a bath, the error can be made exponentially small with increasing braiding time, only when the time variation in the Hamiltonian is completely smooth. The presence of a dominantly dissipative Markovian bath is found to eliminate this exponential scaling of error to a power-law scaling as T-1 with T being the braiding time. However, the inclusion of relaxation improves this scaling slightly to go as T-2. Thus, coupling of topological systems to Bosonic baths can lead to power law in braiding time diabatic errors that might limit the speed of topologically protected operations using Majorana modes.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.014511}, author = {Nag, Amit and Sau, Jay D.} } @article {ISI:000455814100005, title = {Dynamic polarizability measurements with Lu-176(+)}, journal = {Phys. Rev. A}, volume = {99}, number = {1}, year = {2019}, month = {JAN 15}, pages = {012510}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We measure the differential polarizability of the Lu-176(+) S-1(0) <-> D-3(1) clock transition at multiple wavelengths. This experimentally characterizes the differential dynamic polarizability for frequencies up to 372 THz and allows an experimental determination of the dynamic correction to the blackbody radiation shift for the clock transition. In addition, measurements at the near resonant wavelengths of 598 and 646 nm determine the two dominant contributions to the differential dynamic polarizability below 372 THz. These additional measurements are carried out by two independent methods to verify the validity of our methodology. We also carry out a theoretical calculation of the polarizabilities using the hybrid method that combines the configuration interaction (CI) and the coupled-cluster approaches, incorporating for the first time quadratic nonlinear terms and partial triple excitations in the coupled-cluster calculations. The experimental measurements of the vertical bar < D-3(1)parallel to r parallel to P-3(J)>vertical bar matrix elements provide high-precision benchmarks for this theoretical approach.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.99.012510}, author = {Arnold, K. J. and Kaewuam, R. and Tan, T. R. and Porsev, S. G. and Safronova, M. S. and Barrett, M. D.} } @article {ISI:000482136700013, title = {Dynamic suppression of Rayleigh backscattering in dielectric resonators}, journal = {Optica}, volume = {6}, number = {8}, year = {2019}, month = {AUG 20}, pages = {1016-1022}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {The ultimate limits of performance for any classical optical system are set by sub-wavelength fluctuations within the host material, which may be frozen-in or even dynamically induced. The most common manifestation of such subwavelength disorder is Rayleigh light scattering, which is observed in nearly all waveguiding technologies today and can lead to both irreversible radiative losses as well as undesirable intermodal coupling, While it has been shown that backscattering from disorder can be suppressed by breaking the time-reversal symmetry in magneto-optic and topological insulator materials, common optical dielectrics possess neither of these properties. Here, we demonstrate an optomechanical approach for dynamically suppressing Rayleigh backscattering within dielectric resonators. We achieve this by locally breaking the time-reversal symmetry in a silica resonator through a Brillouin scattering interaction that is available in all materials. Near-complete suppression of Rayleigh backscattering is experimentally confirmed through two independent measurements-the elimination of a commonly seen normal-mode splitting or {\textquoteleft}{\textquoteleft}doublet{{\textquoteright}{\textquoteright}} effect and by measurement of the reduction in intrinsic optical loss. Additionally, a reduction of the back-reflections caused by disorder is also observed. Our results provide new evidence that it is possible to dynamically suppress Rayleigh backscattering within any optical dielectric medium using time-reversal symmetry breaking, for achieving robust light propagation in spite of scatterers or defects. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {2334-2536}, doi = {10.1364/OPTICA.6.001016}, author = {Kim, Seunghwi and Taylor, Jacob M. and Bahl, Gaurav} } @article {ISI:000466037000001, title = {Dynamical Hamiltonian engineering of 2D rectangular lattices in a one-dimensional ion chain}, journal = {npj Quantum Inform.}, volume = {5}, year = {2019}, month = {APR 26}, pages = {32}, publisher = {SPRINGERNATURE}, type = {Article}, abstract = {Controlling the interaction graph between spins or qubits in a quantum simulator allows user-controlled tailoring of native interactions to achieve a target Hamiltonian. Engineering long-ranged phonon-mediated spin-spin interactions in a trapped ion quantum simulator offers such a possibility. Trapped ions, a leading candidate for quantum simulation, are most readily trapped in a linear 1D chain, limiting their utility for readily simulating higher dimensional spin models. In this work, we introduce a hybrid method of analog-digital simulation for simulating 2D spin models which allows for the dynamic changing of interactions to achieve a new graph using a linear 1D chain. We focus this numerical work on engineering 2D rectangular nearest-neighbor spin lattices, demonstrating that the required control parameters scale linearly with ion number. This hybrid approach offers compelling possibilities for the use of 1D chains in the study of Hamiltonian quenches, dynamical phase transitions, and quantum transport in 2D and 3D.}, doi = {10.1038/s41534-019-0147-x}, author = {Rajabi, Fereshteh and Motlakunta, Sainath and Shih, Chung-You and Kotibhaskar, Nikhil and Quraishi, Qudsia and Ajoy, Ashok and Islam, Rajibul} } @article { ISI:000505563100013, title = {Dynamics of analog logic-gate networks for machine learning}, journal = {Chaos}, volume = {29}, number = {12}, year = {2019}, month = {DEC}, pages = {123130}, publisher = {AMER INST PHYSICS}, type = {Article}, abstract = {We describe the continuous-time dynamics of networks implemented on Field Programable Gate Arrays (FPGAs). The networks can perform Boolean operations when the FPGA is in the clocked (digital) mode; however, we run the programed FPGA in the unclocked (analog) mode. Our motivation is to use these FPGA networks as ultrafast machine-learning processors, using the technique of reservoir computing. We study both the undriven dynamics and the input response of these networks as we vary network design parameters, and we relate the dynamics to accuracy on two machine-learning tasks. Published under license by AIP Publishing.}, issn = {1054-1500}, doi = {10.1063/1.5123753}, author = {Shani, Itamar and Shaughnessy, Liam and Rzasa, John and Restelli, Alessandro and Hunt, Brian R. and Komkov, Heidi and Lathrop, Daniel P.} } @article {ISI:000483304200006, title = {Efficient telecom-to-visible spectral translation through ultralow power nonlinear nanophotonics}, journal = {Nat. Photonics}, volume = {13}, number = {9}, year = {2019}, month = {SEP}, pages = {593+}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {The ability to spectrally translate lightwave signals in a compact, low-power platform is at the heart of the promise of nonlinear nanophotonic technologies. For example, a device to connect the telecommunications band with visible and short near-infrared wavelengths can enable a connection between high-performance chip-integrated lasers based on scalable nanofabrication technology with atomic systems used for time and frequency metrology. Although second-order nonlinear (chi((2))) systems are the natural approach for bridging such large spectral gaps, here we show that third-order nonlinear (chi((3))) systems, despite their typically much weaker nonlinear response, can realize spectral translation with unprecedented performance. By combining resonant enhancement with nanophotonic mode engineering in a silicon nitride microring resonator, we demonstrate efficient spectral translation of a continuous-wave signal from the telecom band (similar to 1,550 nm) to the visible band (similar to 650 nm) through cavity-enhanced four-wave mixing. We achieve such translation over a wide spectral range >250 THz with a translation efficiency of (30.1 +/- 2.8)\% and using an ultralow pump power of (329 +/- 13) mu W. The translation efficiency projects to (274 +/- 28)\% at 1 mW and is more than an order of magnitude larger than what has been achieved in current nanophotonic devices.}, issn = {1749-4885}, doi = {10.1038/s41566-019-0464-9}, author = {Lu, Xiyuan and Moille, Gregory and Li, Qing and Westlyl, Daron A. and Singh, Anshuman and Rao, Ashutosh and Yu, Su-Peng and Briles, Travis C. and Papp, Scott B. and Srinivasan, Kartik} } @article {ISI:000466237600004, title = {Elastic rate coefficients for Li+H-2 collisions in the calibration of a cold-atom vacuum standard}, journal = {Phys. Rev. A}, volume = {99}, number = {4}, year = {2019}, month = {APR 29}, pages = {042704}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Ongoing efforts at the National Institute of Standards and Technology in creating a cold-atom vacuum standard device have prompted theoretical investigations of atom-molecule collision processes that characterize its operation. Such a device will operate as a primary standard for the ultrahigh-vacuum and extreme-high-vacuum regimes. This device operates by relating loss of ultracold lithium atoms from a conservative trap by collisions with ambient atoms and molecules to the background density and thus pressure through the ideal gas law. The predominant background constituent in these environments is molecular hydrogen H-2. We compute the relevant Li+H-2 Born-Oppenheimer potential energy surface, paying special attention to its uncertainty. Coupled-channel calculations are then used to obtain total rate coefficients, which include momentum-changing elastic and inelastic processes. We find that inelastic rotational quenching of H-2 is negligible near room temperature. For a (T = 300)-K gas of H-2 and 1.0-mu K gas of Li atoms prepared in a single hyperfine state, the total rate coefficients are 6.0(1) x 10(-9) cm(3)/s for both Li-6 and Li-7 isotopes, where the number in parentheses corresponds to a one-standard-deviation combined statistical and systematic uncertainty. We find that a 10-K increase in the H-2 temperature leads to a 1.9\% increase in the rate coefficients for both isotopes. For Li temperatures up to 100 mu K, changes are negligible. Finally, a semiclassical Born approximation significantly overestimates the rate coefficients. The difference is at least ten times the uncertainty of the coupled-channel result.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.99.042704}, author = {Makrides, Constantinos and Barker, Daniel S. and Fedchak, James A. and Scherschligt, Julia and Eckel, Stephen and Tiesinga, Eite} } @article {ISI:000460648100005, title = {Electric dipole matrix elements for the 6p(2)P(J) -> 7s(2)S(1/2) transition in atomic cesium}, journal = {Phys. Rev. A}, volume = {99}, number = {3}, year = {2019}, month = {MAR 5}, pages = {032504}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We report a measurement of the ratio of electric dipole transition matrix elements of cesium for the 6p(2)P(1/2) -> 7s(2)S(1/2) and 6p(2)P(3/2) -> 7s(2)S(1/2 )transitions. We determine this ratio of matrix elements through comparisons of two-color, two-photon excitation rates of the 7s(2)S(1/2) state using laser beams with polarizations parallel to one another vs perpendicular to one another. Our result of R < 7s(2)S(1/2)parallel to r parallel to 6P(2)P(3/2)>/< 7s(2)S(1/2)parallel to r parallel to 6P(2)P(1/2)> = 1.5272(17) is in excellent agreement with a theoretical prediction of R = 1.5270(27). Moreover, the accuracy of the experimental ratio is sufficiently high to differentiate between various theoretical approaches. To our knowledge, there are no prior experimental measurements of R. Combined with our recent determination of the lifetime of the 7s(2)S(1/2) state, we determine reduced matrix elements for these two transitions, < 7s(2)S(1/2)parallel to r parallel to 6P(2)P(3/2)> = -6.489(5)a(0) and < 7s(2)S(1/2)parallel to r parallel to 6P(2)P(1/2 >) = -4.249(4)a(0). These matrix elements are also in excellent agreement with theoretical calculations. These measurements improve knowledge of Cs properties needed for parity violation studies and provide benchmarks for tests of high-precision theory.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.99.032504}, author = {Toh, George and Damitz, Amy and Glotzbach, Nathan and Quirk, Jonah and Stevenson, I. C. and Choi, J. and Safronova, M. S. and Elliott, D. S.} } @article {ISI:000468201600010, title = {Electromagnetically induced transparency in inhomogeneously broadened solid media}, journal = {Phys. Rev. A}, volume = {99}, number = {5}, year = {2019}, month = {MAY 15}, pages = {053821}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study, theoretically and experimentally, electromagnetically induced transparency (EIT) in two different solid-state systems. Unlike many implementations in homogeneously broadened media, these systems exhibit inhomogeneous broadening of their optical and spin transitions typical of solid-state materials. We observe EIT line shapes typical of atomic gases, including a crossover into the regime of Autler-Townes splitting, but with the substitution of the inhomogeneous widths for the homogeneous values. We obtain quantitative agreement between experiment and theory for the width of the transparency feature over a range of optical powers and inhomogeneous linewidths. We discuss regimes over which analytical and numerical treatments capture the behavior. As solid-state systems become increasingly important for scalable and integratable quantum optical and photonic devices, it is vital to understand the effects of the inhomogeneous broadening that is ubiquitous in these systems. The treatment presented here can be applied to a variety of systems, as exemplified by the common scaling of experimental results from two different systems.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.99.053821}, author = {Fan, H. Q. and Kagalwala, K. H. and Polyakov, V, S. and Migdall, A. L. and Goldschmidt, E. A.} } @article {ISI:000466405300001, title = {Electronic structure of full-shell InAs/Al hybrid semiconductor-superconductor nanowires: Spin-orbit coupling and topological phase space}, journal = {Phys. Rev. B}, volume = {99}, number = {16}, year = {2019}, month = {APR 26}, pages = {161118}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study the electronic structure of full-shell superconductor-semiconductor nanowires, which have recently been proposed for creating Majorana zero modes, using an eight-band (k) over right arrow . (p) over right arrow model within a fully self-consistent Schrodinger-Poisson scheme. We find that the spin-orbit coupling induced by the intrinsic radial electric field is generically weak for subbands with their minimum near the Fermi energy. Furthermore, we show that the chemical potential windows consistent with the emergence of a topological phase are small and sparse and can only be reached by fine-tuning the diameter of the wire. These findings suggest that the parameter space consistent with the realization of a topological phase in full-shell InAs/Al nanowires is, at best, very narrow.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.161118}, author = {Woods, Benjamin D. and S. Das Sarma and Stanescu, Tudor D.} } @article {ISI:000468026100013, title = {Emergent gauge field and the Lifshitz transition of spin-orbit coupled bosons in one dimension}, journal = {Sci Rep}, volume = {9}, year = {2019}, month = {MAY 16}, pages = {7471}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {In the presence of strong spin-independent interactions and spin-orbit coupling, we show that the spinor Bose liquid confined to one spatial dimension undergoes an interaction-or density-tuned quantum phase transition similar to one theoretically proposed for itinerant magnetic solid-state systems. The order parameter describes broken Z2 inversion symmetry, with the ordered phase accompanied by non-vanishing momentum which is generated by fluctuations of an emergent dynamical gauge field at the phase transition. This quantum phase transition has dynamical critical exponent z similar or equal to 2, typical of a Lifshitz transition, but is described by a nontrivial interacting fixed point. From direct numerical simulation of the microscopic model, we extract previously unknown critical exponents for this fixed point. Our model describes a realistic situation of 1D ultracold atoms with Raman-induced spin-orbit coupling, establishing this system as a platform for studying exotic critical behavior of the Hertz-Millis type.}, issn = {2045-2322}, doi = {10.1038/s41598-019-43929-6}, author = {Cole, William S. and Lee, Junhyun and Mahmud, Khan W. and Alavirad, Yahya and Spielman, I. B. and Sau, Jay D.} } @article {ISI:000466716100027, title = {The end of artefacts}, journal = {Nat. Phys.}, volume = {15}, number = {5}, year = {2019}, month = {MAY}, pages = {518}, publisher = {NATURE PUBLISHING GROUP}, type = {Editorial Material}, issn = {1745-2473}, doi = {10.1038/s41567-019-0514-8}, author = {Phillips, William D.} } @article {ISI:000471983700002, title = {Equilibration of quasi-one-dimensional Fermi gases}, journal = {Phys. Rev. B}, volume = {99}, number = {24}, year = {2019}, month = {JUN 11}, pages = {245121}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {One-dimensional systems often possess multiple channels or bands arising from the excitation of transverse degrees of freedom. In this work, we study the specific processes that dominate the equilibration of multichannel Fermi gases at low temperatures. Focusing on the case of two channels, we perform an analysis of the relaxation properties of these systems by studying the spectrum and eigenmodes of the linearized collision integral. As an application of this analysis, a detailed calculation of the bulk viscosity is presented. The dominant scattering processes obey an unexpected conservation law which is likely to affect the hydrodynamic behavior of these systems.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.245121}, author = {DeGottardi, Wade and Matveev, K. A.} } @article {ISI:000476581500009, title = {Evanescent modes and step-like acoustic black holes}, journal = {Ann. Phys.}, volume = {407}, year = {2019}, month = {AUG}, pages = {148-165}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, type = {Article}, abstract = {We consider a model of an acoustic black hole formed by a quasi-one dimensional Bose-Einstein condensate with a step-like horizon. This system is analyzed by solving the corresponding Bogoliubov-de Gennes equation with an appropriate matching condition at the jump. When the step is between a subsonic and supersonic flow, a sonic horizon develops and in addition to the scattering coefficients we compute the distribution of the accompanying analogue Hawking radiation. Additionally, in response to the abrupt variation in flow and non-linear Bogoliubov dispersion relation, evanescent solutions of the Bogoliubov-de Gennes equation also appear and decay out from the horizon. We bound this decay length and show that these modes produce a modulation of observables outside the event horizon by their interference with outgoing Hawking flux. We go further and find specific superpositions of ingoing eigenmodes which exhibit coherent cancellation of the Hawking flux outside the horizon but nevertheless have evanescent support outside the black hole. We conclude by speculating that when quasiparticle interactions are included, evanescent modes may yield a leakage of information across the event horizon via interactions between the real outgoing Hawking flux and the virtual evanescent modes, and that we may expect this as a generic feature of models which break Lorentz invariance at the UV (Planck) scale. (C) 2019 Elsevier Inc. All rights reserved.}, keywords = {Acoustic black hole, Analogue gravity, Bogoliubov-de Gennes quasiparticle, Bose-Einstein condensate, Evanescent mode, Hawking radiation}, issn = {0003-4916}, doi = {10.1016/j.aop.2019.04.017}, author = {Curtis, Jonathan and Refael, Gil and Galitski, Victor} } @article {ISI:000473271300044, title = {Evolution of large-scale flow from turbulence in a two-dimensional superfluid}, journal = {Science}, volume = {364}, number = {6447}, year = {2019}, month = {JUN 28}, pages = {1267+}, publisher = {AMER ASSOC ADVANCEMENT SCIENCE}, type = {Article}, abstract = {Nonequilibrium interacting systems can evolve to exhibit large-scale structure and order. In two-dimensional turbulent flow, the seemingly random swirling motion of a fluid can evolve toward persistent large-scale vortices. To explain such behavior, Lars Onsager proposed a statistical hydrodynamic model based on quantized vortices. Here, we report on the experimental confirmation of Onsager{\textquoteright}s model. We dragged a grid barrier through an oblate superfluid Bose-Einstein condensate to generate nonequilibrium distributions of vortices. We observed signatures of an inverse energy cascade driven by the evaporative heating of vortices, leading to steady-state configurations characterized by negative absolute temperatures. Our results open a pathway for quantitative studies of emergent structures in interacting quantum systems driven far from equilibrium.}, issn = {0036-8075}, doi = {10.1126/science.aat5793}, author = {Johnstone, Shaun P. and Groszek, Andrew J. and Starkey, Philip T. and Billington, Christopher J. and Simula, Tapio P. and Helmerson, Kristian} } @article {ISI:000476695900010, title = {Exact Localized and Ballistic Eigenstates in Disordered Chaotic Spin Ladders and the Fermi-Hubbard Model}, journal = {Phys. Rev. Lett.}, volume = {123}, number = {3}, year = {2019}, month = {JUL 16}, pages = {036403}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We demonstrate the existence of exact atypical many-body eigenstates in a class of disordered, interacting one-dimensional quantum systems that includes the Fermi-Hubbard model as a special case. These atypical eigenstates, which generically have finite energy density and are exponentially many in number, are populated by noninteracting excitations. They can exhibit Anderson localization with area-law eigenstate entanglement or, surprisingly, ballistic transport at any disorder strength. These properties differ strikingly from those of typical eigenstates nearby in energy, which we show give rise to diffusive transport as expected in a chaotic quantum system. We discuss how to observe these atypical eigenstates in cold-atom experiments realizing the Fermi-Hubbard model, and comment on the robustness of their properties.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.036403}, author = {Iadecola, Thomas and Znidaric, Marko} } @article {ISI:000463834800010, title = {Excitations and correlations in the driven-dissipative Bose-Hubbard model}, journal = {Phys. Rev. A}, volume = {99}, number = {4}, year = {2019}, month = {APR 4}, pages = {043607}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Using a field-theoretic approach within the Schwinger-Keldysh formalism, we study a Bose-Hubbard model in the presence of a driving field and dissipation due to one-body losses. We recover the bistability diagram from the Gross-Pitaevski equation, and analyze the different phases with respect to their elementary excitations and correlations. We find the low-density solution to be subdivided into a dynamically instable, a gapped, and a gapless regime. The correlations decay exponentially, but a substantial increase of correlation length marks the regime of gapless excitations.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.99.043607}, author = {Grass, Tobias} } @article { ISI:000504435500005, title = {Ferromagnetism in quantum dot plaquettes}, journal = {Phys. Rev. B}, volume = {100}, number = {22}, year = {2019}, month = {DEC 23}, pages = {224421}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Following recent experimental progress concerning Nagaoka ferromagnetism in finite-size quantum dot plaquettes, a general theoretical analysis is warranted in order to ascertain in rather generic terms which arrangements of a small number of quantum dots can produce saturated ferromagnetic ground states and under which constraints on interaction and interdot tunneling in the plaquette. This is particularly necessary since Nagaoka ferromagnetism is fragile and arises only under rather special conditions. We test the robustness of ground state ferromagnetism in the presence of a long-range Coulomb interaction and long-range as well as short-range interdot hopping by modeling a wide range of different plaquette geometries accessible by arranging a few (similar to 4) quantum dots in a controlled manner. We find that ferromagnetism is robust to the presence of long-range Coulomb interactions, and we develop conditions constraining the tunneling strength such that the ground state is ferromagnetic. Additionally, we predict the presence of a partially spin-polarized ferromagnetic state for 4 electrons in a Y-shaped 4-quantum-dot plaquette. Finally, we consider 4 electrons in a ring of 5 dots. This does not satisfy the Nagaoka condition; however, we show that the ground state is spin 1 for strong, but not infinite, on-site interaction. Thus, even though Nagaoka{\textquoteright}s theorem does not apply, the ground state for the finite system with one hole in a ring of 5 dots is partially ferromagnetic. We provide detailed fully analytical results for the existence or not of ferromagnetic ground states in several quantum dot geometries which can be studied in currently available coupled quantum dot systems.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.224421}, author = {Buterakos, Donovan and Das Sarma, Sankar} } @article {ISI:000466889100001, title = {A fiber-integrated nanobeam single photon source emitting at telecom wavelengths}, journal = {Appl. Phys. Lett.}, volume = {114}, number = {17}, year = {2019}, month = {APR 29}, pages = {171101}, publisher = {AMER INST PHYSICS}, type = {Article}, abstract = {Fiber-coupled single photon sources are considered important components of photonics-based quantum information processors. Most fibercoupled single photon sources require careful alignment between fibers and quantum emitters. In this work, we present an alignment-free fiber-integrated single photon source based on an InAs/InP quantum dot emitting at telecom wavelengths. We designed a nanobeam containing the quantum dots attached to a fiber taper. The adiabatic tapered coupler of the nanobeam enables efficient light coupling to the fiber taper. Using a tungsten probe in a focused ion beam system, we transferred the nanobeam to the fiber taper. The observed fiber-coupled single photon emission occurs with a brightness of 1.4\% and a purity of 83\%. This device provides a building block for fiber-optic quantum circuits that have various applications, such as quantum communication and distributed quantum computing. Published under license by AIP Publishing.}, issn = {0003-6951}, doi = {10.1063/1.5089907}, author = {Lee, Chang-Min and Buyukkaya, Mustafa Atabey and Aghaeimeibodi, Shahriar and Karasahin, Aziz and Richardson, Christopher J. K. and Waks, Edo} } @conference {ISI:000482226300153, title = {First experimental steps toward an in situ gauge for direct measurement of relativistic intensities}, booktitle = {2019 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO)}, series = {Conference on Lasers and Electro-Optics}, year = {2019}, note = {Conference on Lasers and Electro-Optics (CLEO), San Jose, CA, MAY 05-10, 2019}, publisher = {IEEE; AdValue Photon; Amer Elements; Class5 Photon; Coherent; GoFoton; Light Convers; LightTrans; MKS; OZ Opt Online; Santec; ThorLabs; UQDevices; YSL Photon}, organization = {IEEE; AdValue Photon; Amer Elements; Class5 Photon; Coherent; GoFoton; Light Convers; LightTrans; MKS; OZ Opt Online; Santec; ThorLabs; UQDevices; YSL Photon}, type = {Proceedings Paper}, abstract = {Nearly 50 years ago Sarachik and Schappert suggested an intensity gauge based on wavelength shifts due to relativistic Thomson scattering. We present the first preliminary experimental results exploiting these shifts to make a direct measurement of peak intensities above 10(18) W/cm(2). (C) 2019 The Author(s)}, isbn = {978-1-943580-57-6}, issn = {2160-9020}, author = {Hill, III, W. T. and He, C. and Roso, L. and Perez-Hernandez, J. A. and Gatti, G. and de Marco, M. and Fedosejevs, R. and Longman, A.} } @article {ISI:000477908400014, title = {Fluctuation-dissipation and correlation-propagation relations from the nonequilibrium dynamics of detector-quantum field systems}, journal = {Phys. Rev. D}, volume = {100}, number = {2}, year = {2019}, month = {JUL 29}, pages = {025019}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We consider N uniformly accelerating Unruh-DeWitt detectors whose internal degrees of freedom are coupled to a massless scalar field in (1 + 1)D Minkowski space. We use the influence functional formalism to derive the Langevin equations governing the nonequilibrium dynamics of the internal degrees of freedom and show explicitly that the system relaxes in time and equilibrates. We also show that once the equilibrium condition is established a set of fluctuation-dissipation relations (FDRs) and correlation-propagation relations emerges for the detectors, extending earlier results of Raval, Hu, and Anglin {[}Stochastic theory of accelerated detectors in quantum fields, Phys. Rev. D 53, 7003 (1996)] which discovered these relations for the quantum field. Although similar in form to the FDRs commonly known from linear response theory, which assumes an equilibrium condition a priori, their physical connotations are dissimilar from that of a nonequilibrium origin. We show explicitly that both sets of relations are needed to guarantee the balance of energy flow in and out of the system in dynamical equilibrium with the field. These results are helpful to investigations of quantum information and communications of detectors in space experiments and inquiries of theoretical issues in black holes and cosmology.}, issn = {2470-0010}, doi = {10.1103/PhysRevD.100.025019}, author = {Hsiang, Jen-Tsung and Hu, B. L. and Lin, Shih-Yuin} } @article {ISI:000477924000099, title = {Fluctuation-dissipation and correlation-propagation relations in (1+3)D moving detector-quantum field systems}, journal = {Phys. Lett. B}, volume = {795}, year = {2019}, month = {AUG 10}, pages = {694-699}, publisher = {ELSEVIER}, type = {Article}, abstract = {The fluctuation-dissipation relations (FDR) are powerful relations which can capture the essence of the interplay between a system and its environment. Challenging problems of this nature which FDRs aid in our understanding include the backreaction of quantum field processes like particle creation on the spacetime dynamics in early universe cosmology or quantum black holes. The less familiar, yet equally important correlation-propagation relations (CPR) relate the correlations of stochastic forces on different detectors to the retarded and advanced parts of the radiation propagated in the field. Here, we analyze a system of N uniformly-accelerated Unruh-DeWitt detectors whose internal degrees of freedom (idf) are minimally coupled to a real, massless, scalar field in 4D Minkowski space, extending prior work in 2D with derivative coupling. Using the influence functional formalism, we derive the stochastic equations describing the nonequilibrium dynamics of the idfs. We show after the detector-field dynamics has reached equilibration the existence of the FDR and the CPR for the detectors, which combine to form a generalized fluctuation-dissipation matrix relation. We show explicitly the energy flows between the constituents of the system of detectors and between the system and the quantum field environment. This power balance anchors the generalized FDR. We anticipate this matrix relation to provide a useful guardrail in expounding some basic issues in relativistic quantum information, such as ensuring the self-consistency of the energy balance and tracking the quantum information transfer in the detector-field system. (C) 2019 The Authors. Published by Elsevier B.V.}, issn = {0370-2693}, doi = {10.1016/j.physletb.2019.06.062}, author = {Hsiang, Jen-Tsung and Hu, B. L. and Lin, Shih-Yuin and Yamamoto, Kazuhiro} } @article {14546, title = {Fluctuation-Induced Torque on a Topological Insulator out of Thermal Equilibrium}, journal = {Phys. Rev. Lett.}, volume = {123}, year = {2019}, month = {Aug}, pages = {055901}, doi = {10.1103/PhysRevLett.123.055901}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.123.055901}, author = {Maghrebi, M. F. and Gorshkov, A. V. and Sau, J. D.} } @article {ISI:000457058500007, title = {Fractional Josephson effect with and without Majorana zero modes}, journal = {Phys. Rev. B}, volume = {99}, number = {3}, year = {2019}, month = {JAN 29}, pages = {035312}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {It is known that the low-energy physics of the Josephson effect in the presence of Majorana zero modes exhibits a 4 pi periodicity as the Aharonov-Bohm flux varies in contrast to the 2 pi Josephson periodicity in usual superconducting junctions. We study this fractional Josephson effect in one-dimensional topological superconductors in Majorana nanowire systems by focusing on the features of the phase-energy relations in a superconducting semiconductor nanowire with spin-orbital coupling by including different factors operational in experimental systems, such as short wire length, suppression of superconducting gap, and the presence of an Andreev bound state. We show that even in the absence of the Majorana zero modes, some nontopological physical effects can manifest a 4 pi periodicity of the phase-energy relation in the Josephson junction, thus providing an alternative physics for fractional Josephson effect with no underlying Majorana zero modes. Furthermore, we consider several scenarios of inhomogeneous chemical potential distributions in the superconducting nanowire leading to four Majorana bound states and construct the effective four-Majorana model to correctly describe the low-energy theory of the Josephson effect. In this setup, multiple Majorana zero modes can also have the 4 pi fractional Josephson effect, although the underlying physics arises from Andreev bound states since two close-by Majorana bound states effectively form Andreev bound states. Our work demonstrates that the mere observation of a fractional Josephson effect simulating 4 pi periodicity might not, by itself, be taken as the definitive evidence for topological superconductivity. This finding has important implications for the ongoing search for non-Abelian Majorana zero modes and efforts for developing topological qubits.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.035312}, author = {Chiu, Ching-Kai and S. Das Sarma} } @article {ISI:000482940400006, title = {Frequency shifts due to Stark effects on a rubidium two-photon transition}, journal = {Phys. Rev. A}, volume = {100}, number = {2}, year = {2019}, month = {AUG 28}, pages = {023417}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The 5S(1/2) -> 5D(5/2) two-photon transition in Rb is of interest for the development of a compact optical atomic clock. Here we present a rigorous calculation of the 778.1-nm ac Stark shift {[}2.30(4) x 10(-13)(mW/mm(2))(-1)] that is in good agreement with our measured value of 2.5(2) x 10(-13)(mW/mm(2))(-1). We include a calculation of the temperature-dependent blackbody radiation (BBR) shift, and we predict that the clock could be operated either with zero net BBR shift {[}T = 495.9(27) K] or with zero first-order sensitivity {[}T = 368.1(14) K]. Also described is the calculation of the dc Stark shift of 5.5(1) x 10(-15)/(V/cm(2)) as well as clock sensitivities to optical alignment variations in both a cat{\textquoteright}s eye and a flat mirror retroreflector. Finally, we characterize these Stark effects, discussing mitigation techniques necessary to reduce final clock instabilities.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.100.023417}, author = {Martin, Kyle W. and Stuhl, Benjamin and Eugenio, Jon and Safronova, Marianna S. and Phelps, Gretchen and Burke, John H. and Lemke, Nathan D.} } @article {ISI:000452005100052, title = {Gateless and reversible Carrier density tunability in epitaxial graphene devices functionalized with chromium tricarbonyl}, journal = {Carbon}, volume = {142}, year = {2019}, month = {FEB}, pages = {468-474}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, abstract = {Monolayer epitaxial graphene (EG) has been shown to have clearly superior properties for the development of quantized Hall resistance (QHR) standards. One major difficulty with QHR devices based on EG is that their electrical properties drift slowly over time if the device is stored in air due to adsorption of atmospheric molecular dopants. The crucial parameter for device stability is the charge carrier density, which helps determine the magnetic flux density required for precise QHR measurements. This work presents one solution to this problem of instability in air by functionalizing the surface of EG devices with chromium tricarbonyl - Cr(CO)(3). Observations of carrier density stability in air over the course of one year are reported, as well as the ability to tune the carrier density by annealing the devices. For low temperature annealing, the presence of Cr(CO)(3) stabilizes the electrical properties and allows for the reversible tuning of the carrier density in millimeter-scale graphene devices close to the Dirac point. Precision measurements in the quantum Hall regime show no detrimental effect on the carrier mobility. Published by Elsevier Ltd.}, issn = {0008-6223}, doi = {10.1016/j.carbon.2018.10.085}, author = {Rigosi, Albert F. and Kruskopf, Mattias and Hill, Heather M. and Jin, Hanbyul and Wu, Bi-Yi and Johnson, Philip E. and Zhang, Siyuan and Berilla, Michael and Walker, Angela R. Hight and Hacker, Christina A. and Newell, David B. and Elmquist, Randolph E.} } @article { ISI:000493516700001, title = {Gauging fractons: Immobile non-Abelian quasiparticles, fractals, and position-dependent degeneracies}, journal = {Phys. Rev. B}, volume = {100}, number = {15}, year = {2019}, month = {OCT 29}, pages = {155146}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The study of gapped quantum many-body systems in three spatial dimensions has uncovered the existence of quantum states hosting quasiparticles that are confined, not by energetics but by the structure of local operators, to move along lower dimensional submanifolds. These so-called {\textquoteleft}{\textquoteleft}fracton{{\textquoteright}{\textquoteright}} phases are beyond the usual topological quantum field theory description, and thus require new theoretical frameworks to describe them. Here we consider coupling fracton models to topological quantum field theories in (3 + 1) dimensions by starting with two copies of a known fracton model and gauging the Z(2) symmetry that exchanges the two copies. This yields a class of exactly solvable lattice models that we study in detail for the case of the X-cube model and Haah{\textquoteright}s cubic code. The resulting phases host finite-energy non-Abelian immobile quasiparticles with robust degeneracies that depend on their relative positions. The phases also host non-Abelian string excitations with robust degeneracies that depend on the string geometry. Applying the construction to Haah{\textquoteright}s cubic code in particular provides an exactly solvable model with finite energy yet immobile non-Abelian quasiparticles that can only be created at the corners of operators with fractal support.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.155146}, author = {Bulmash, Daniel and Barkeshli, Maissam} } @article {14901, title = {Generation and detection of spin-orbit coupled neutron beams}, journal = {Proceedings of the National Academy of Sciences}, volume = {116}, year = {2019}, pages = {20328{\textendash}20332}, abstract = {Extensive interest has been placed on the techniques to prepare and characterize optical and matter wave orbital angular momentum (OAM) beams and spin correlated OAM beams. They have been shown to be useful in a wide range of applications such as microscopy, quantum information processing, material characterization, and communication protocols. Here we demonstrate an observation of spin-orbit beams and lattices of spin-orbit beams with neutrons. Neutrons, which do not possess a charge and have significant mass, are probes of nature that are complementary to photons and electrons. The techniques shown here enable neutron OAM applications in material characterization and fundamental physics.Spin-orbit coupling of light has come to the fore in nanooptics and plasmonics, and is a key ingredient of topological photonics and chiral quantum optics. We demonstrate a basic tool for incorporating analogous effects into neutron optics: the generation and detection of neutron beams with coupled spin and orbital angular momentum. The 3He neutron spin filters are used in conjunction with specifically oriented triangular coils to prepare neutron beams with lattices of spin-orbit correlations, as demonstrated by their spin-dependent intensity profiles. These correlations can be tailored to particular applications, such as neutron studies of topological materials.

}, issn = {0027-8424}, doi = {10.1073/pnas.1906861116}, url = {https://www.pnas.org/content/116/41/20328}, author = {Sarenac, Dusan and Kapahi, Connor and Chen, Wangchun and Clark, Charles W. and Cory, David G. and Huber, Michael G. and Taminiau, Ivar and Zhernenkov, Kirill and Pushin, Dmitry A.} } @article {ISI:000468210200030, title = {Graphene Devices for Tabletop and High-Current Quantized Hall Resistance Standards}, journal = {IEEE Trans. Instrum. Meas.}, volume = {68}, number = {6, SI}, year = {2019}, month = {JUN}, pages = {1870-1878}, publisher = {IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC}, type = {Article}, abstract = {We report the performance of a quantum Hall resistance standard based on epitaxial graphene maintained in a 5-T tabletop cryocooler system. This quantum resistance standard requires no liquid helium and can operate continuously, allowing year-round accessibility to quantized Hall resistance measurements. The nu = 2 plateau, with a value of R-K/2, also seen as RH, is used to scale to 1 k Omega using a binary cryogenic current comparator (BCCC) bridge and a direct current comparator (DCC) bridge. The uncertainties achieved with the BCCC are such as those obtained in the state-of-the-art measurements using GaAs-based devices. BCCC scaling methods can achieve large resistance ratios of 100 or more, and while room temperature DCC bridges have smaller ratios and lower current sensitivity, they can still provide alternate resistance scaling paths without the need for cryogens and superconducting electronics. Estimates of the relative uncertainties of the possible scaling methods are provided in this report, along with a discussion of the advantages of several scaling paths. The tabletop system limits are addressed as are potential solutions for using graphene standards at higher currents.}, keywords = {Binary cryogenic current comparator (BCCC), direct current comparator (DCC), Epitaxial graphene (EG), Metrology, quantized Hall resistance (QHR), standard resistor, standards and calibration}, issn = {0018-9456}, doi = {10.1109/TIM.2018.2882958}, author = {Rigosi, Albert F. and Panna, Alireza R. and Payagala, Shamith U. and Kruskopf, Mattias and Kraft, Marlin E. and Jones, George R. and Wu, Bi-Yi and Lee, Hsin-Yen and Yang, Yanfei and Hu, Jiuning and Jarrett, Dean G. and Newell, David B. and Elmquist, Randolph E.} } @article {ISI:000471944200018, title = {Griffiths physics in an ultracold Bose gas}, journal = {Phys. Rev. A}, volume = {99}, number = {6}, year = {2019}, month = {JUN 17}, pages = {063611}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Coupled XY model systems consisting of three-dimensional (3D) systems with disordered interlayer physics are of significant theoretical interest. We realize a set of coupled quasi-2D layers of Rb-87 in the presence of disordered interlayer coupling. This is achieved with our high bandwidth arbitrary optical lattice to obviate restrictions on the dimensionality of disorder with speckle-generated optical fields. We identify phase crossover regions compatible with the existence of a pair of intermediate Griffiths phases between a thermal state and the emergence of bulk 3D superfluidity.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.99.063611}, author = {Reed, M. E. W. and Smith, Z. S. and Dewan, Aftaab and Rolston, S. L.} } @article { ISI:000504638400005, title = {Ground state excitation of an atom strongly coupled to a free quantum field}, journal = {Phys. Rev. D}, volume = {100}, number = {12}, year = {2019}, month = {DEC 26}, pages = {125019}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {This paper presents a nonperturbative treatment of strong-coupling induced effects in atom-field systems which cannot be seen in traditional perturbative treatments invoking compromising assumptions such as the Born-Markov, rotating wave, or Fermi Golden rule. We consider an atom whose internal degrees of freedom are modeled by a harmonic oscillator which is bilinearly coupled to a scalar quantum field, representing one of the two polarizations of an electromagnetic field. Because the whole system is Gaussian we can solve this problem exactly. Using the open quantum system conceptual framework and the influence functional formalism we derive the dynamics of the reduced density matrix for the atom which enables the calculation of atomic transition probability and other relevant physical quantities. Finding an exact solution to this problem has the distinct advantage of enabling one to capture fully the strong coupling regime and discover interesting effects such as spontaneous ground state excitation {[}R. Passante, T. Petrosky, and I. Prigogine, Long-time behaviour of self-dressing and indirect spectroscopy, Physica (Amsterdam) 218A, 437 (1995).] which is unfathomable in perturbative treatments. The conventional description of atomic-optical activities is predicated on the assumption that the state of the total atom-field system is a product state of the atomic excitations and the photon number states, an assumption which is valid only for vanishingly weak coupling. The correct energy eigenfunctions to use should be that of the Hamiltonian of the combined atom-field system. Other features associated with finite to strong coupling effects such as resonance peak broadening and transition from a gapped to a gapless spectrum can all be understood from this perspective. Finally, to put the issues in a proper perspective we take the perturbative limit of the exact results and compare them with those from conventional time-dependent perturbation theory (TDPT). This enables one to pin-point where the deficiencies of TDPT lie as one removes the ultraweak coupling assumption.}, issn = {2470-0010}, doi = {10.1103/PhysRevD.100.125019}, author = {Hsiang, Jen-Tsung and Hu, Bei-Lok} } @article {ISI:000483803100006, title = {Ground state of the three-dimensional BCS d-wave superconductor}, journal = {Phys. Rev. B}, volume = {100}, number = {10}, year = {2019}, month = {SEP 4}, pages = {104503}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We determine the mean-field ground state of the three-dimensional rotationally symmetric d-wave (l = 2) superconductor at weak coupling. It is a noninert state, invariant under the symmetry C-2 only, which breaks time-reversal symmetry almost maximally, and features a high but again less-than-maximal average magnetization. The state obtained by minimization of the expanded sixth-order Ginzburg-Landau free energy is found to be an excellent approximation to the true ground state. The coupling to a parasitic s-wave component has only a minuscule quantitative and no qualitative effect on the ground state.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.104503}, author = {Herbut, Igor F. and Boettcher, Igor and Mandal, Subrata} } @article {ISI:000473018400004, title = {Ground-state degeneracy of non-Abelian topological phases from coupled wires}, journal = {Phys. Rev. B}, volume = {99}, number = {24}, year = {2019}, month = {JUN 20}, pages = {245138}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We construct a family of two-dimensional non-Abelian topological phases from coupled wires using a non-Abelian bosonization approach. We then demonstrate how to determine the nature of the non-Abelian topological order (in particular, the anyonic excitations and the topological degeneracy on the torus) realized in the resulting gapped phases of matter. This paper focuses on the detailed case study of a coupled-wire realization of the bosonic su(2)(2) Moore-Read state, but the approach we outline here can be extended to general bosonic su(2)(k) topological phases described by non-Abelian Chern-Simons theories. We also discuss possible generalizations of this approach to the construction of three-dimensional non-Abelian topological phases.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.245138}, author = {Iadecola, Thomas and Neupert, Titus and Chamon, Claudio and Mudry, Christopher} } @article { ISI:000489036000001, title = {Heisenberg-scaling measurement protocol for analytic functions with quantum sensor networks}, journal = {Phys. Rev. A}, volume = {100}, number = {4}, year = {2019}, month = {OCT 7}, pages = {042304}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We generalize past work on quantum sensor networks to show that, for d input parameters, entanglement can yield a factor O(d) improvement in mean-squared error when estimating an analytic function of these parameters. We show that the protocol is optimal for qubit sensors, and we conjecture an optimal protocol for photons passing through interferometers. Our protocol is also applicable to continuous variable measurements, such as one quadrature of a field operator. We outline a few potential applications, including calibration of laser operations in trapped ion quantum computing.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.100.042304}, author = {Qian, Kevin and Eldredge, Zachary and Ge, Wenchao and Pagano, Guido and Monroe, Christopher and Porto, V, J. and Gorshkov, V, Alexey} } @article {ISI:000467739200016, title = {Helical Hinge Majorana Modes in Iron-Based Superconductors}, journal = {Phys. Rev. Lett.}, volume = {122}, number = {18}, year = {2019}, month = {MAY 10}, pages = {187001}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Motivated by recent experiments on FeTe1-xSex, we construct an explicit minimal model of an iron-based superconductor with band inversion at the Z point and nontopological bulk s(+/-) pairing. While there has been considerable interest in Majorana zero modes localized at vortices in such systems, we find that our model-without any vortices-intrinsically supports 1D helical Majorana modes localized at the hinges between (001) and (100) or (010) surfaces, suggesting that this is a viable platform for observing {\textquoteleft}{\textquoteleft}higher-order{{\textquoteright}{\textquoteright}} topological superconductivity. We provide a general theory for these hinge modes and discuss their stability and experimental manifestation. Our work indicates the possible experimental observability of hinge Majorana modes in iron-based topological superconductors.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.122.187001}, author = {Zhang, Rui-Xing and Cole, William S. and S. Das Sarma} } @article {ISI:000465163400005, title = {Hierarchical Majoranas in a programmable nanowire network}, journal = {Phys. Rev. B}, volume = {99}, number = {15}, year = {2019}, month = {APR 19}, pages = {155138}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We propose a hierarchical architecture for building {\textquoteleft}{\textquoteleft}logical{{\textquoteright}{\textquoteright}} Majorana zero modes using {\textquoteleft}{\textquoteleft}physical{{\textquoteright}{\textquoteright}} Majorana zero modes at the Y-junctions of a hexagonal network of semiconductor nanowires. Each Y-junction contains three {\textquoteleft}{\textquoteleft}physical{{\textquoteright}{\textquoteright}} Majoranas, which hybridize when placed in close proximity, yielding a single effective Majorana mode near zero energy. The hybridization of effective Majorana modes on neighboring Y-junctions is controlled by applied gate voltages on the links of the honeycomb network. This gives rise to a tunable tight-binding model of effective Majorana modes. We show that selecting the gate voltages that generate a Kekule vortex pattern in the set of hybridization amplitudes yields an emergent {\textquoteleft}{\textquoteleft}logical{{\textquoteright}{\textquoteright}} Majorana zero mode bound to the vortex core. The position of a logical Majorana can be tuned adiabatically, without moving any of the {\textquoteleft}{\textquoteleft}physical{{\textquoteright}{\textquoteright}} Majoranas or closing any energy gaps, by programming the values of the gate voltages to change as functions of time. A nanowire network supporting multiple such {\textquoteleft}{\textquoteleft}logical{{\textquoteright}{\textquoteright}} Majorana zero modes provides a physical platform for performing adiabatic non-Abelian braiding operations in a fully controllable manner.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.155138}, author = {Yang, Zhi-Cheng and Iadecola, Thomas and Chamon, Claudio and Mudry, Christopher} } @article { ISI:000488282800085, title = {High purity single photons entangled with an atomic qubit}, journal = {Opt. Express}, volume = {27}, number = {20}, year = {2019}, month = {SEP 30}, pages = {28143-28149}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {Trapped atomic ions are an ideal candidate for quantum network nodes, with long-lived identical qubit memories that can be locally entangled through their Coulomb interaction and remotely entangled through photonic channels. The integrity of this photonic interface is generally reliant on the purity of single photons produced by the quantum memory. Here, we demonstrate a single-photon source for quantum networking based on a trapped Ba-138(+) ion with a single photon purity of g((2))(0) = (8.1 +/- 2.3) x 10(-5) without background subtraction. We further optimize the tradeoff between the photonic generation rate and the memory-photon entanglement fidelity for the case of polarization photonic qubits by tailoring the spatial mode of the collected light. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {1094-4087}, doi = {10.1364/OE.27.028143}, author = {Crocker, C. and Lichtman, M. and Sosnova, K. and Carter, A. and Scarano, S. and Monroe, C.} } @article { ISI:000498883600001, title = {High-Coherence Fluxonium Qubit}, journal = {Phys. Rev. X}, volume = {9}, number = {4}, year = {2019}, month = {NOV 25}, pages = {041041}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We report superconducting fluxonium qubits with coherence times largely limited by energy relaxation and reproducibly satisfying T-2 > 100 mu s (T-2 > 400 mu s in one device). Moreover, given the state-of-the-art values of the surface loss tangent and the 1/f flux-noise amplitude, the coherence time can be further improved beyond 1 ms. Our results violate a common viewpoint that the number of Josephson junctions in a superconducting circuit-over 10(2) here-must be minimized for best qubit coherence. We outline how the unique to fluxonium combination of long coherence time and large anharmonicity can benefit both gate-based and adiabatic quantum computing.}, issn = {2160-3308}, doi = {10.1103/PhysRevX.9.041041}, author = {Nguyen, Long B. and Lin, Yen-Hsiang and Somoroff, Aaron and Mencia, Raymond and Grabon, Nicholas and Manucharyan, Vladimir E.} } @article {15801, title = {Higher-Order Topology and Nodal Topological Superconductivity in Fe(Se,Te) Heterostructures}, journal = {Phys. Rev. Lett.}, volume = {123}, year = {2019}, month = {Oct}, pages = {167001}, doi = {10.1103/PhysRevLett.123.167001}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.123.167001}, author = {Zhang, Rui-Xing and Cole, William S. and Wu, Xianxin and S Das Sarma} } @article { ISI:000496923500007, title = {High-precision measurement and ab initio calculation of the (6s(2)6p(2)) P-3(0) -> P-3(2) electric-quadrupole-transition amplitude in Pb-208}, journal = {Phys. Rev. A}, volume = {100}, number = {5}, year = {2019}, month = {NOV 18}, pages = {052506}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We have completed a measurement of the (6s(2)6p(2)) P-3(0) -> P-3(2) 939 nm electric quadrupole (E2) transition amplitude in atomic lead. Using a Faraday rotation spectroscopy technique and a sensitive polarimeter, we have measured this very weak E2 transition, and determined its amplitude to be < P-3(2) parallel to Q parallel to P-3(0)> = 8.91(9) a.u. We also present an ab initio theoretical calculation of this matrix element, determining its value to be 8.86(5) a.u., which is in excellent agreement with the experimental result. We heat a quartz vapor cell containing Pb-208 to between 800 and 940 degrees C, apply a similar to 10 G longitudinal magnetic field, and use polarization modulation and lock-in detection to measure optical rotation amplitudes of order 1 mrad with noise near 1 mu rad. We compare the Faraday rotation amplitude of the E2 transition to that of the P-3(0)-P-3(1) 1279 nm magnetic dipole (M1) transition under identical sample conditions.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.100.052506}, author = {Maser, Daniel L. and Hoenig, Eli and Wang, B-Y and Rupasinghe, P. M. and Porsev, S. G. and Safronova, M. S. and Majumder, P. K.} } @article {ISI:000465439100022, title = {Hot electron heatsinks for microwave attenuators below 100 mK}, journal = {Appl. Phys. Lett.}, volume = {114}, number = {15}, year = {2019}, month = {APR 15}, pages = {152602}, publisher = {AMER INST PHYSICS}, type = {Article}, abstract = {We demonstrate improvements to the cooling power of broad bandwidth (10 GHz) microwave attenuators designed for operation at temperatures below 100 mK. By interleaving 9-mu m thick conducting copper heatsinks in between 10-mu m long, 70-nm thick resistive nichrome elements, the electrical heat generated in the nichrome elements is conducted more readily into the heatsinks, effectively decreasing the thermal resistance between the hot electrons and cold phonons. For a 20 dB attenuator mounted at 20 mK, a minimum noise temperature of T-n similar to 50 mK was obtained for small dissipated powers (P-d < 1 nW) in the attenuator. For higher dissipated powers, we find T-n proportional to P-d(1/4.4), with P-d = 100 nW corresponding to a noise temperature of 90 mK. This is in good agreement with thermal modeling of the system and represents nearly a factor of 20 improvement in cooling power or a factor of 1.8 reduction in T-n for the same dissipated power, when compared to a previous design without interleaved heatsinks. Published under license by AIP Publishing.}, issn = {0003-6951}, doi = {10.1063/1.5097369}, author = {Yeh, Jen-Hao and Huang, Yizhou and Zhang, Rui and Premaratne, Shavindra and LeFebvre, Jay and Wellstood, F. C. and Palmer, B. S.} } @article {ISI:000473755200026, title = {Hyperbolic lattices in circuit quantum electrodynamics}, journal = {Nature}, volume = {571}, number = {7763}, year = {2019}, month = {JUL 4}, pages = {45+}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {After two decades of development, cavity quantum electrodynamics with superconducting circuits has emerged as a rich platform for quantum computation and simulation. Lattices of coplanar waveguide resonators constitute artificial materials for microwave photons, in which interactions between photons can be incorporateded either through the use of nonlinear resonator materials or through coupling between qubits and resonators. Here we make use of the previously overlooked property that these lattice sites are deformable and permit tight-binding lattices that are unattainable even in solid-state systems. We show that networks of coplanar waveguide resonators can create a class of materials that constitute lattices in an effective hyperbolic space with constant negative curvature. We present numerical simulations of hyperbolic analogues of the kagome lattice that show unusual densities of states in which a macroscopic number of degenerate eigenstates comprise a spectrally isolated flat band. We present a proof-of-principle experimental realization of one such lattice. This paper represents a step towards on-chip quantum simulation of materials science and interacting particles in curved space.}, issn = {0028-0836}, doi = {10.1038/s41586-019-1348-3}, author = {Kollar, Alicia J. and Fitzpatrick, Mattias and Houck, Andrew A.} } @article { ISI:000493335100001, title = {Identification of advanced spin-driven thermoelectric materials via interpretable machine learning}, journal = {npj Comput. Mater.}, volume = {5}, year = {2019}, month = {OCT 30}, pages = {103}, publisher = {SPRINGERNATURE}, type = {Article}, abstract = {Machine learning is becoming a valuable tool for scientific discovery. Particularly attractive is the application of machine learning methods to the field of materials development, which enables innovations by discovering new and better functional materials. To apply machine learning to actual materials development, close collaboration between scientists and machine learning tools is necessary. However, such collaboration has been so far impeded by the black box nature of many machine learning algorithms. It is often difficult for scientists to interpret the data-driven models from the viewpoint of material science and physics. Here, we demonstrate the development of spin-driven thermoelectric materials with anomalous Nernst effect by using an interpretable machine learning method called factorized asymptotic Bayesian inference hierarchical mixture of experts (FAB/HMEs). Based on prior knowledge of material science and physics, we were able to extract from the interpretable machine learning some surprising correlations and new knowledge about spin-driven thermoelectric materials. Guided by this, we carried out an actual material synthesis that led to the identification of a novel spin-driven thermoelectric material. This material shows the largest thermopower to date.}, issn = {2057-3960}, doi = {10.1038/s41524-019-0241-9}, author = {Iwasaki, Yuma and Sawada, Ryohto and Stanev, Valentin and Ishida, Masahiko and Kirihara, Akihiro and Omori, Yasutomo and Someya, Hiroko and Takeuchi, Ichiro and Saitoh, Eiji and Yorozu, Shinichi} } @article {ISI:000473013000002, title = {Identification of superconducting pairing symmetry in twisted bilayer graphene using in-plane magnetic field and strain}, journal = {Phys. Rev. B}, volume = {99}, number = {22}, year = {2019}, month = {JUN 25}, pages = {220507}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We show how the pairing symmetry of superconducting states in twisted bilayer graphene can be experimentally identified by theoretically studying effects of externally applied in-plane magnetic field and strain. In the low-field regime, superconducting critical temperature T-c is suppressed by in-plane magnetic field B-parallel to in singlet channels, but is enhanced by weak B-parallel to in triplet channels, providing an important distinction. The in-plane angular dependence of the critical B-parallel to,B-c has a sixfold rotational symmetry, which is broken when strain is present. We show that anisotropy in B-parallel to,B-c generated by strain can be similar for s- and d-wave channels in moire superlattices. The d-wave state is pinned to be nematic by strain and consequently gapless, which is distinguishable from the fully gapped s-wave state by tunneling gap measurements.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.220507}, author = {Wu, Fengcheng and S. Das Sarma} } @article {ISI:000467473500012, title = {Imaging topology of Hofstadter ribbons}, journal = {New J. Phys.}, volume = {21}, year = {2019}, month = {MAY 8}, pages = {053021}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {Physical systems with non-trivial topological order find direct applications in metrology (Klitzing et al 1980 Phys. Rev. Lett. 45 494-7) and promise future applications in quantum computing (Freedman 2001 Found. Comput. Math. 1 183-204; Kitaev 2003 Ann. Phys. 303 2-30). The quantum Hall effect derives from transverse conductance, quantized to unprecedented precision in accordance with the system{\textquoteright}s topology (Laughlin 1981 Phys. Rev. B 23 5632-33). At magnetic fields beyond the reach of current condensed matter experiment, around 10(4)T, this conductance remains precisely quantized with values based on the topological order (Thouless et al 1982 Phys. Rev. Lett. 49 405-8). Hitherto, quantized conductance has only been measured in extended 2D systems. Here, we experimentally studied narrow 2D ribbons, just 3 or 5 sites wide along one direction, using ultracold neutral atoms where such large magnetic fields can be engineered (Jaksch and Zoller 2003 New J. Phys. 5 56; Miyake et al 2013 Phys. Rev. Lett. 111 185302; Aidelsburger et al 2013 Phys. Rev. Lett. 111 185301; Celi et al 2014 Phys. Rev. Lett. 112 043001; Stuhl et al 2015 Science 349 1514; Mancini et al 2015 Science 349 1510; An et al 2017 Sci. Adv. 3). We microscopically imaged the transverse spatial motion underlying the quantized Hall effect. Our measurements identify the topological Chern numbers with typical uncertainty of 5\%, and show that although band topology is only properly defined in infinite systems, its signatures are striking even in nearly vanishingly thin systems.}, keywords = {quantum Hall effect, quantum simulation, quantum transport, ultracold atoms}, issn = {1367-2630}, doi = {10.1088/1367-2630/ab165b}, author = {Genkina, Dina and Aycock, Lauren M. and Lu, I, Hsin- and Lu, Mingwu and Pineiro, Alina M. and Spielman, I. B.} } @article {ISI:000455683000004, title = {Implementation of a generalized controlled-NOT gate between fixed-frequency transmons}, journal = {Phys. Rev. A}, volume = {99}, number = {1}, year = {2019}, month = {JAN 11}, pages = {012317}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We have embedded two fixed-frequency Al/AlOx/Al transmons, with ground-to-excited transition frequencies at 6.0714 and 6.7543 GHz, in a single three-dimensional Al cavity with a fundamental mode at 7.7463 GHz. Strong coupling between the cavity and each transmon results in an effective qubit-qubit coupling strength of 26 MHz and a -1 MHz dispersive shift in each qubit{\textquoteright}s transition frequency, depending on the state of the other qubit. Using the all-microwave SWIPHT (speeding up wave forms by inducing phases to harmful transitions) technique {[}Economou and Barnes, Phys. Rev. B 91, 161405 (2015)], we demonstrate the operation of a generalized controlled-NOT gate between the two qubits, with a gate time of tau(g) = 907 ns optimized for this device. Using quantum process tomography we find that the gate fidelity is 83-84\%, somewhat less than the 87\% fidelity expected from relaxation and dephasing in the transmons during the gate time.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.99.012317}, author = {Premaratne, Shavindra P. and Yeh, Jen-Hao and Wellstood, F. C. and Palmer, B. S.} } @article {ISI:000459579600002, title = {Incorporation of random alloy GaBixAs1-x barriers in InAs quantum dot molecules: Energy levels and confined hole states}, journal = {Phys. Rev. B}, volume = {99}, number = {7}, year = {2019}, month = {FEB 22}, pages = {075308}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Self-assembled InAs quantum dots (QDs), which have long hole-spin coherence times and are amenable to optical control schemes, have long been explored as building blocks for qubit architectures. One such design consists of vertically stacking two QDs to create a QD molecule (QDM) and using the spin-mixing properties of {\textquoteleft}{\textquoteleft}moleculelike{{\textquoteright}{\textquoteright}} coupled hole states for all-optical qubit manipulation. In this paper, the first of two papers, we introduce the incorporation of dilute GaBixAs1-x alloys in the barrier region between the two dots. GaBixAs1-x is expected to increase the spin mixing of the molecular states needed for qubit operations by raising the barrier valence-band edge and spin-orbit splitting. Using an atomistic tight-binding model, we compute the properties of GaBixAs1-x and the modification of hole states that arise when the alloy is used in the barrier of an InAs QDM. An atomistic treatment is necessary to correctly capture nontraditional alloy effects such as the band-anticrossing valence band. It also allows for the study of configurational variances and clustering effects of the alloy. We find that in InAs QDMs with a GaBiAs interdot barrier, electron states are not strongly affected by the inclusion of Bi. However, hole states are much more sensitive to the presence and configuration of Bi in the barriers. By independently studying the alloy-induced strain and electronic scattering off Bi and As orbitals, we conclude that an initial increase in QDM hole-state energy at low Bi concentration is caused by the alloy-induced strain. We further find that the decrease in QDM hole energy at higher Bi concentrations can only be explained when both alloy strain and orbital effects are considered. In our second paper, we use the understanding developed here to discuss how the alloyed barriers contribute to enhancement in hole spin-mixing and the implications for QDM qubit architectures.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.075308}, author = {Lin, Arthur and Doty, Matthew F. and Bryant, Garnett W.} } @article { ISI:000490353500059, title = {Indistinguishable Photons from Deterministically Integrated Single Quantum Dots in Heterogeneous GaAs/Si3N4 Quantum Photonic Circuits}, journal = {Nano Lett.}, volume = {19}, number = {10}, year = {2019}, month = {OCT}, pages = {7164-7172}, publisher = {AMER CHEMICAL SOC}, type = {Article}, abstract = {Silicon photonics enables scaling of quantum photonic systems by allowing the creation of extensive, low-loss, reconfigurable networks linking various functional on-chip elements. Inclusion of single quantum emitters onto photonic circuits, acting as on-demand sources of indistinguishable photons or single-photon nonlinearities, may enable large-scale chip-based quantum photonic circuits and networks. Toward this, we use low-temperature in situ electron-beam lithography to deterministically produce hybrid GaAs/Si3N4 photonic devices containing single InAs quantum dots precisely located inside nanophotonic structures, which act as efficient, Si3N4 waveguide-coupled on-chip, on-demand single-photon sources. The precise positioning afforded by our scalable fabrication method furthermore allows observation of postselected indistinguishable photons. This indicates a promising path toward significant scaling of chip-based quantum photonics, enabled by large fluxes of indistinguishable single-photons produced on-demand, directly on-chip.}, keywords = {deterministic sample fabrication, hybrid devices, indistinguishable photons, Quantum Dots, Quantum optics}, issn = {1530-6984}, doi = {10.1021/acs.nanolett.9b02758}, author = {Schnauber, Peter and Singh, Anshuman and Schall, Johannes and Park, Suk In and Song, Jin Dong and Rodt, Sven and Srinivasan, Kartik and Reitzenstein, Stephan and Davanco, Marcelo} } @conference {ISI:000482226301193, title = {Integration of Quantum Emitters with Lithium Niobate Photonics}, booktitle = {2019 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO)}, series = {Conference on Lasers and Electro-Optics}, year = {2019}, note = {Conference on Lasers and Electro-Optics (CLEO), San Jose, CA, MAY 05-10, 2019}, publisher = {IEEE; AdValue Photon; Amer Elements; Class5 Photon; Coherent; GoFoton; Light Convers; LightTrans; MKS; OZ Opt Online; Santec; ThorLabs; UQDevices; YSL Photon}, organization = {IEEE; AdValue Photon; Amer Elements; Class5 Photon; Coherent; GoFoton; Light Convers; LightTrans; MKS; OZ Opt Online; Santec; ThorLabs; UQDevices; YSL Photon}, type = {Proceedings Paper}, abstract = {We demonstrate integration of telecom quantum dots with lithium niobate photonics using a pick-and-place technique. Second order photon correlation measurement performed with an on-chip beamsplitter confirms the single-photon nature of the emission. (C) 2019 The Author(s)}, isbn = {978-1-943580-57-6}, issn = {2160-9020}, author = {Aghaeimeibodi, Shahriar and Desiatov, Boris and Kim, Je-Hyung and Lee, Chang-Min and Buyukkaya, Mustafa Atabey and Karasahin, Aziz and Richardson, Christopher J. K. and Leavitt, Richard P. and Loncar, Marko and Waks, Edo} } @article { ISI:000457704900001, title = {Interacting Qubit-Photon Bound States with Superconducting Circuits}, journal = {PHYSICAL REVIEW X}, volume = {9}, number = {1}, year = {2019}, month = {FEB 1}, pages = {011021}, issn = {2160-3308}, doi = {10.1103/PhysRevX.9.011021}, author = {Sundaresan, Neereja M. and Lundgren, Rex and Zhu, Guanyu and Gorshkov, V, Alexey and Houck, Andrew A.} } @article {ISI:000469902700001, title = {Interaction-induced transition in the quantum chaotic dynamics of a disordered metal}, journal = {Ann. Phys.}, volume = {405}, year = {2019}, month = {JUN}, pages = {1-13}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, type = {Article}, abstract = {We demonstrate that a weakly disordered metal with short-range interactions exhibits a transition in the quantum chaotic dynamics when changing the temperature or the interaction strength. For weak interactions, the system displays exponential growth of the out-of-time-ordered correlator (OTOC) of the current operator. The Lyapunov exponent of this growth is temperature-independent in the limit of vanishing interaction. With increasing the temperature or the interaction strength, the system undergoes a transition to a non-chaotic behaviour, for which the exponential growth of the OTOC is absent. We conjecture that the transition manifests itself in the quasiparticle energy-level statistics and also discuss ways of its explicit observation in cold-atom setups. (C) 2019 Elsevier Inc. All rights reserved.}, issn = {0003-4916}, doi = {10.1016/j.aop.2019.03.008}, author = {Syzranov, V, S. and Gorshkov, V, A. and Galitski, V. M.} } @article {14826, title = {Interference of Temporally Distinguishable Photons Using Frequency-Resolved Detection}, journal = {Phys. Rev. Lett.}, volume = {123}, year = {2019}, month = {Sep}, pages = {123603}, doi = {10.1103/PhysRevLett.123.123603}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.123.123603}, author = {Orre, Venkata Vikram and Goldschmidt, Elizabeth A. and Deshpande, Abhinav and Gorshkov, Alexey V. and Tamma, Vincenzo and Hafezi, Mohammad and Mittal, Sunil} } @article {ISI:000467378000002, title = {Interplay between magnetic and vestigial nematic orders in the layered J(1)-J(2) classical Heisenberg model}, journal = {Phys. Rev. B}, volume = {99}, number = {17}, year = {2019}, month = {MAY 6}, pages = {174404}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study the layered J(1)-J(2) classical Heisenberg model on the square lattice using a self-consistent bond theory. We derive the phase diagram for fixed J(1) as a function of temperature T, J(2), and interplane coupling J(z). Broad regions of (anti)ferromagnetic and stripe order are found, and are separated by a first-order transition near J(2) approximate to 0.5 (in units of vertical bar J(1)vertical bar). Within the stripe phase the magnetic and vestigial nematic transitions occur simultaneously in first-order fashion for strong J(z). For weaker J(z), there is in addition, for J(2){*} < J(2) < J(2){*}{*}, an intermediate regime of split transitions implying a finite temperature region with nematic order but no long-range stripe magnetic order. In this split regime, the order of the transitions depends sensitively on the deviation from J(2){*} and J(2){*}{*}, with split second-order transitions predominating for J(2){*} << J(2) << J(2){*}{*}. We find that the value of J(2){*} depends weakly on the interplane coupling and is just slightly larger than 0.5 for vertical bar J(z)vertical bar less than or similar to 0.01. In contrast, the value of J(2){*}{*} increases quickly from J(2){*} at vertical bar J(z)vertical bar less than or similar to 0.01 as the interplane coupling is further reduced. In addition, the magnetic correlation length is shown to directly depend on the nematic order parameter and thus exhibits a sharp increase (or jump) upon entering the nematic phase. Our results are broadly consistent with the predictions based on itinerant electron models of the iron-based superconductors in the normal state and, thus, help substantiate a classical spin framework for providing a phenomenological description of their magnetic properties.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.174404}, author = {Syljuasen, Olav F. and Paaske, Jens and Schecter, Michael} } @article { ISI:000459554300005, title = {Large stark tuning of InAs/InP quantum dots}, journal = {APPLIED PHYSICS LETTERS}, volume = {114}, number = {7}, year = {2019}, month = {FEB 18}, pages = {071105}, issn = {0003-6951}, doi = {10.1063/1.5082560}, author = {Aghaeimeibodi, Shahriar and Lee, Chang-Min and Buyukkaya, Mustafa Atabey and Richardson, Christopher J. K. and Waks, Edo} } @article {ISI:000457732400003, title = {Linear-in-T resistivity in dilute metals: A Fermi liquid perspective}, journal = {Phys. Rev. B}, volume = {99}, number = {8}, year = {2019}, month = {FEB 4}, pages = {085105}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We consider a short-range deformation-potential scattering model of electron-acoustic phonon interaction to calculate the resistivity of an ideal metal (i.e., no other scattering mechanism except acoustic phonon scattering) as a function of temperature (T) and electron density (n). The resistivity calculation is based on the Boltzmann transport theory within the relaxation-time approximation in the nearly-free-electron single-band approximation. We consider both 3D metals and 2D metals and focus on the dilute limit, i.e., low effective metallic carrier density (and hence low effective Fermi wave number k(F)) of the system. The main findings are (1) a phonon-scattering-induced linear-in-T resistivity could persist to arbitrarily low temperatures in the dilute limit independent of the Debye temperature (T-D), although, eventually, the low-T resistivity turns over to the expected Bloch-Grfineisen (BG) behavior with T-5(T-4) dependence, in 3D (2D), respectively, with the crossover temperature, T-BG, from the linear-in-T to the BG behavior, being proportional to the Fermi momentum, is small in the dilute limit; (2) because of low values of n, the phonon-induced resistivity could be very high in the system, orders of magnitude above the corresponding room temperature resistivity of ordinary metals; and (3) the resistivity shows an intrinsic saturation effect at very high temperatures (for T > T-D) and, in fact, weakly decreases with increasing T above a high crossover temperature with this crossover being dependent on both T-D and n in a nonuniversal manner-this high-temperature crossover is not directly connected with the Mott-Ioffe-Regel limit and is a reflection of phonon phase-space restriction. We discuss the qualitative trends in the resistivity as a function of temperature, density, phonon velocity, and system dimensionality. We also provide {\textquoteleft}{\textquoteleft}high-temperature{{\textquoteright}{\textquoteright}} linear-in-T resistivity results for 2D and 3D Dirac materials. Our work brings out the universal features of phonon-induced transport in dilute metals, and we comment on possible implications of our results for strange metals, emphasizing that the mere observation of a linear-in-T metallic resistivity at low temperatures or a very high metallic resistivity at high temperatures is not necessarily a reason to invoke an underlying quantum critical strange-metal behavior. Dilute metals may very well have highly unusual (compared with normal metals) transport properties arising from quantitative, but not qualitatively new, underlying physics. We discuss the temperature variation of the effective transport scattering rate showing that, for reasonable parameters, the scattering rate could be below or above k(B)T and, in particular, purely coincidentally, the calculated scattering rate happens to be k(B)T in normal metals with no implications whatsoever for the so-called Planckian behavior. Our work manifestly establishes that an apparent Planckian dissipative behavior could arise from the usual electron-phonon interaction without implying any strange metallicity or a failure of the quasiparticle paradigm in contrast to recent claims.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.085105}, author = {Hwang, E. H. and S. Das Sarma} } @article {ISI:000474892400001, title = {Locality and Digital Quantum Simulation of Power-Law Interactions}, journal = {Phys. Rev. X}, volume = {9}, number = {3}, year = {2019}, month = {JUL 10}, pages = {031006}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The propagation of information in nonrelativistic quantum systems obeys a speed limit known as a Lieb-Robinson bound. We derive a new Lieb-Robinson bound for systems with interactions that decay with distance r as a power law, 1/r(alpha). The bound implies an effective light cone tighter than all previous bounds. Our approach is based on a technique for approximating the time evolution of a system, which was first introduced as part of a quantum simulation algorithm by Haah et al., FOCS{\textquoteright} 18. To bound the error of the approximation, we use a known Lieb-Robinson bound that is weaker than the bound we establish. This result brings the analysis full circle, suggesting a deep connection between Lieb-Robinson bounds and digital quantum simulation. In addition to the new Lieb-Robinson bound, our analysis also gives an error bound for the Haah et al. quantum simulation algorithm when used to simulate power-law decaying interactions. In particular, we show that the gate count of the algorithm scales with the system size better than existing algorithms when alpha > 3D (where D is the number of dimensions).}, issn = {2160-3308}, doi = {10.1103/PhysRevX.9.031006}, author = {Tran, Minh C. and Guo, Andrew Y. and Su, Yuan and Garrison, James R. and Eldredge, Zachary and Foss-Feig, Michael and Childs, Andrew M. and Gorshkov, Alexey V.} } @article { ISI:000456992300001, title = {Machine learning techniques for state recognition and auto-tuning in quantum dots}, journal = {NPJ QUANTUM INFORMATION}, volume = {5}, year = {2019}, month = {JAN 21}, pages = {6}, issn = {2056-6387}, doi = {10.1038/s41534-018-0118-7}, author = {Kalantre, Sandesh S. and Zwolak, Justyna P. and Ragole, Stephen and Wu, Xingyao and Zimmerman, Neil M. and Stewart, Jr., M. D. and Taylor, Jacob M.} } @article { ISI:000503808100004, title = {Manifestations of spin-orbit coupling in a cuprate superconductor}, journal = {Phys. Rev. B}, volume = {100}, number = {22}, year = {2019}, month = {DEC 20}, pages = {224512}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Exciting new work on Bi2Sr2CaCu2O8+delta (Bi2212) shows the presence of nontrivial spin-orbit coupling effects as seen in spin-resolved angle-resolved photoemission spectroscopy data {[}K. Gotlieb et al., Science 362, 1271 (2018)]. Motivated by these observations we consider how the picture of spin-orbit coupling through local inversion symmetry breaking might be observed in cuprate superconductors. Furthermore, we examine two spin-orbit driven effects, the spin-Hall effect and the Edelstein effect, focusing on the details of their realizations within both the normal and superconducting states.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.224512}, author = {Raines, Zachary M. and Allocca, Andrew A. and Galitski, Victor M.} } @article { ISI:000501342800003, title = {Measurement of the 7p P-2(3/2) state branching fractions in Ra+}, journal = {Phys. Rev. A}, volume = {100}, number = {6}, year = {2019}, month = {DEC 6}, pages = {062504}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We report a measurement of the radium ion{\textquoteright}s 7p(2)P(3/2) state branching fractions and improved theoretical calculations. With a single laser-cooled Ra-226(+) ion we measure the P-3/2 branching fractions to the 7s(2)S(1/2) ground state 0.876 78(20), the 6d D-2(5/2) state 0.107 59(10), and the 6d D-2(3/2) state 0.015 63(21).}, issn = {2469-9926}, doi = {10.1103/PhysRevA.100.062504}, author = {Fan, M. and Holliman, C. A. and Porsev, S. G. and Safronova, M. S. and Jayich, A. M.} } @article {ISI:000469016300011, title = {Measurement-induced dynamics and stabilization of spinor-condensate domain walls}, journal = {Phys. Rev. A}, volume = {99}, number = {5}, year = {2019}, month = {MAY 22}, pages = {053612}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Weakly measuring many-body systems and allowing for feedback in real time can simultaneously create and measure new phenomena in quantum systems. We theoretically study the dynamics of a continuously measured two-component Bose-Einstein condensate (BEC) potentially containing a domain wall and focus on the tradeoff between usable information obtained from measurement and quantum backaction. Each weakly measured system yields a measurement record from which we extract real-time dynamics of the domain wall. We show that quantum backaction due to measurement causes two primary effects: domain-wall diffusion and overall heating. The system dynamics and signal-to-noise ratio depend on the choice of measurement observable. We propose a feedback protocol to dynamically create a stable domain wall in the regime where domain walls are unstable, giving a prototype example of Hamiltonian engineering using measurement and feedback.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.99.053612}, author = {Hurst, Hilary M. and Spielman, I. B.} } @article {ISI:000483578600012, title = {Measurements of the branching ratios for 6P(1/2) decays in Ba-138(+)}, journal = {Phys. Rev. A}, volume = {100}, number = {3}, year = {2019}, month = {SEP 3}, pages = {032503}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Measurement of the branching ratios for 6P(1/2) decays to 6S(1/2) and 5D(3/2) in Ba-138(+) are reported with the decay probability from 6P(1/2) to 5D(3/2) measured to be p = 0.268177 +/- (37)(stat)-(20)(sys). This result differs from a recent report by 12 sigma. A detailed account of systematics is given, and the likely source of the discrepancy is identified. The new value of the branching reported here is combined with previous experimental results to give a new estimate of tau = 7.855(10) ns for the 6P(1/2) lifetime. In addition, ratios of matrix elements calculated from theory are combined with experimental results to provide improved theoretical estimates of the 6P(3/2) lifetime and the associated matrix elements.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.100.032503}, author = {Arnold, K. J. and Chanu, S. R. and Kaewuam, R. and Tan, T. R. and Yeo, L. and Zhang, Zhiqiang and Safronova, M. S. and Barrett, M. D.} } @article {ISI:000466709400015, title = {Microcontroller based scanning transfer cavity lock for long-term laser frequency stabilization}, journal = {Rev. Sci. Instrum.}, volume = {90}, number = {4}, year = {2019}, month = {APR}, pages = {043115}, publisher = {AMER INST PHYSICS}, type = {Article}, abstract = {We present a compact all-digital implementation of a scanning transfer cavity lock (STCL) for long-term laser frequency stabilization. An interrupt-driven state machine is employed to realize the STCL with the capability to correct for frequency drifts in the slave laser frequency due to measured changes in the lab environmental conditions. We demonstrate an accuracy of 0.9 MHz for master laser and slave laser wavelengths of 556 nm and 798 nm as an example. The slave laser is also demonstrated to dynamically scan over a wide frequency range while retaining its lock, allowing us to accurately interrogate atomic transitions. Published under license by AIP Publishing.}, issn = {0034-6748}, doi = {10.1063/1.5067266}, author = {Subhankar, S. and Restelli, A. and Wang, Y. and Rolston, S. L. and Porto, J. V.} } @article { ISI:000504926700014, title = {Milliwatt-threshold visible-telecom optical parametric oscillation using silicon nanophotonics}, journal = {Optica}, volume = {6}, number = {12}, year = {2019}, month = {DEC 20}, pages = {1535-1541}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {The on-chip creation of coherent light at visible wavelengths is crucial to field-level deployment of spectroscopy and metrology systems. Although on-chip lasers have been implemented in specific cases, a general solution that is not restricted by limitations of specific gain media has not been reported, to the best of our knowledge. Here, we propose creating visible light from an infrared pump by widely separated optical parametric oscillation (OPO) using silicon nanophotonics. The OPO creates signal and idler light in the 700 nm and 1300 nm bands, respectively, with a 900 nm pump. It operates at a threshold power of (0.9 +/- 0.1) mW, over 50 x smaller than other widely separated microcavity OPO works, which have been reported only in the infrared. This low threshold enables direct pumping without need of an intermediate optical amplifier. We further show how the device design can be modified to generate 780 nm and 1500 nm light with a similar power efficiency. Our nanophotonic OPO shows distinct advantages in power efficiency, operation stability, and device scalability, and is a major advance towards flexible on-chip generation of coherent visible light.}, issn = {2334-2536}, doi = {10.1364/OPTICA.6.001535}, author = {Lu, Xiyuan and Moille, Gregory and Singh, Anshuman and Li, Qing and Westly, Daron A. and Rao, Ashutosh and Yu, Su-Peng and Briles, Travis C. and Papp, Scott B. and Srinivasan, Kartik} } @article { ISI:000502782600002, title = {Momentum-space entanglement after a quench in one-dimensional disordered fermionic systems}, journal = {Phys. Rev. B}, volume = {100}, number = {24}, year = {2019}, month = {DEC 13}, pages = {241108}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We numerically investigate the momentum-space entanglement entropy and entanglement spectrum of the random-dimer model and its generalizations, which circumvent Anderson localization, after a quench in the Hamiltonian parameters. The type of dynamics that occurs depends on whether or not the Fermi level of the initial state is near the energy of the delocalized states present in these models. If the Fermi level of the initial state is near the energy of the delocalized states, we observe an interesting slow logarithmiclike growth of the momentum-space entanglement entropy followed by an eventual saturation. Otherwise, the momentum-space entanglement entropy is found to rapidly saturate. We also find that the momentum-space entanglement spectrum reveals the presence of delocalized states in these models for long times after the quench and the many-body entanglement gap decays logarithmically in time when the Fermi level is near the energy of the delocalized states.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.241108}, author = {Lundgren, Rex and Liu, Fangli and Laurell, Pontus and Fiete, Gregory A.} } @article { ISI:000504573300001, title = {A multiwell applicator for conformal brachytherapy of superficial skin tumors: A simulation study}, journal = {Skin Res. Technol.}, year = {2019}, month = {DEC 27}, publisher = {WILEY}, type = {Article; Early Access}, abstract = {Background Brachytherapy of thin skin tumors using beta particles can protect underlying sensitive structures such as the bone because of the rapid dose falloff of this type of radiation in tissue. The current work describes a skin brachytherapy applicator, based on beta radiation, that can provide the needed cell-killing radiation dose matched to the shape of individual skin tumors. Materials and methods The applicator and its template were fabricated using 3D printing technology. Any clinically approved beta-emitting isotope in the form of a radioactive gel could theoretically be used in this applicator. Monte Carlo simulations were employed to study the capability of the applicator in conforming dose distribution based on the shape of the tumor. Dose profile in the shallow depth, transverse dose profiles at different depths, and the percent depth dose from this applicator were calculated. The radioisotope of choice for our calculations was Yttrium-90 (Y-90). Results Using the proposed applicator, it is possible to create a desired dose profile matching the tumor surface shape. Conclusion The short-range of the beta radiation, together with the dose conforming capability of the applicator, may lead to minimal interactions with the healthy tissue around the skin lesion.}, keywords = {3D printing technology, beta particles, beta-emitting isotopes, brachytherapy, Monte Carlo methods, skin tumor, Y-90}, issn = {0909-752X}, doi = {10.1111/srt.12826}, author = {Pashazadeh, Ali and Robatjazi, Mostafa and Castro, Nathan J. and Friebe, Michael} } @article {14436, title = {Nanoscale Atomic Density Microscopy}, journal = {Phys. Rev. X}, volume = {9}, year = {2019}, month = {Apr}, pages = {021002}, doi = {10.1103/PhysRevX.9.021002}, url = {https://link.aps.org/doi/10.1103/PhysRevX.9.021002}, author = {Subhankar, S. and Wang, Y. and Tsui, T-C. and Rolston, S. L. and Porto, J. V.} } @article {ISI:000485768100009, title = {Narrow-line Cooling and Determination of the Magic Wavelength of Cd}, journal = {Phys. Rev. Lett.}, volume = {123}, number = {11}, year = {2019}, month = {SEP 13}, pages = {113201}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We experimentally and theoretically determine the magic wavelength of the (5s(2))S-1(0) - (5s5p)P-3(0) clock transition of Cd-111 to be 419.88(14) and 420.1(7) nm. To perform Lamb-Dicke spectroscopy of the clock transition, we use narrow-line laser cooling on the S-1(0) - P-3(1) transition to cool the atoms to 6 mu K and load them into an optical lattice. Cadmium is an attractive candidate for optical lattice clocks because it has a small sensitivity to blackbody radiation and its efficient narrow-line cooling mitigates higher order light shifts. We calculate the blackbody shift, including the dynamic correction, to be fractionally 2.83(8) x 10(-16) at 300 K, an order of magnitude smaller than that of Sr and Yb. We also report calculations of the Cd P-1(1) lifetime and the ground state C-6 coefficient.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.113201}, author = {Yamaguchi, A. and Safronova, M. S. and Gibble, K. and Katori, H.} } @article {ISI:000456484300001, title = {Neutral-Atom Wavelength-Compatible 780 nm Single Photons from a Trapped Ion via Quantum Frequency Conversion}, journal = {Phys. Rev. Appl.}, volume = {11}, number = {1}, year = {2019}, month = {JAN 23}, pages = {014044}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The interfacing of quantum platforms via photonic links is a precursor for establishing scalable quantum networks. The connection of different types of quantum memories for hybrid networking requires the overcoming of the disparate photon wavelengths emitted by each quantum memory. Given achievements in quantum information processing with trapped-ion and neutral-atom architectures, a hybrid system with modular interconnectivity is advantageous. Here, we use a trapped Ba-138(+) ion and a periodically poled lithium-niobate (PPLN) waveguide, with a fiber-coupled output, to demonstrate 19\% end-to-end efficient quantum frequency conversion (QFC) of single photons from 493 to 780 nm and use fluorescence of the ion to produce light at the Rb-87 D-2 transition wavelength. To demonstrate the quantum nature of both the unconverted 493 nm photons and the converted photons near 780 nm, we observe strong quantum statics in their respective second-order intensity correlations. This work extends the range of intralaboratory networking between ions and networking between disparate quantum memories.}, issn = {2331-7019}, doi = {10.1103/PhysRevApplied.11.014044}, author = {Siverns, James D. and Hannegan, John and Quraishi, Qudsia} } @article { ISI:000502040000002, title = {Next-generation crossover-free quantum Hall arrays with superconducting interconnections}, journal = {Metrologia}, volume = {56}, number = {6}, year = {2019}, month = {DEC}, pages = {065002}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {This work presents precision measurements of quantized Hall array resistance devices using superconducting, crossover-free and multiple interconnections as well as graphene split contacts. These new techniques successfully eliminate the accumulation of internal resistances and leakage currents that typically occur at interconnections and crossing leads between interconnected devices. As a result, a scalable quantized Hall resistance array is obtained with a nominal value that is as precise and stable as that from single-element quantized Hall resistance standards.}, keywords = {epitaxial graphene, multiple connection, quantized Hall array resistance standards, quantum Hall effect, split contacts, superconducting contacts}, issn = {0026-1394}, doi = {10.1088/1681-7575/ab3ba3}, author = {Kruskopf, Mattias and Rigosi, Albert F. and Panna, Alireza R. and Marzano, Martina and Patel, Dinesh and Jin, Hanbyul and Newell, David B. and Elmquist, Randolph E.} } @article { ISI:000498063400002, title = {Nondestructive Cooling of an Atomic Quantum Register via State-Insensitive Rydberg Interactions}, journal = {Phys. Rev. Lett.}, volume = {123}, number = {21}, year = {2019}, month = {NOV 20}, pages = {213603}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We propose a protocol for sympathetically cooling neutral atoms without destroying the quantum information stored in their internal states. This is achieved by designing state-insensitive Rydberg interactions between the data-carrying atoms and cold auxiliary atoms. The resulting interactions give rise to an effective phonon coupling, which leads to the transfer of heat from the data atoms to the auxiliary atoms, where the latter can be cooled by conventional methods. This can be used to extend the lifetime of quantum storage based on neutral atoms and can have applications for long quantum computations. The protocol can also be modified to realize state-insensitive interactions between the data and the auxiliary atoms but tunable and nontrivial interactions among the data atoms, allowing one to simultaneously cool and simulate a quantum spin model.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.213603}, author = {Belyansky, Ron and Young, Jeremy T. and Bienias, Przemyslaw and Eldredge, Zachary and Kaufman, Adam M. and Zoller, Peter and Gorshkov, V, Alexey} } @article {ISI:000469324000004, title = {Nonlinear waves in an experimentally motivated ring-shaped Bose-Einstein-condensate setup}, journal = {Phys. Rev. A}, volume = {99}, number = {5}, year = {2019}, month = {MAY 29}, pages = {053619}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We systematically construct stationary soliton states in a one-component, two-dimensional, repulsive, Gross-Pitaevskii equation with a ring-shaped targetlike trap similar to the potential used to confine a Bose-Einstein condensate in a recent experiment {[}R. Mathew, A. Kumar, S. Eckel, F. Jendrzejewski, G. K. Campbell, M. Edwards, and E. Tiesinga, Phys. Rev. A 92, 033602 (2015)]. In addition to the ground-state configuration, we identify a wide variety of excited states involving phase jumps (and associated dark solitons) inside the ring. These configurations are obtained from a systematic bifurcation analysis starting from the linear, small atom density, limit. We study the stability and, when unstable, the dynamics of the most basic configurations. Often these lead to vortical dynamics inside the ring persisting over long time scales in our numerical experiments. To illustrate the relevance of the identified states, we showcase how such dark-soliton configurations (even the unstable ones) can be created in laboratory condensates by using phase-imprinting techniques.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.99.053619}, author = {Haberichter, M. and Kevrekidis, P. G. and Carretero-Gonzalez, R. and Edwards, M.} } @article {ISI:000455320600043, title = {Observation of chiral zero mode in inhomogeneous three-dimensional Weyl metamaterials}, journal = {Science}, volume = {363}, number = {6423}, year = {2019}, month = {JAN 11}, pages = {148-151}, publisher = {AMER ASSOC ADVANCEMENT SCIENCE}, type = {Article}, abstract = {Owing to the chirality of Weyl nodes, the Weyl systems can support one-way chiral zero modes under a strong magnetic field, which leads to nonconservation of chiral currents-the so-called chiral anomaly. Although promising for robust transport of optical information, the zero chiral bulk modes have not been observed in photonics. Here we design an inhomogeneous Weyl metamaterial in which a gauge field is generated for the Weyl nodes by engineering the individual unit cells. We experimentally confirm the presence of the gauge field and observe the zero-order chiral Landau level with one-way propagation. Without breaking the time-reversal symmetry, our system provides a route for designing an artificial magnetic field in three-dimensional photonic Weyl systems and may have potential for device applications in photonics.}, issn = {0036-8075}, doi = {10.1126/science.aau7707}, author = {Jia, Hongwei and Zhang, Ruixing and Gao, Wenlong and Guo, Qinghua and Yang, Biao and Hu, Jing and Bi, Yangang and Xiang, Yuanjiang and Liu, Chaoxing and Zhang, Shuang} } @article {ISI:000467042000002, title = {Observation of Many-Body Localization in a One-Dimensional System with a Single-Particle Mobility Edge}, journal = {Phys. Rev. Lett.}, volume = {122}, number = {17}, year = {2019}, month = {MAY 3}, pages = {170403}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We experimentally study many-body localization (MBL) with ultracold atoms in a weak onedimensional quasiperiodic potential, which in the noninteracting limit exhibits an intermediate phase that is characterized by a mobility edge. We measure the time evolution of an initial charge density wave after a quench and analyze the corresponding relaxation exponents. We find clear signatures of MBL when the corresponding noninteracting model is deep in the localized phase. We also critically compare and contrast our results with those from a tight-binding Aubry-Andre model, which does not exhibit a singleparticle intermediate phase, in order to identify signatures of a potential many-body intermediate phase.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.122.170403}, author = {Kohlert, Thomas and Scherg, Sebastian and Li, Xiao and Lueschen, Henrik P. and S. Das Sarma and Bloch, Immanuel and Aidelsburger, Monika} } @article {ISI:000461126600036, title = {Optical clock comparison for Lorentz symmetry testing}, journal = {Nature}, volume = {567}, number = {7747}, year = {2019}, month = {MAR 14}, pages = {204+}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {Questioning basic assumptions about the structure of space and time has greatly enhanced our understanding of nature. State-of-the-art atomic clocks(1-3) make it possible to precisely test fundamental symmetry properties of spacetime and search for physics beyond the standard model at low energies of just a few electronvolts(4). Modern tests of Einstein{\textquoteright}s theory of relativity try to measure so-far-undetected violations of Lorentz symmetry(5); accurately comparing the frequencies of optical clocks is a promising route to further improving such tests(6). Here we experimentally demonstrate agreement between two single-ion optical clocks at the 10(-18) level, directly validating their uncertainty budgets, over a six-month comparison period. The ytterbium ions of the two clocks are confined in separate ion traps with quantization axes aligned along non-parallel directions. Hypothetical Lorentz symmetry violations(5-7) would lead to periodic modulations of the frequency offset as the Earth rotates and orbits the Sun. From the absence of such modulations at the 10(-19) level we deduce stringent limits of the order of 10(-21) on Lorentz symmetry violation parameters for electrons, improving previous limits(8-10) by two orders of magnitude. Such levels of precision will be essential for low-energy tests of future quantum gravity theories describing dynamics at the Planck scale(4), which are expected to predict the magnitude of residual symmetry violations.}, issn = {0028-0836}, doi = {10.1038/s41586-019-0972-2}, author = {Sanner, Christian and Huntemann, Nils and Lange, Richard and Tamm, Christian and Peik, Ekkehard and Safronova, Marianna S. and Porsev, Sergey G.} } @article {ISI:000462898900011, title = {Optical response of Luttinger semimetals in the normal and superconducting states}, journal = {Phys. Rev. B}, volume = {99}, number = {12}, year = {2019}, month = {MAR 25}, pages = {125146}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We investigate the optical response properties of three-dimensional Luttinger semimetals with the Fermi energy close to a quadratic band touching point. In particular, in order to address recent experiments on the spectroscopy of pyrochlore iridates and half-Heusler superconductors, we derive expressions for the optical conductivity in both the normal and general superconducting states in the linear response regime within the random phase approximation. The response functions can be decomposed into contributions from intraband and interband transitions, the latter comprising a genuine signature of the quadratic band touching point. We demonstrate the importance of interband transitions in the optical response in the normal state both in the homogeneous and quasistatic limit. Our analysis reveals a factorization property of the homogeneous conductivity in the spatially anisotropic case and the divergence of the conductivity for strong spatial anisotropy. In the quasistatic limit, the response is dominated by interband transitions and significantly different from systems with a single parabolic band. As an applications of the formalism in the superconducting state we compute the optical conductivity and superfluid density for the s-wave singlet superconducting case for both finite and vanishing chemical potential.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.125146}, author = {Boettcher, Igor} } @article {ISI:000473132200039, title = {Orbital-flop Induced Magnetoresistance Anisotropy in Rare Earth Monopnictide CeSb}, journal = {Nat. Commun.}, volume = {10}, year = {2019}, month = {JUN 28}, pages = {2875}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {The charge and spin of the electrons in solids have been extensively exploited in electronic devices and in the development of spintronics. Another attribute of electrons-their orbital nature-is attracting growing interest for understanding exotic phenomena and in creating the next-generation of quantum devices such as orbital qubits. Here, we report on orbital-flop induced magnetoresistance anisotropy in CeSb. In the low temperature high magnetic-field driven ferromagnetic state, a series of additional minima appear in the angle-dependent magnetoresistance. These minima arise from the anisotropic magnetization originating from orbital-flops and from the enhanced electron scattering from magnetic multidomains formed around the first-order orbital-flop transition. The measured magnetization anisotropy can be accounted for with a phenomenological model involving orbital-flops and a spin-valve-like structure is used to demonstrate the viable utilization of orbital-flop phenomenon. Our results showcase a contribution of orbital behavior in the emergence of intriguing phenomena.}, issn = {2041-1723}, doi = {10.1038/s41467-019-10624-z}, author = {Xu, Jing and Wu, Fengcheng and Bao, Jin-Ke and Han, Fei and Xiao, Zhi-Li and Martin, Ivar and Lyu, Yang-Yang and Wang, Yong-Lei and Chung, Duck Young and Li, Mingda and Zhang, Wei and Pearson, John E. and Jiang, Jidong S. and Kanatzidis, Mercouri G. and Kwok, Wai-Kwong} } @article {ISI:000456825600004, title = {Origin of spectral brightness variations in InAs/InP quantum dot telecom single photon emitters}, journal = {J. Vac. Sci. Technol. B}, volume = {37}, number = {1}, year = {2019}, month = {JAN}, pages = {011202}, publisher = {A V S AMER INST PHYSICS}, type = {Article}, abstract = {Long-distance quantum communication relies on the ability to efficiently generate and prepare single photons at telecom wavelengths. Low-density InAs quantum dots on InP surfaces are grown in a molecular beam epitaxy system using a modified Stranski-Krastanov growth paradigm. This material is a source of bright and indistinguishable single photons in the 1.3 mu m telecom band. Here, the exploration of the growth parameters is presented as a phase diagram, while low-temperature photoluminescence and atomic resolution images are presented to correlate structure and spectral performance. This work identifies specific stacking faults and V-shaped defects that are likely causes of the observed low brightness emission at 1.55 mu m telecom wavelengths. The different locations of the imaged defects suggest possible guidance for future development of InAs/InP single photon sources for c-band, 1.55 mu m wavelength telecommunication systems.}, issn = {1071-1023}, doi = {10.1116/1.5042540}, author = {Richardson, Christopher J. K. and Leavitt, Richard P. and Kim, Je-Hyung and Waks, Edo and Arslan, Ilke and Arey, Bruce} } @article {14571, title = {Parallel entangling operations on a universal ion-trap quantum computer}, journal = {Nature}, year = {2019}, doi = {10.1038/s41586-019-1427-5}, url = {https://www.nature.com/articles/s41586-019-1427-5}, author = {Figgatt, Caroline and Ostrander, A and Linke, Norbert M. and Landsman, Kevin A. and Zhu, D and Maslov, Dmitri and Christopher Monroe} } @article {14286, title = {Parametric Heating in a 2D Periodically Driven Bosonic System: Beyond the Weakly Interacting Regime}, journal = {Physical Review X}, volume = {9}, year = {2019}, pages = {011047}, author = {Boulier, T and Maslek, J and Bukov, M and Bracamontes, C and Magnan, E and Lellouch, S and Demler, E and Goldman, N and Porto, J V} } @article {ISI:000461066200001, title = {Parametric Heating in a 2D Periodically Driven Bosonic System: Beyond the Weakly Interacting Regime}, journal = {Phys. Rev. X}, volume = {9}, number = {1}, year = {2019}, month = {MAR 13}, pages = {011047}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We experimentally investigate the effects of parametric instabilities on the short-time heating process of periodically driven bosons in 2D optical lattices with a continuous transverse (tube) degree of freedom. We analyze three types of periodic drives: (i) linear along the x-lattice direction only, (ii) linear along the lattice diagonal, and (iii) circular in the lattice plane. In all cases, we demonstrate that the Bose-Einstein condensate (BEC) decay is dominated by the emergence of unstable Bogoliubov modes, rather than scattering in higher Floquet bands, in agreement with recent theoretical predictions. The observed BEC depletion rates are much higher when shaking along both the x and y directions, as opposed to only x or only y. We also report an explosion of the decay rates at large drive amplitudes and suggest a phenomenological description beyond the Bogoliubov theory. In this strongly coupled regime, circular drives heat faster than diagonal drives, which illustrates the nontrivial dependence of the heating on the choice of drive.}, issn = {2160-3308}, doi = {10.1103/PhysRevX.9.011047}, author = {Boulier, T. and Maslek, J. and Bukov, M. and Bracamontes, C. and Magnan, E. and Lellouch, S. and Demler, E. and Goldman, N. and Porto, V, J.} } @article {ISI:000473018000001, title = {Parton construction of particle-hole-conjugate Read-Rezayi parafermion fractional quantum Hall states and beyond}, journal = {Phys. Rev. B}, volume = {99}, number = {24}, year = {2019}, month = {JUN 19}, pages = {241108}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The Read-Rezayi (RR) parafermion states form a series of exotic non-Abelian fractional quantum Hall (FQH) states at filling. = k/(k + 2). Computationally, the wave functions of these states are prohibitively expensive to generate for large systems. We introduce a series of parton states, denoted (\$2) over bar (k)1(k+1), and show that they lie in the same universality classes as the particle-hole-conjugate RR ({{\textquoteright}{\textquoteright}}anti-RR{{\textquoteright}{\textquoteright}}) states. Our analytical results imply that a {[}U(1)(k+1) xU(2k)(-1)]/{[}SU(k)(-2) xU(1)(-1)] coset conformal field theory describes the edge excitations of the (2) over bar (k)1(k+1) state, suggesting nontrivial dualities with respect to previously known descriptions. The parton construction allows wave functions in anti-RR phases to be generated for hundreds of particles. We further propose the parton sequence (n) over bar(2) over bar (4), with n = 1, 2, 3, to describe the FQH states observed at nu= 2 + 1/2, 2 + 2/5, and 2 + 3/8.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.241108}, author = {Balram, Ajit C. and Barkeshli, Maissam and Rudner, Mark S.} } @article {14481, title = {Perfect Andreev reflection due to the Klein paradox in a topological superconducting state}, journal = {Nature}, volume = {570}, year = {2019}, pages = {344{\textendash}348}, abstract = {In 1928, Dirac proposed a wave equation to describe relativistic electrons1. Shortly afterwards, Klein solved a simple potential step problem for the Dirac equation and encountered an apparent paradox: the potential barrier becomes transparent when its height is larger than the electron energy. For massless particles, backscattering is completely forbidden in Klein tunnelling, leading to perfect transmission through any potential barrier2,3. The recent advent of condensed-matter systems with Dirac-like excitations, such as graphene and topological insulators, has opened up the possibility of observing Klein tunnelling experimentally4{\textendash}6. In the surface states of topological insulators, fermions are bound by spin{\textendash}momentum locking and are thus immune from backscattering, which is prohibited by time-reversal symmetry. Here we report the observation of perfect Andreev reflection in point-contact spectroscopy{\textendash}-a clear signature of Klein tunnelling and a manifestation of the underlying {\textquoteleft}relativistic{\textquoteright}physics of a proximity-induced superconducting state in a topological Kondo insulator. Our findings shed light on a previously overlooked aspect of topological superconductivity and can serve as the basis for a unique family of spintronic and superconducting devices, the interface transport phenomena of which are completely governed by their helical topological states.

}, isbn = {1476-4687}, doi = {10.1038/s41586-019-1305-1}, url = {https://doi.org/10.1038/s41586-019-1305-1}, author = {Lee, Seunghun and Stanev, Valentin and Zhang, Xiaohang and Stasak, Drew and Flowers, Jack and Higgins, Joshua S. and Dai, Sheng and Blum, Thomas and Pan, Xiaoqing and Yakovenko, Victor M. and Paglione, Johnpierre and Greene, Richard L. and Galitski, Victor and Takeuchi, Ichiro} } @article {ISI:000463889200003, title = {Phonon-induced giant linear-in-T resistivity in magic angle twisted bilayer graphene: Ordinary strangeness and exotic superconductivity}, journal = {Phys. Rev. B}, volume = {99}, number = {16}, year = {2019}, month = {APR 9}, pages = {165112}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study the effect of electron-acoustic phonon interactions in twisted bilayer graphene on resistivity in the high-temperature transport and superconductivity in the low-temperature phase diagram. We theoretically show that twisted bilayer graphene should have an enhanced and strongly twist-angle dependent linear-in-temperature resistivity in the metallic regime with the resistivity magnitude increasing as the twist angle approaches the magic angle. The slope of the resistivity versus temperature could approach one hundred ohm per kelvin with a strong angle dependence, but with a rather weak dependence on the carrier density. This higher-temperature density-independent linear-in-T resistivity crosses over to a T-4 dependence at a low density-dependent characteristic temperature, becoming unimportant at low temperatures. This angle-tuned resistivity enhancement arises from the huge increase in the effective electron-acoustic phonon coupling in the system due to the suppression of graphene Fermi velocity induced by the flat-band condition in the moire superlattice system. Our calculated temperature dependence is reminiscent of the so-called {\textquoteleft}{\textquoteleft}strange metal{{\textquoteright}{\textquoteright}} transport behavior except that it is arising from the ordinary electron-phonon coupling in a rather unusual parameter space due to the generic moire flat-band structure of twisted bilayer graphene. We also show that the same enhanced electron-acoustic phonon coupling also mediates effective attractive interactions in s, p, d, and f pairing channels with a theoretical superconducting transition temperature on the order of similar to 5 K near magic angle. The fact that ordinary acoustic phonons can produce exotic non-s-wave superconducting pairing arises from the unusual symmetries of the system.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.165112}, author = {Wu, Fengcheng and Hwang, Euyheon and S. Das Sarma} } @article {ISI:000479005400008, title = {Photon Pair Condensation by Engineered Dissipation}, journal = {Phys. Rev. Lett.}, volume = {123}, number = {6}, year = {2019}, month = {AUG 6}, pages = {063602}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Dissipation can usually induce detrimental decoherence in a quantum system. However, engineered dissipation can be used to prepare and stabilize coherent quantum many-body states. Here, we show that, by engineering dissipators containing photon pair operators, one can stabilize an exotic dark state, which is a condensate of photon pairs with a phase-nematic order. In this system, the usual superfluid order parameter, i.e., single-photon correlation, is absent, while the photon pair correlation exhibits long-range order. Although the dark state is not unique due to multiple parity sectors, we devise an additional type of dissipators to stabilize the dark state in a particular parity sector via a diffusive annihilation process which obeys Glauber dynamics in an Ising model. Furthermore, we propose an implementation of these photon pair dissipators in circuit-QED architecture.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.063602}, author = {Cian, Ze-Pei and Zhu, Guanyu and Chu, Su-Kuan and Seif, Alireza and DeGottardi, Wade and Jiang, Liang and Hafezi, Mohammad} } @article {ISI:000477918500001, title = {Photonic Anomalous Quantum Hall Effect}, journal = {Phys. Rev. Lett.}, volume = {123}, number = {4}, year = {2019}, month = {JUL 23}, pages = {043201}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We experimentally realize a photonic analogue of the anomalous quantum Hall insulator using a two-dimensional (2D) array of coupled ring resonators. Similar to the Haldane model, our 2D array is translation invariant, has a zero net gauge flux threading the lattice, and exploits next-nearest neighbor couplings to achieve a topologically nontrivial band gap. Using direct imaging and on-chip transmission measurements, we show that the band gap hosts topologically robust edge states. We demonstrate a topological phase transition to a conventional insulator by frequency detuning the ring resonators and thereby breaking the inversion symmetry of the lattice. Furthermore, the clockwise or the counterclockwise circulation of photons in the ring resonators constitutes a pseudospin degree of freedom. The two pseudospins acquire opposite hopping phases, and their respective edge states propagate in opposite directions. These results are promising for the development of robust reconfigurable integrated nanophotonic devices for applications in classical and quantum information processing.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.043201}, author = {Mittal, Sunil and Orre, Venkata Vikram and Leykam, Daniel and Chong, Y. D. and Hafezi, Mohammad} } @article {14466, title = {Photonic quadrupole topological phases}, journal = {Nature Photonics}, year = {2019}, abstract = {The topological phases of matter are characterized using the Berry phase, a geometrical phase associated with the energy-momentum band structure. The quantization of the Berry phase and the associated wavefunction polarization manifest as remarkably robust physical observables, such as quantized Hall conductivity and disorder-insensitive photonic transport1{\textendash}5. Recently, a novel class of topological phases, called higher-order topological phases, were proposed by generalizing the fundamental relationship between the Berry phase and quantized polarization, from dipole to multipole moments6{\textendash}8. Here, we demonstrate photonic realization of the quantized quadrupole topological phase, using silicon photonics. In our two-dimensional second-order topological phase, we show that the quantization of the bulk quadrupole moment manifests as topologically robust zero-dimensional corner states. We contrast these topological states against topologically trivial corner states in a system without bulk quadrupole moment, where we observe no robustness. Our photonic platform could enable the development of robust on-chip classical and quantum optical devices with higher-order topological protection.

}, isbn = {1749-4893}, doi = {10.1038/s41566-019-0452-0}, url = {https://doi.org/10.1038/s41566-019-0452-0}, author = {Mittal, Sunil and Orre, Venkata Vikram and Zhu, Guanyu and Gorlach, Maxim A. and Poddubny, Alexander and Hafezi, Mohammad} } @article { ISI:000492332900006, title = {Polarizability assessments of ion-based optical clocks}, journal = {Phys. Rev. A}, volume = {100}, number = {4}, year = {2019}, month = {OCT 24}, pages = {043418}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {It is shown that the dynamic differential scalar polarizability of the S-1/2 - D-5/2 transition in Ba-138(+) can be determined to an inaccuracy below 0.5\% across a wide wavelength range (lambda > 700 nm). This can be achieved using measurements for which accurate determination of laser intensity is not required, and most of the required measurements are already in the literature. Measurement of a laser-induced ac-Stark shift of the clock transition would then provide an in situ measurement of the laser{\textquoteright}s intensity to the same 0.5\% level of inaccuracy, which is not easily achieved by other means. This would allow accurate polarizability measurements for clock transitions in other ions, through comparison with Ba-138(+). The approach would be equally applicable to Sr+ and Ca+, with the latter being immediately applicable to Al+/Ca+ quantum logic clocks.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.100.043418}, author = {Barrett, M. D. and Arnold, K. J. and Safronova, M. S.} } @article { ISI:000488249400003, title = {Polynomial time algorithms for estimating spectra of adiabatic Hamiltonians}, journal = {Phys. Rev. A}, volume = {100}, number = {3}, year = {2019}, month = {SEP 30}, pages = {032336}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Much research regarding quantum adiabatic optimization has focused on stoquastic Hamiltonians with Hamming-symmetric potentials, such as the well-studied {\textquoteleft}{\textquoteleft}spike{{\textquoteright}{\textquoteright}} example. Due to the large amount of symmetry in these potentials such problems are readily open to analysis both analytically and computationally. However, more realistic potentials do not have such a high degree of symmetry and may have many local minima Here we present a somewhat more realistic class of problems consisting of many individually Hamming-symmetric potential wells. For two or three such wells we demonstrate that such a problem can be solved exactly in time polynomial in the number of qubits and wells. For greater than three wells, we present a tight-binding approach with which to efficiently analyze the performance of such Hamiltonians in an adiabatic computation. We provide several basic examples designed to highlight the usefulness of this toy model and to give insight into using the tight-binding approach to examining it, including (1) an adiabatic unstructured search with a transverse field driver and a prior guess to the marked item and (2) a scheme for adiabatically simulating the ground states of small collections of strongly interacting spins, with an explicit demonstration for an Ising-model Hamiltonian.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.100.032336}, author = {Bringewatt, Jacob and Dorland, William and Jordan, Stephen P.} } @article {ISI:000454776000002, title = {Possible Hundredfold Enhancement in the Direct Magnetic Coupling of a Single-Atom Electron Spin to a Circuit Resonator}, journal = {Phys. Rev. Appl.}, volume = {11}, number = {1}, year = {2019}, month = {JAN 2}, pages = {014001}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We report on the challenges and limitations of direct coupling of the magnetic field from a circuit resonator to an electron spin bound to a donor potential. We propose a device consisting of a trilayer lumped-element superconducting resonator and a single donor implanted in enriched Si-28. The resonator impedance is significantly smaller than the practically achievable limit obtained with prevalent coplanar resonators. Furthermore, the resonator includes a nanoscale spiral inductor to spatially focus the magnetic field from the photons at the location of the implanted donor. The design promises an increase of approximately 2 orders of magnitude in the local magnetic field, and thus the spin-to-photon coupling rate g, compared with the estimated rate of coupling to the magnetic field of coplanar transmission line resonators. We show that by use of niobium (aluminum) as the resonator{\textquoteright}s superconductor and a single phosphorous (bismuth) atom as the donor, a coupling rate of g/2 pi = 0.24 MHz (0.39 MHz) can be achieved in the single-photon regime. For this hybrid cavity-quantum-electrodynamic system, such enhancement in g is sufficient to enter the strong-coupling regime.}, issn = {2331-7019}, doi = {10.1103/PhysRevApplied.11.014001}, author = {Sarabi, Bahman and Huang, Peihao and Zimmerman, Neil M.} } @conference {ISI:000481657400006, title = {A post-processing-free single-photon random number generator with ultra-low latency}, booktitle = {ADVANCES IN PHOTONICS OF QUANTUM COMPUTING, MEMORY, AND COMMUNICATION XII}, series = {Proceedings of SPIE}, volume = {10933}, year = {2019}, note = {Conference on Advances in Photonics of Quantum Computing, Memory, and Communication XII, San Francisco, CA, FEB 05-07, 2019}, pages = {109330F}, publisher = {SPIE}, organization = {SPIE}, type = {Proceedings Paper}, abstract = {The low-latency requirements of a loophole-free Bell test prohibit time-consuming post-processing steps that arc often used to improve the statistical quality of a physical random number generator (RNG). Here we demonstrate a post-processing-free RNG that produces a random bit within 2.4(2) ns of an input trigger. We use the Allan variance as a tool for characterizing non-idealities in the RNG and designing a feedback mechanism to account for and correct long-term drift. The impact of the feedback on the predictability of the output is less than 6.4 x 10(7), and results in a system capable of 24 hour operation with output that is statistically indistinguishable from a balanced Bernoulli process.}, keywords = {Bell test, low latency, Quantum Information, random number generator, single-photon}, isbn = {978-1-5106-2509-9}, issn = {0277-786X}, doi = {10.1117/12.2514855}, author = {Wayne, Michael A. and Migdall, Alan L. and Levine, Zachary H. and Bienfang, Joshua C.}, editor = {Hemmer, PR and Migdall, AL and UlHasan, Z} } @article { ISI:000499991300005, title = {Precision Test of the Limits to Universality in Few-Body Physics}, journal = {Phys. Rev. Lett.}, volume = {123}, number = {23}, year = {2019}, month = {DEC 2}, pages = {233402}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We perform precise studies of two- and three-body interactions near an intermediate-strength Feshbach resonance in K-39 at 33.5820(14) G. Precise measurement of dimer binding energies, spanning three orders of magnitude, enables the construction of a complete two-body coupled-channel model for determination of the scattering lengths with an unprecedented low uncertainty. Utilizing an accurate scattering length map, we measure the precise location of the Efimov ground state to test van der Waals universality. Precise control of the sample{\textquoteright}s temperature and density ensures that systematic effects on the Efimov trimer state are well understood. We measure the ground Efimov resonance location to be at -14.05(17) times the van der Waals length r(vdW), significantly deviating from the value of -9.7r(vdW) predicted by van der Waals universality. We find that a refined multichannel three-body model, built on our measurement of two-body physics, can account for this difference and even successfully predict the Efimov inelasticity parameter eta.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.233402}, author = {Chapurin, Roman and Xie, Xin and Van de Graaff, Michael J. and Popowski, Jared S. and D{\textquoteright}Incao, Jose P. and Julienne, Paul S. and Ye, Jun and Cornell, Eric A.} } @article {ISI:000473540500004, title = {Prediction of a Non-Abelian Fractional Quantum Hall State with f-Wave Pairing of Composite Fermions in Wide Quantum Wells}, journal = {Phys. Rev. Lett.}, volume = {123}, number = {1}, year = {2019}, month = {JUL 2}, pages = {016802}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We theoretically investigate the nature of the state at the quarter filled lowest Landau level and predict that, as the quantum well width is increased, a transition occurs from the composite fermion Fermi sea into a novel non-Abelian fractional quantum Hall state that is topologically equivalent to f-wave pairing of composite fermions. This state is topologically distinct from the familiar p-wave paired Pfaffian state. We compare our calculated phase diagram with experiments and make predictions for many observable quantities.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.016802}, author = {Faugno, W. N. and Balram, Ajit C. and Barkeshli, Maissam and Jain, J. K.} } @article {ISI:000474369000008, title = {Presence versus absence of end-to-end nonlocal conductance correlations in Majorana nanowires: Majorana bound states versus Andreev bound states}, journal = {Phys. Rev. B}, volume = {100}, number = {4}, year = {2019}, month = {JUL 3}, pages = {045302}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {By calculating the differential tunneling conductance spectra from the two ends of a Majorana nanowire with a quantum dot embedded at one end, we establish that a careful examination of the nonlocal correlations of the zero-bias conductance peaks, as measured separately from the two ends of the wire, can distinguish between topological Majorana bound states and trivial Andreev bound states. In particular, there will be identical correlated zero-bias peaks from both ends for Majorana bound states, and thus the presence of correlated zero-bias conductance from the two wire ends could imply the presence of topological Majorana zero modes in the system. On the contrary, there will not be identical correlated zero-bias peaks from both ends for Andreev bound states, so the absence of correlated zero-bias conductance from the two wire ends implies the absence of topological Majorana zero modes in the system. We present detailed results for the calculated conductance, energy spectra, and wave functions for different chemical potentials at the same magnetic field values to motivate end-to-end conductance correlation measurements in Majorana nanowires.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.045302}, author = {Lai, Yi-Hua and Sau, Jay D. and S. Das Sarma} } @article {ISI:000485202800004, title = {Probing Ground-State Phase Transitions through Quench Dynamics}, journal = {Phys. Rev. Lett.}, volume = {123}, number = {11}, year = {2019}, month = {SEP 11}, pages = {115701}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The study of quantum phase transitions requires the preparation of a many-body system near its ground state, a challenging task for many experimental systems. The measurement of quench dynamics, on the other hand, is now a routine practice in most cold atom platforms. Here we show that quintessential ingredients of quantum phase transitions can be probed directly with quench dynamics in integrable and nearly integrable systems. As a paradigmatic example, we study global quench dynamics in a transverse-field Ising model with either short-range or long-range interactions. When the model is integrable, we discover a new dynamical critical point with a nonanalytic signature in the short-range correlators. The location of the dynamical critical point matches that of the quantum critical point and can be identified using a finite-time scaling method. We extend this scaling picture to systems near integrability and demonstrate the continued existence of a dynamical critical point detectable at prethermal timescales. We quantify the difference in the locations of the dynamical and quantum critical points away from (but near) integrability. Thus, we demonstrate that this method can be used to approximately locate the quantum critical point near integrability. The scaling method is also relevant to experiments with finite time and system size, and our predictions are testable in near-term experiments with trapped ions and Rydberg atoms.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.115701}, author = {Titum, Paraj and Iosue, Joseph T. and Garrison, James R. and Gorshkov, Alexey V. and Gong, Zhe-Xuan} } @article { ISI:000499482200011, title = {Probing Trions at Chemically Tailored Trapping Defects}, journal = {ACS Central Sci.}, volume = {5}, number = {11}, year = {2019}, month = {NOV 27}, pages = {1786-1794}, publisher = {AMER CHEMICAL SOC}, type = {Article}, abstract = {Trions, charged excitons that are reminiscent of hydrogen and positronium ions, have been intensively studied for energy harvesting, light-emitting diodes, lasing, and quantum computing applications because of their inherent connection with electron spin and dark excitons. However, these quasi-particles are typically present as a minority species at room temperature making it difficult for quantitative experimental measurements. Here, we show that by chemically engineering the well depth of sp(3) quantum defects through a series of alkyl functional groups covalently attached to semiconducting carbon nanotube hosts, trions can be efficiently generated and localized at the trapping chemical defects. The exciton-electron binding energy of the trapped trion approaches 119 meV, which more than doubles that of {\textquoteleft}{\textquoteleft}free{{\textquoteright}{\textquoteright}} trions in the same host material (54 meV) and other nanoscale systems (2-45 meV). Magnetoluminescence spectroscopy suggests the absence of dark states in the energetic vicinity of trapped trions. Unexpectedly, the trapped trions are approximately 7.3-fold brighter than the brightest previously reported and 16 times as bright as native nanotube excitons, with a photoluminescence lifetime that is more than 100 times larger than that of free trions. These intriguing observations are understood by an efficient conversion of dark excitons to bright trions at the defect sites. This work makes trions synthetically accessible and uncovers the rich photophysics of these tricarrier quasi-particles, which may find broad implications in bioimaging, chemical sensing, energy harvesting, and light emitting in the short-wave infrared.}, issn = {2374-7943}, doi = {10.1021/acscentsci.9b00707}, author = {Kwon, Hyejin and Kim, Mijin and Nutz, Manuel and Hartmann, Nicolai F. and Perrin, Vivien and Meany, Brendan and Hofmann, Matthias S. and Clark, Charles W. and Htoon, Han and Doorn, Stephen K. and Hoegele, Alexander and Wang, YuHuang} } @article {ISI:000462932400012, title = {Proposal for Measuring the Parity Anomaly in a Topological Superconductor Ring}, journal = {Phys. Rev. Lett.}, volume = {122}, number = {11}, year = {2019}, month = {MAR 22}, pages = {117001}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {A topological superconductor ring is uniquely characterized by a switch in the ground state fermion number parity upon insertion of one superconducting flux quantum-a direct consequence of the topological {\textquoteleft}{\textquoteleft}parity anomaly.{{\textquoteright}{\textquoteright}} Despite the many other tantalizing signatures and applications of topological superconductors, this fundamental, defining property remains to be observed experimentally. Here we propose definitive detection of the fermion parity switch from the charging energy, temperature, and tunnel barrier dependence of the flux periodicity of two-terminal conductance of a floating superconductor ring. We extend the Ambegaokar-Eckern-Schon formalism for superconductors with a Coulomb charging energy to establish new explicit relationships between thermodynamic and transport properties of such a ring and the topological invariant of the superconductor. Crucially, we show that the topological contribution to the conductance oscillations can be isolated from Aharonov-Bohm oscillations of nontopological origin by their different dependence on the charging energy or barrier transparency.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.122.117001}, author = {Liu, Chun-Xiao and Cole, William S. and Sau, Jay D.} } @article { ISI:000496588600002, title = {Protocol for Reading Out Majorana Vortex Qubits and Testing Non-Abelian Statistics}, journal = {Phys. Rev. Appl.}, volume = {12}, number = {5}, year = {2019}, month = {NOV 14}, pages = {054035}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The successful testing of non-Abelian statistics not only serves as a milestone in fundamental physics but also provides a quantum-gate operation in topological quantum computation. An accurate and efficient readout scheme of a topological qubit is an essential step toward the experimental confirmation of non-Abelian statistics. In the current work, we propose a protocol to read out the quantum state of a Majorana vortex qubit on a topological superconductor island. The protocol consists of four Majorana zero modes trapped in spatially well-separated vortex cores on the two-dimensional surface of a Coulomb blockaded topological superconductor. Our proposed measurement is implemented by a pair of weakly coupled Majorana modes separately in touch with two normal-metal leads and the readout is realized by observing the conductance-peak location in terms of the gate voltage. Using this protocol, we can further test the non-Abelian statistics of Majorana zero modes in the two-dimensional platform. A successful readout of a Majorana qubit is a crucial step toward the future application of topological quantum computation. In addition, this Coulomb-blockaded setup can distinguish Majorana zero modes from Caroli-de Gennes-Matricon modes in vortex cores.}, issn = {2331-7019}, doi = {10.1103/PhysRevApplied.12.054035}, author = {Liu, Chun-Xiao and Liu, Dong E. and Zhang, Fu-Chun and Chiu, Ching-Kai} } @article {ISI:000471060400001, title = {pyLLE: A Fast and User Friendly Lugiato-Lefever Equation Solver}, journal = {J. Res. Natl. Inst. Stand. Technol.}, volume = {124}, year = {2019}, month = {MAY 24}, pages = {012}, publisher = {NATL INST STANDARDS \& TECHNOLOGY-NIST}, type = {Article}, keywords = {Julia, micro-combs, non-linear optics, python}, issn = {2165-7254}, doi = {10.6028/jres.124.012}, author = {Moille, Gregory and Li, Qing and Lu, Xiyuan and Srinivasan, Kartik} } @article {ISI:000484374000020, title = {Quantum electrodynamics of a superconductor-insulator phase transition}, journal = {Nat. Phys.}, volume = {15}, number = {9}, year = {2019}, month = {SEP}, pages = {930+}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {A chain of Josephson junctions represents one of the simplest many-body models undergoing a superconductor-insulator quantum phase transition(1,2). Apart from zero resistance, the superconducting state is necessarily accompanied by a sound-like mode due to collective oscillations of the phase of the complex-valued order parameter(3,4). Little is known about the fate of this mode on entering the insulating state, where the order parameter{\textquoteright}s amplitude remains non-zero, but the phase ordering is {\textquoteleft}melted{\textquoteright} by quantum fluctuations(5). Here, we show that the phase mode survives far into the insulating regime, such that megaohm-resistance chains can carry gigahertz-frequency alternating currents as nearly ideal superconductors. The insulator reveals itself through interaction-induced broadening and random frequency shifts of collective mode resonances. Our spectroscopic experiment puts forward the problem of quantum electrodynamics of a Bose glass for both theory and experiments(6-8). By pushing the chain parameters deeper into the insulating state, we achieved a wave impedance of the phase mode exceeding the predicted critical value by an order of magnitude(9-14). The effective fine structure constant of such a one-dimensional electromagnetic vacuum exceeds unity, promising transformative applications to quantum science and technology.}, issn = {1745-2473}, doi = {10.1038/s41567-019-0553-1}, author = {Kuzmin, R. and Mencia, R. and Grabon, N. and Mehta, N. and Lin, Y-H and Manucharyan, V. E.} } @article {ISI:000468373300008, title = {Quantum frequency conversion of a quantum dot single-photon source on a nanophotonic chip}, journal = {Optica}, volume = {6}, number = {5}, year = {2019}, month = {MAY 20}, pages = {563-569}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {Single self-assembled InAs/GaAs quantum dots are promising bright sources of indistinguishable photons for quantum information science. However, their distribution in emission wavelength, due to inhomogeneous broadening inherent to their growth, has limited the ability to create multiple identical sources. Quantum frequency conversion can overcome this issue, particularly if implemented using scalable chip-integrated technologies. Here, we report the first demonstration to our knowledge of quantum frequency conversion of a quantum dot single-photon source on a silicon nanophotonic chip. Single photons from a quantum dot in a micropillar cavity are shifted in wavelength with an on-chip conversion efficiency approximate to 12\%, limited by the linewidth of the quantum dot photons. The intensity auto-correlation function g((2)) (tau) for the frequency-converted light is antibunched with g((2)) (0) = 0.290 +/- 0.030, compared to the before-conversion value g((2)) (0) = 0.080 +/- 0.003. We demonstrate the suitability of our frequency-conversion interface as a resource for quantum dot sources by characterizing its effectiveness across a wide span of input wavelengths (840-980 nm) and its ability to achieve tunable wavelength shifts difficult to obtain by other approaches. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {2334-2536}, doi = {10.1364/OPTICA.6.000563}, author = {Singh, Anshuman and Li, Qing and Liu, Shunfa and Yu, Ying and Lu, Xiyuan and Schneider, Christian and Hoefling, Sven and Lawall, John and Verma, Varun and Mirin, Richard and Nam, Sae Woo and Liu, Jin and Srinivasan, Kartik} } @article {ISI:000485187000003, title = {Quantum information scrambling through a high-complexity operator mapping}, journal = {Phys. Rev. A}, volume = {100}, number = {3}, year = {2019}, month = {SEP 6}, pages = {032309}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Quantum information scrambling has attracted much attention amid the effort to reconcile the conflict between quantum-mechanical unitarity and the thermalization irreversibility in many-body systems. Here we propose an unconventional mechanism to generate quantum information scrambling through a high-complexity mapping from logical to physical degrees-of-freedom that hides the logical information into nonseparable many-body correlations. Corresponding to this mapping, we develop an algorithm to efficiently sample a Slater-determinant wave function and compute all physical observables in dynamics with a polynomial cost in system size. The system shows information scrambling in the quantum many-body Hilbert space characterized by the spreading of Hamming distance. At late time we find emergence of classical diffusion dynamics in this quantum many-body system. We establish that the operator mapping enabled growth in an out-of-time-order correlator exhibits exponential-scrambling behavior. The quantum information-hiding mapping approach may shed light on the understanding of fundamental connections among computational complexity, information scrambling, and quantum thermalization.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.100.032309}, author = {Li, Xiaopeng and Zhu, Guanyu and Han, Muxin and Wang, Xin} } @article {ISI:000466809600017, title = {QUANTUM INFORMATION The US National Quantum Initiative: From Act to action}, journal = {Science}, volume = {364}, number = {6439}, year = {2019}, month = {MAY 3}, pages = {440-442}, publisher = {AMER ASSOC ADVANCEMENT SCIENCE}, type = {Editorial Material}, issn = {0036-8075}, doi = {10.1126/science.aax0578}, author = {Monroe, Christopher and Raymer, Michael G. and Taylor, Jacob} } @article { ISI:000496930000002, title = {Quantum Interference between Photons from an Atomic Ensemble and a Remote Atomic Ion}, journal = {Phys. Rev. Lett.}, volume = {123}, number = {21}, year = {2019}, month = {NOV 18}, pages = {213601}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Many remote-entanglement protocols rely on the generation and interference of photons produced by nodes within a quantum network. Quantum networks based on heterogeneous nodes provide a versatile platform by utilizing the complementary strengths of the differing systems. Implementation of such networks is challenging, due to the disparate spectral and temporal characteristics of the photons generated by the different quantum systems. Here, we report on the observation of quantum interference between photons generated from a single ion and an atomic ensemble. The photons are produced on demand by each source located in separate buildings, in a manner suitable for quantum networking. Given these results, we analyze the feasibility of hybrid ion-ensemble remote entanglement generation.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.213601}, author = {Craddock, A. N. and Hannegan, J. and Ornelas-Huerta, D. P. and Siverns, J. D. and Hachtel, A. J. and Goldschmidt, A. and Porto, J. V. and Quraishi, Q. and Rolston, S. L.} } @article { ISI:000498849400002, title = {Quantum many-body scars from magnon condensation}, journal = {Phys. Rev. B}, volume = {100}, number = {18}, year = {2019}, month = {NOV 27}, pages = {184312}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study the eigenstate properties of a nonintegrable spin chain that was recently realized experimentally in a Rydberg-atom quantum simulator. In the experiment, long-lived coherent many-body oscillations were observed only when the system was initialized in a particular product state. This pronounced coherence has been attributed to the presence of special {\textquoteleft}{\textquoteleft}scarred{{\textquoteright}{\textquoteright}} eigenstates with nearly equally spaced energies and putative nonergodic properties despite their finite energy density. In this paper we uncover a surprising connection between these scarred eigenstates and low-lying quasiparticle excitations of the spin chain. In particular, we show that these eigenstates can be accurately captured by a set of variational states containing a macroscopic number of magnons with momentum pi. This leads to an interpretation of the scarred eigenstates as finite-energy-density condensates of weakly interacting pi magnons. One natural consequence of this interpretation is that the scarred eigenstates possess long-range connected correlations in both space and time. We verify numerically the presence of this spatiotemporal long-range order and explain how it is consistent with established no-go theorems precluding its existence in ground states and at thermal equilibrium.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.184312}, author = {Iadecola, Thomas and Schecter, Michael and Xu, Shenglong} } @article {ISI:000476860700002, title = {Quantum repeaters based on two species trapped ions}, journal = {New J. Phys.}, volume = {21}, year = {2019}, month = {JUL 1}, pages = {073002}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {We examine the viability of quantum repeaters based on two-species trapped ion modules for long-distance quantum key distribution. Repeater nodes comprised of ion-trap modules of co-trapped ions of distinct species are considered. The species used for communication qubits has excellent optical properties while the other longer lived species serves as a memory qubit in the modules. Each module interacts with the network only via single photons emitted by the communication ions. Coherent Coulomb interaction between ions is utilized to transfer quantum information between the communication and memory ions and to achieve entanglement swapping between two memory ions. We describe simple modular quantum repeater architectures realizable with the ion-trap modules and numerically study the dependence of the quantum key distribution rate on various experimental parameters, including coupling efficiency, gate infidelity, operation time and length of the elementary links. Our analysis suggests crucial improvements necessary in a physical implementation for co-trapped two-species ions to be a competitive platform in long-distance quantum communication.}, keywords = {quantum key distribution, quantum repeaters, two species trapped ions}, issn = {1367-2630}, doi = {10.1088/1367-2630/ab2a45}, author = {Santra, Siddhartha and Muralidharan, Sreraman and Lichtman, Martin and Jiang, Liang and Monroe, Christopher and Malinovsky, Vladimir S.} } @article {ISI:000472681100001, title = {Quantum Sensing with Squeezed Light}, journal = {ACS Photonics}, volume = {6}, number = {6}, year = {2019}, month = {JUN}, pages = {1307-1318}, publisher = {AMER CHEMICAL SOC}, type = {Article}, abstract = {The minimum resolvable signal in sensing and metrology platforms that rely on optical readout fields is increasingly constrained by the standard quantum limit, which is determined by the sum of photon shot noise and back-action noise. A combination of back-action and shot noise reduction techniques will be critical to the development of the next generation of sensors for applications ranging from high-energy physics to biochemistry and for novel microscopy platforms capable of resolving material properties that were previously obscured by quantum noise. This Perspective reviews the dramatic advances made in the use of squeezed light for sub-shot-noise quantum sensing in recent years and highlights emerging applications that enable new science based on signals that would otherwise be obscured by noise at the standard quantum limit.}, keywords = {continuous variable quantum optics, quantum noise reduction, quantum sensing, squeezing}, issn = {2330-4022}, doi = {10.1021/acsphotonics.9b00250}, author = {Lawrie, B. J. and Lett, P. D. and Marino, A. M. and Pooser, R. C.} } @article {ISI:000482580900004, title = {Quantum work of an optical lattice}, journal = {Phys. Rev. B}, volume = {100}, number = {6}, year = {2019}, month = {AUG 26}, pages = {064308}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {A classic example of a quantum quench concerns the release of an interacting Bose gas from an optical lattice. The local properties of quenches such as this have been extensively studied; however, the global properties of these nonequilibrium quantum systems have received far less attention. Here we study several aspects of global nonequilibrium behavior by calculating the amount of work done by the quench as measured through the work distribution function. Using Bethe ansatz techniques, we determine the Loschmidt amplitude and work distribution function of the Lieb-Liniger gas after it is released from an optical lattice. We find the average work and its universal edge exponents from which we determine the long-time decay of the Loschmidt echo and highlight striking differences caused by the interactions as well as changes in the geometry of the system. We extend our calculation to the attractive regime of the model and show that the system exhibits properties similar to the super-Tonks-Girardeau gas. Finally, we examine the prominent role played by bound states in the work distribution and show that, with low probability, they allow for work to be extracted from the quench.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.064308}, author = {Rylands, Colin and Andrei, Natan} } @conference {ISI:000482226301355, title = {Quantum-correlated Light Source from Dual-seeded Four-wave Mixing with a Diode Laser System}, booktitle = {2019 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO)}, series = {Conference on Lasers and Electro-Optics}, year = {2019}, note = {Conference on Lasers and Electro-Optics (CLEO), San Jose, CA, MAY 05-10, 2019}, publisher = {IEEE; AdValue Photon; Amer Elements; Class5 Photon; Coherent; GoFoton; Light Convers; LightTrans; MKS; OZ Opt Online; Santec; ThorLabs; UQDevices; YSL Photon}, organization = {IEEE; AdValue Photon; Amer Elements; Class5 Photon; Coherent; GoFoton; Light Convers; LightTrans; MKS; OZ Opt Online; Santec; ThorLabs; UQDevices; YSL Photon}, type = {Proceedings Paper}, abstract = {We have obtained broadband intensity-difference squeezing from sub 10 Hz to 20 MHz via four-wave mixing (4WM) in a rubidium vapor. This was accomplished by dual-seeding the 4WM process and using semiconductor diode lasers. (C) 2019 The Author(s)}, isbn = {978-1-943580-57-6}, issn = {2160-9020}, author = {Wu, Meng-Chang and Brewer, Nicholas R. and Speirs, Rory W. and Schmittberger, Bonnie L. and Jones, Kevin M. and Lett, Paul D.} } @article {ISI:000470151800023, title = {Reduction of water-molecule-induced current-voltage hysteresis in graphene field effect transistor with semi-dry transfer using flexible supporter}, journal = {J. Appl. Phys.}, volume = {125}, number = {18}, year = {2019}, month = {MAY 14}, pages = {184302}, publisher = {AMER INST PHYSICS}, type = {Article}, abstract = {The polymethyl methacrylate-assisted wet transfer method of chemical vapor deposition (CVD) graphene has been widely used, thanks to its good coverage and simplicity. However, in the wet-transfer method, water molecules are inevitably trapped between the graphene and the substrate because the graphene is transferred to the substrate while floating in water. The trapped water molecules can cause the unwanted doping of graphene and hysteretic behavior in the current-voltage (I-V) curve. We here propose a new semidry transfer method using the Kapton tape as an additional flexible supporting layer. The N-2 blowing and heating processes are added to vaporize the water molecules adsorbed on graphene layer right before the transfer step. By comparing the I-V characteristics of wet-and semidry-transferred graphene field effect transistor (GFET), the field effect mobility is found to be larger for the semidry-transferred GFET in comparison with the wet-transferred one, possibly due to the more uniform Coulomb potential landscape. Most importantly, the hysteretic behavior is found to be reduced in accordance with the decrease of the trapped water molecules. The averaged electron mobilities obtained from the GFET measurements are 1118 cm(2)/Vs and 415 cm(2)/Vs for semidry- and wet-transferred graphene, respectively. Our semidry transfer method can provide a simple and reliable way to transfer the CVD graphene onto an arbitrary substrate with the minimized number of trapped water molecules, which is readily applicable for large-scale substrates with potential of commercialization.}, issn = {0021-8979}, doi = {10.1063/1.5089494}, author = {Jung, Sungchul and Yoon, Hoon Hahn and Jin, Hanbyul and Mo, Kyuhyung and Choi, Gahyun and Lee, Junghyun and Park, Hyesung and Park, Kibog} } @article { ISI:000503978100047, title = {Repeated measurements with minimally destructive partial-transfer absorption imaging}, journal = {Opt. Express}, volume = {27}, number = {25}, year = {2019}, month = {DEC 9}, pages = {36611-36624}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {We demonstrate partial-transfer absorption imaging as a technique for repeatedly imaging an ultracold atomic ensemble with minimal perturbation. We prepare an atomic cloud in a state that is dark to the imaging light. We then use a microwave pulse to coherently transfer a small fraction of the ensemble to a bright state, which we image using in situ absorption imaging. The amplitude or duration of the microwave pulse controls the fractional transfer from the dark to the bright state. For small transfer fractions, we can image the atomic cloud up to 50 times before it is depleted. As a sample application, we repeatedly image an atomic cloud oscillating in a dipole trap to measure the trap frequency. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {1094-4087}, doi = {10.1364/OE.27.036611}, author = {Seroka, Erin Marshall and Curiel, Ana Valdes and Trypogeorgos, Dimitrios and Lundblad, Nathan and Spielman, Ian B.} } @article { ISI:000500743400001, title = {Rydberg-Mediated Entanglement in a Two-Dimensional Neutral Atom Qubit Array}, journal = {Phys. Rev. Lett.}, volume = {123}, number = {23}, year = {2019}, month = {DEC 4}, pages = {230501}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We demonstrate high fidelity two-qubit Rydberg blockade and entanglement on a pair of sites in a large two-dimensional qubit array. The qubit array is defined by a grid of blue detuned lines of light with 121 sites for trapping atomic qubits. Improved experimental methods have increased the observed Bell state fidelity to F-Bell = 0.86(2). Accounting for errors in state preparation and measurement we infer a fidelity of F-(SPAM)(Bell) = 0.88. Accounting for errors in single qubit operations we infer that a Bell state created with the Rydberg mediated C-Z gate has a fidelity of F-Bell(CZ) = 0.89. Comparison with a detailed error model based on quantum process matrices indicates that finite atom temperature and laser noise are the dominant error sources contributing to the observed gate infidelity.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.230501}, author = {Graham, T. M. and Kwon, M. and Grinkemeyer, B. and Marra, Z. and Jiang, X. and Lichtman, M. T. and Sun, Y. and Ebert, M. and Saffman, M.} } @article {ISI:000482547000001, title = {Sauter-Schwinger effect with a quantum gas}, journal = {New J. Phys.}, volume = {21}, year = {2019}, month = {AUG 21}, pages = {083035}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {The creation of particle-antiparticle pairs from vacuum by a large electric field is at the core of quantum electrodynamics. Despite the wide acceptance that this phenomenon occurs naturally when electric field strengths exceed E-c approximate to 10(18) Vm(-1), it has yet to be experimentally observed due to the limitations imposed by producing electric fields at this scale. The high degree of experimental control present in ultracold atomic systems allow experimentalists to create laboratory analogs to high-field phenomena. Here we emulated massive relativistic particles subject to large electric field strengths, thereby quantum-simulated particle-antiparticle pair creation, and experimentally explored particle creation from {\textquoteleft}the Dirac vacuum{\textquoteright}. Data collected from our analog system spans the full parameter regime from low applied field (negligible pair creation) below the Sauter-Schwinger limit, to high field (maximum rate of pair creation) far in excess of the Sauter-Schwinger limit. In our experiment, we perform direct measurements on an analog atomic system and show that this high-field phenomenon is well-characterized by Landau-Zener tunneling, well known in the atomic physics context, and we find full quantitative agreement with theory with no adjustable parameters.}, keywords = {particle creation, quantum gases, quantum simulation, Sauter-Schwinger effect}, issn = {1367-2630}, doi = {10.1088/1367-2630/ab3840}, author = {Pineiro, A. M. and Genkina, D. and Lu, Mingwu and Spielman, I. B.} } @article {ISI:000462935500003, title = {Scale-Invariant Continuous Entanglement Renormalization of a Chern Insulator}, journal = {Phys. Rev. Lett.}, volume = {122}, number = {12}, year = {2019}, month = {MAR 27}, pages = {120502}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The multiscale entanglement renormalization ansatz (MERA) postulates the existence of quantum circuits that renormalize entanglement in real space at different length scales. Chem insulators, however, cannot have scale-invariant discrete MERA circuits with a finite bond dimension. In this Letter, we show that the continuous MERA (cMERA), a modified version of MERA adapted for field theories, possesses a fixed point wave function with a nonzero Chern number. Additionally, it is well known that reversed MERA circuits can be used to prepare quantum states efficiently in time that scales logarithmically with the size of the system. However, state preparation via MERA typically requires the advent of a full-fledged universal quantum computer. In this Letter, we demonstrate that our cMERA circuit can potentially be realized in existing analog quantum computers, i.e., an ultracold atomic Fermi gas in an optical lattice with light-induced spin-orbit coupling.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.122.120502}, author = {Chu, Su-Kuan and Zhu, Guanyu and Garrison, James R. and Eldredge, Zachary and Curiel, Ana Valdes and Bienias, Przemyslaw and Spielman, I. B. and Gorshkov, V, Alexey} } @article { ISI:000501541900004, title = {Scanning tunneling Andreev microscopy of titanium nitride thin films}, journal = {Phys. Rev. B}, volume = {100}, number = {21}, year = {2019}, month = {DEC 9}, pages = {214505}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We report scanning tunneling microscopy results on 25- and 50-nm-thick films of superconducting TiN that show Andreev tunneling behavior at 0.5 K. At most locations on the topographically rough surfaces, we observe tip-sample current-voltage characteristics with a clear superconducting gap, as expected for superconductor-normal (S-N) tunneling through a low-transparency barrier, while in some places, we find a zero-voltage conductance peak, as expected for S-N Andreev tunneling through a highly transparent barrier. Fitting the Blonder-Tinkham-Klapwijk model to the conductance data allows an accurate extraction of the TiN superconducting gap Delta, by accounting for local variations in the tip-sample barrier height Z and junction temperature T. From spatial maps of the model parameters, we find that both films show a strong inhomogeneity, with Delta varying by as much as a factor of 2 from grain to grain. In the thicker film, however, correlations between T, Z, and Delta suggest the grains are thermally isolated, perhaps due to internal stress. We discuss possible mechanisms that could produce these large correlated variations, including local heating and surface contamination, and consider some of the implications for devices made from such films.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.214505}, author = {Liao, Wan-Ting and Kohler, T. P. and Osborn, K. D. and Butera, R. E. and Lobb, C. J. and Wellstood, F. C. and Dreyer, M.} } @article {ISI:000462882400010, title = {Scrambling in the Dicke model}, journal = {Phys. Rev. A}, volume = {99}, number = {4}, year = {2019}, month = {APR 1}, pages = {043602}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The scrambling rate lambda(L) associated with the exponential growth of out-of-time-ordered correlators can be used to characterize quantum chaos. Here we use a particular Majorana fermion representation of spin-1/2 systems to study quantum chaos in the Dicke model. We take the system to be in thermal equilibrium and compute lambda(L) throughout the phase diagram to leading order in 1/N. We find that the chaotic behavior is strongest close to the critical point. At high temperatures lambda(L) is nonzero over an extended region that includes both the normal and superradiant phases. At low temperatures lambda(L) is nonzero in (a) close vicinity of the critical point and (b) a region within the superradiant phase. In the process we also derive an effective theory for the superradiant phase at finite temperatures Our formalism does not rely on the assumption of total spin conservation.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.99.043602}, author = {Alavirad, Yahya and Lavasani, Ali} } @article {ISI:000471993700016, title = {The Search for Variation of Fundamental Constants with Clocks}, journal = {Ann. Phys.-Berlin}, volume = {531}, number = {5, SI}, year = {2019}, month = {MAY}, pages = {1800364}, publisher = {WILEY-V C H VERLAG GMBH}, type = {Article}, abstract = {In many theories beyond the Standard Model the quantities that we call {\textquoteleft}{\textquoteleft}fundamental constants{{\textquoteright}{\textquoteright}} become space-time dependent, leading to corresponding variation of atomic and molecular spectra and clock frequencies. The extraordinary improvement of the atomic clock precision in the past fifteen years enabled testing the constancy of the fundamental constant at a very high level of precision. Herein, searches for the variation of fundamental constants with clocks are discussed, focusing on recent key results and future proposals, including highly charged ion, molecular, and nuclear clocks. The relevance of the recent searches for oscillatory and transient variation of fundamental constants to the major unexplained phenomena of our Universe, the nature of dark matter, is discussed.}, keywords = {atomic clocks, highly charged ions, nuclear clock, variation of fundamental constants}, issn = {0003-3804}, doi = {10.1002/andp.201800364}, author = {Safronova, Marianna S.} } @article {ISI:000482530000002, title = {A semiclassical theory of phase-space dynamics of interacting bosons}, journal = {J. Phys. B-At. Mol. Opt. Phys.}, volume = {52}, number = {18}, year = {2019}, month = {SEP 28}, pages = {185302}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {We study the phase-space representation of dynamics of bosons in the semiclassical regime where the occupation number of the modes is large. To this end, we employ the van Vleck-Gutzwiller propagator to obtain an approximation for the Green{\textquoteright}s function of the Wigner distribution. The semiclassical analysis incorporates interference of classical paths and reduces to the truncated Wigner approximation (TWA) when the interference is ignored. Furthermore, we identify the Ehrenfest time after which the TWA fails. As a case study, we consider a single-mode quantum nonlinear oscillator, which displays collapse and revival of observables. We analytically show that the interference of classical paths leads to revivals, an effect that is not reproduced by the TWA or a perturbative analysis.}, keywords = {Bose-Einstein condensates, phase-space dynamics, semiclassical physics}, issn = {0953-4075}, doi = {10.1088/1361-6455/ab319c}, author = {Mathew, R. and Tiesinga, E.} } @article {ISI:000470849000068, title = {Silicon photonic add-drop filter for quantum emitters}, journal = {Opt. Express}, volume = {27}, number = {12}, year = {2019}, month = {JUN 10}, pages = {16882-16889}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {Integration of single-photon sources and detectors to silicon-based photonics opens the possibility of complex circuits for quantum information processing. In this work. we demonstrate integration of quantum dots with a silicon photonic add-drop filter for on-chip filtering and muting of telecom photons. A silicon microdisk resonator acts as a narrow filter that transfers the quantum dot emission and filters the background over a wide wavelength range. Moreover, by tuning the quantum dot emission wavelength over the resonance of the microdisk, we can control the transmission of the quantum dot emission to the drop and through channels of the add-drop filter. This result is a step toward the on-chip control of single photons using silicon photonics for applications in quantum information processing. such as linear optical quantum computation and boson sampling. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {1094-4087}, doi = {10.1364/OE.27.016882}, author = {Aghaeimeibodi, Shahriar and Kim, Je-Hyung and Lee, Chang-Min and Buyukkaya, Mustafa Atabey and Richardson, Christopher and Waks, Edo} } @article {ISI:000478993000006, title = {Simulation of the coupling strength of capacitively coupled singlet-triplet qubits}, journal = {Phys. Rev. B}, volume = {100}, number = {7}, year = {2019}, month = {AUG 6}, pages = {075411}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We consider a system of two purely capacitively coupled singlet-triplet qubits and numerically simulate the energy structure of four electrons in two double quantum dots with a large potential barrier between them. We calculate the interqubit coupling strength using an extended Hund-Mulliken approach which includes excited orbitals in addition to the lowest-energy orbital for each quantum dot. We show the coupling strength as a function of the qubit separation as well as plotting it against the detunings of the two double quantum dots and show that the general qualitative features of our results can be captured by a potential-independent toy model of the system.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.075411}, author = {Buterakos, Donovan and Throckmorton, Robert E. and S. Das Sarma} } @article { ISI:000490353500045, title = {A Spin-Photon Interface Using Charge-Tunable Quantum Dots Strongly Coupled to a Cavity}, journal = {Nano Lett.}, volume = {19}, number = {10}, year = {2019}, month = {OCT}, pages = {7072-7077}, publisher = {AMER CHEMICAL SOC}, type = {Article}, abstract = {Charged quantum dots containing an electron or hole spin are bright solid-state qubits suitable for quantum networks and distributed quantum computing. Incorporating such quantum dot spin into a photonic crystal cavity creates a strong spin-photon interface in which the spin can control a photon by modulating the cavity reflection coefficient. However, previous demonstrations of such spin-photon interfaces have relied on quantum dots that are charged randomly by nearby impurities, leading to instability in the charge state, which causes poor contrast in the cavity reflectivity. Here we demonstrate a strong spin-photon interface using a quantum dot that is charged deterministically with a diode structure. By incorporating this actively charged quantum dot in a photonic crystal cavity, we achieve strong coupling between the cavity mode and the negatively charged state of the dot. Furthermore, by initializing the spin through optical pumping, we show strong spin-dependent modulation of the cavity reflectivity, corresponding to a cooperativity of 12. This spin-dependent reflectivity is important for mediating entanglement between spins using photons, as well as generating strong photon-photon interactions for applications in quantum networking and distributed quantum computing.}, keywords = {cavity quantum electrodynamics, Quantum Dots, single electron spin, strong light-matter interaction}, issn = {1530-6984}, doi = {10.1021/acs.nanolett.9b02443}, author = {Luo, Zhouchen and Sun, Shuo and Karasahin, Aziz and Bracker, Allan S. and Carter, Samuel G. and Yakes, Michael K. and Gammon, Daniel and Waks, Edo} } @article { ISI:000492332900005, title = {Stroboscopic approach to trapped-ion quantum information processing with squeezed phonons}, journal = {Phys. Rev. A}, volume = {100}, number = {4}, year = {2019}, month = {OCT 24}, pages = {043417}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {In trapped-ion quantum information processing, interactions between spins (qubits) are mediated by collective modes of motion of an ion crystal. While there are many different experimental strategies to design such interactions, they all face both technical and fundamental limitations to the achievable coherent interaction strength. In general, obtaining strong interactions and fast gates is an ongoing challenge. Here, we extend previous work {[}W. Ge, B. C. Sawyer, J. W. Britton, K. Jacobs, J. J. Bollinger, and M. Foss-Feig, Phys. Rev. Lett. 122, 030501 (2019)] and present a general strategy for enhancing the interaction strengths in trapped-ion systems via parametric amplification of the ions{\textquoteright} motion. Specifically, we propose a stroboscopic protocol using alternating applications of parametric amplification and spin-motion coupling. In comparison with the previous work, we show that the current protocol can lead to larger enhancements in the coherent interaction that increase exponentially with the gate time.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.100.043417}, author = {Ge, Wenchao and Sawyer, Brian C. and Britton, Joseph W. and Jacobs, Kurt and Foss-Feig, Michael and Bollinger, John J.} } @conference {ISI:000466478500026, title = {Structured neutron waves}, booktitle = {OPTICAL, OPTO-ATOMIC, AND ENTANGLEMENT-ENHANCED PRECISION METROLOGY}, series = {Proceedings of SPIE}, volume = {10934}, year = {2019}, note = {Conference on Optical, Opto-Atomic, and Entanglement-Enhanced Precision Metrology, San Francisco, CA, FEB 02-07, 2019}, pages = {1093425}, publisher = {SPIE}, organization = {SPIE}, type = {Proceedings Paper}, abstract = {Emerging quantum materials are becoming the building blocks for quantum devices and they are enabling new advances from spintronics to topological insulators. Their functionality typically comes from their inner magnetic field structure. Neutrons are a particularly good probe to characterize such features. The control of neutron orbital angular momentum and the spin-orbit interaction enables new characterizing techniques and increased sensitivity towards specific material properties. Here we review the preparation and characterization methods of structured neutron waves.}, keywords = {Neutron Interferometry, Neutrons, orbital angular momentum, spin-orbit states, Structured Waves}, isbn = {978-1-5106-2511-2}, issn = {0277-786X}, doi = {10.1117/12.2515469}, author = {Sarenac, Dusan and Clark, Charles W. and Cory, David G. and Kapahi, Connor and Heacock, Benjamin and Huber, Michael G. and Nsofini, Joachim and Shahi, Chandra B. and Pushin, Dmitry A.}, editor = {Shahriar, SM and Scheuer, J} } @article {ISI:000485761800002, title = {Superconductor versus insulator in twisted bilayer graphene}, journal = {Phys. Rev. B}, volume = {100}, number = {11}, year = {2019}, month = {SEP 13}, pages = {115128}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We present a simple model that we believe captures the key aspects of the competition between superconducting and insulating states in twisted bilayer graphene. Within this model, the superconducting phase is primary, and arises at generic fillings, but is interrupted by the insulator at commensurate fillings. Importantly, the insulator forms because of electron-electron interactions, but the model is agnostic as to the superconducting pairing mechanism, which need not originate with electron-electron interactions. The model is composed of a collection of crossed one-dimensional quantum wires whose intersections form a superlattice. At each superlattice point, we place a locally superconducting puddle which can exchange Cooper pairs with the quantum wires. We analyze this model assuming weak wire-puddle and wire-wire couplings. We show that for a range of repulsive intrawire interactions, the system is superconducting at {\textquoteleft}{\textquoteleft}generic{{\textquoteright}{\textquoteright}} incommensurate fillings, with the superconductivity being {\textquoteleft}{\textquoteleft}interrupted{{\textquoteright}{\textquoteright}} by an insulating phase at commensurate fillings. We further show that the gapped insulating states at commensurate fillings give way to gapless states upon application of external Zeeman fields. These features are consistent with experimental observations in magic-angle twisted bilayer graphenes despite the distinct microscopic details. We further study the full phase diagram of this model and discover that it contains several distinct correlated insulating states, which we characterize herein.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.115128}, author = {Chou, Yang-Zhi and Lin, Yu-Ping and S. Das Sarma and Nandkishore, Rahul M.} } @article { ISI:000492968000008, title = {Supercurrent interference in semiconductor nanowire Josephson junctions}, journal = {Phys. Rev. B}, volume = {100}, number = {15}, year = {2019}, month = {OCT 28}, pages = {155431}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Semiconductor-superconductor hybrid systems provide a promising platform for hosting unpaired Majorana fermions towards the realization of fault-tolerant topological quantum computing. In this study we employ the Keldysh nonequilibrium Green{\textquoteright}s function formalism to model quantum transport in normal-superconductor junctions. We analyze III-V semiconductor nanowire Josephson junctions (InAs/Nb) using a three-dimensional discrete lattice model described by the Bogoliubov-de Gennes Hamiltonian in the tight-binding approximation, and compute the Andreev bound state spectrum and current-phase relations. Recent experiments {[}Zuo et al., Phys. Rev. Lett. 119, 187704 (2017) and Gharavi et al., arXiv: 1405.7455] reveal critical current oscillations in these devices, and our simulations confirm these to be an interference effect of the transverse subbands in the nanowire. We add disorder to model coherent scattering and study its effect on the critical current oscillations, with an aim to gain a thorough understanding of the experiments. The oscillations in the disordered junction are highly sensitive to the particular realization of the random disorder potential, and to the gate voltage. A macroscopic current measurement thus gives us information about the microscopic profile of the junction. Finally, we study dephasing in the channel by including elastic phase-breaking interactions. The oscillations thus obtained are in good qualitative agreement with the experimental data, and this signifies the essential role of phase-breaking processes in III-V semiconductor nanowire Josephson junctions.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.155431}, author = {Sriram, Praveen and Kalantre, Sandesh S. and Gharavi, Kaveh and Baugh, Jonathan and Muralidharan, Bhaskaran} } @article { ISI:000459821800002, title = {Superstrong coupling in circuit quantum electrodynamics}, journal = {NPJ QUANTUM INFORMATION}, volume = {5}, year = {2019}, month = {FEB 25}, pages = {20}, issn = {2056-6387}, doi = {10.1038/s41534-019-0134-2}, author = {Kuzmin, Roman and Mehta, Nitish and Grabon, Nicholas and Mencia, Raymond and Manucharyan, Vladimir E.} } @article {ISI:000479034100005, title = {Suppressing Inhomogeneous Broadening in a Lutetium Multi-ion Optical Clock}, journal = {Phys. Rev. Lett.}, volume = {123}, number = {6}, year = {2019}, month = {AUG 7}, pages = {063201}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We demonstrate precision measurement and control of inhomogeneous broadening in a multi-ion clock consisting of three Lu-176(+) ions. Microwave spectroscopy between hyperfine states in the D-3(1) level is used to characterize differential systematic shifts between ions, most notably those associated with the electric quadrupole moment. By appropriate alignment of the magnetic field, we demonstrate suppression of these effects to the similar to 10(-17) level relative to the S-1(0) <-> D-3(1) optical transition frequency. Correlation spectroscopy on the optical transition demonstrates the feasibility of a 10-s Ramsey interrogation in the three ion configuration with a corresponding projection noise limited stability of sigma(tau) = 8.2 x 10(-17)/root tau.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.063201}, author = {Tan, T. R. and Kaewuam, R. and Arnold, K. J. and Chanu, S. R. and Zhang, Zhiqiang and Safronova, M. S. and Barrett, M. D.} } @article {ISI:000461940700022, title = {Switchable detector array scheme to reduce the effect of single-photon detector{\textquoteright}s deadtime in a multi-bit/photon quantum link}, journal = {Opt. Commun.}, volume = {441}, year = {2019}, month = {JUN 15}, pages = {132-137}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, abstract = {{We explore the use of a switchable single-photon detector (SPD) array scheme to reduce the effect of a detector{\textquoteright}s deadtime for a multi-bit/photon quantum link. The case of data encoding using M possible orbital-angular-momentum (OAM) states is specifically studied in this paper. Our method uses N SPDs with a controllable M x N optical switch and we use a Monte Carlo-based method to simulate the quantum detection process. The simulation results show that with the use of the switchable SPD array, the detection system can allow a higher incident photon rate than what might otherwise be limited by detectors{\textquoteright} deadtime. For the case of M = 4}, keywords = {orbital angular momentum, quantum communication, Single photon detection}, issn = {0030-4018}, doi = {10.1016/j.optcom.2019.01.081}, author = {Liu, Cong and Ren, Yongxiong and Zhao, Jiapeng and Mirhosseini, Mohammad and Rafsanjani, Seyed Mohammad Hashemi and Xie, Guodong and Pang, Kai and Song, Haoqian and Zhao, Zhe and Wang, Zhe and Li, Long and Bienfang, Joshua C. and Migdall, Alan and Brun, Todd A. and Tur, Moshe and Boyd, Robert W. and Willner, Alan E.} } @article { ISI:000489831000001, title = {Synthetic Gauge Field for Two-Dimensional Time-Multiplexed Quantum Random Walks}, journal = {Phys. Rev. Lett.}, volume = {123}, number = {15}, year = {2019}, month = {OCT 11}, pages = {150503}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Temporal multiplexing provides an efficient and scalable approach to realize a quantum random walk with photons that can exhibit topological properties. But two-dimensional time-multiplexed topological quantum walks studied so far have relied on generalizations of the Su-Shreiffer-Heeger model with no synthetic gauge field. In this work, we demonstrate a two-dimensional topological quantum random walk where the nontrivial topology is due to the presence of a synthetic gauge field. We show that the synthetic gauge field leads to the appearance of multiple band gaps and, consequently, a spatial confinement of the quantum walk distribution. Moreover, we demonstrate topological edge states at an interface between domains with opposite synthetic fields. Our results expand the range of Hamiltonians that can be simulated using photonic quantum walks.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.150503}, author = {Chalabi, Hamidreza and Barik, Sabyasachi and Mittal, Sunil and Murphy, Thomas E. and Hafezi, Mohammad and Waks, Edo} } @article {ISI:000455826000001, title = {Tabletop experiments for quantum gravity: a user{\textquoteright}s manual}, journal = {Class. Quantum Gravity}, volume = {36}, number = {3}, year = {2019}, month = {FEB 7}, pages = {034001}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {Recent advances in cooling, control, and measurement of mechanical systems in the quantum regime have opened the possibility of the first direct observation of quantum gravity, at scales achievable in experiments. This paper gives a broad overview of this idea, using some matter-wave and optomechanical systems to illustrate the predictions of a variety of models of low-energy quantum gravity. We first review the treatment of perturbatively quantized general relativity as an effective quantum field theory, and consider the particular challenges of observing quantum effects in this framework. We then move on to a variety of alternative models, such as those in which gravity is classical, emergent, or responsible for a breakdown of quantum mechanics.}, keywords = {experimental tests, Optomechanics, quantum gravity}, issn = {0264-9381}, doi = {10.1088/1361-6382/aaf9ca}, author = {Carney, Daniel and Stamp, Philip C. E. and Taylor, Jacob M.} } @article {14281, title = {Theory of Bose condensation of light via laser cooling of atoms}, journal = {Phys. Rev. A}, volume = {99}, year = {2019}, month = {Mar}, pages = {031801}, author = {Wang, Chiao-Hsuan and Gullans, M. J. and Porto, J. V. and Phillips, William D. and Taylor, Jacob M.} } @article {ISI:000461896700001, title = {Theory of Bose condensation of light via laser cooling of atoms}, journal = {Phys. Rev. A}, volume = {99}, number = {3}, year = {2019}, month = {MAR 14}, pages = {031801}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {A Bose-Einstein condensate (BEC) is a quantum phase of matter achieved at low temperatures. Photons, one of the most prominent species of bosons, do not typically condense due to the lack of a particle number conservation. We recently described a photon thermalization mechanism which gives rise to a grand canonical ensemble of light with effective photon number conservation between a subsystem and a particle reservoir. This mechanism occurs during Doppler laser cooling of atoms where the atoms serve as a temperature reservoir while the cooling laser photons serve as a particle reservoir. In contrast to typical discussions of BEC, our system is better treated with a controlled chemical potential rather than a controlled particle number, and is subject to energy-dependent loss. Here, we address the question of the possibility of a BEC of photons in this laser cooling photon thermalization scenario and theoretically demonstrate that a Bose condensation of photons can be realized by cooling an ensemble of two-level atoms (realizable with alkaline-earth atoms) inside a Fabry-Perot cavity.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.99.031801}, author = {Wang, Chiao-Hsuan and Gullans, M. J. and Porto, V, J. and Phillips, William D. and Taylor, Jacob M.} } @article {ISI:000473009200001, title = {Theory of coherent phase modes in insulating Josephson junction chains}, journal = {Phys. Rev. B}, volume = {99}, number = {21}, year = {2019}, month = {JUN 21}, pages = {214509}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Recent microwave reflection measurements of Josephson junction chains have suggested the presence of nearly coherent collective charge oscillations deep in the insulating phase. Here we develop a qualitative understanding of such coherent charge modes by studying the local dynamical polarizability of the insulating phase of a finite length sine-Gordon model. By considering parameters near the noninteracting fermion limit where the charge operator dominantly couples to soliton-antisoliton pairs of the sine-Gordon model, we find that the local dynamical polarizability shows an array of sharp peaks in frequency representing coherent phase oscillations on top of an incoherent background. The strength of the coherent peaks relative to the incoherent background increases as a power law in frequency as well as exponentially as the Luttinger parameter approaches a critical value. The dynamical polarizability also clearly shows the insulating gap. We then compare the results in the high frequency limit to a perturbative estimate of phase-slip-induced decay of plasmons in the Josephson junction chain.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.214509}, author = {Wu, Huan-Kuang and Sau, Jay D.} } @article {ISI:000471983100001, title = {Thermal radiation as a probe of one-dimensional electron liquids}, journal = {Phys. Rev. B}, volume = {99}, number = {23}, year = {2019}, month = {JUN 11}, pages = {235124}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Motivated by recent developments in the field of plasmonics, we develop the theory of radiation from one-dimensional electron liquids, showing that the spectrum of thermal radiation emitted from the system exhibits signatures of non-Fermi liquid behavior. We derive a multipole expansion for the radiation based on the Tomonaga-Luttinger liquid model. While the dipole radiation pattern is determined by the conductivity of the system, we demonstrate that the quadrupole radiation can reveal important features of the quantum liquid, such as the Luttinger parameter. Radiation offers a probe of the interactions of the system, including Mott physics as well as nonlinear Luttinger liquid behavior. We show that these effects can be probed in current experiments on effectively one-dimensional electron liquids, such as carbon nanotubes.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.235124}, author = {DeGottardi, Wade and Gullans, Michael J. and Hegde, Suraj and Vishveshwara, Smitha and Hafezi, Mohammad} } @article {ISI:000464711300007, title = {Tools for designing atom interferometers in a microgravity environment}, journal = {Phys. Rev. A}, volume = {99}, number = {4}, year = {2019}, month = {APR 15}, pages = {043615}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We present a variational model suitable for rapid preliminary design of atom interferometers in a microgravity environment. The model approximates the solution of the three-dimensional rotating-frame Gross-Pitaevskii equation as the sum of N-c Gaussian clouds. Each Gaussian cloud is assumed to have time-dependent center positions, widths, and linear and quadratic phase parameters. We applied the Lagrangian variational method (LVM) with this trial wave function to derive equations of motion for these parameters that can be adapted to any external potential. We also present a one-dimensional (1D) version of this variational model. As an example we apply the model to a 1D atom interferometry scheme for measuring Newton{\textquoteright}s gravitational constant, G, in a microgravity environment. We show how the LVM model can (1) constrain the experimental parameter space size, (2) show how the value of G can be obtained from the experimental conditions and interference pattern characteristics, and (3) show how to improve the sensitivity of the measurement and construct a preliminary error budget.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.99.043615}, author = {Ashwood, Elizabeth and Wells, Ed Wesley and Kurkcuoglu, Doga Murat and Sapp, Robert Colson and Clark, Charles W. and Edwards, Mark} } @article {ISI:000462967000001, title = {Topological bands for ultracold atoms}, journal = {Rev. Mod. Phys.}, volume = {91}, number = {1}, year = {2019}, month = {MAR 25}, pages = {015005}, publisher = {AMER PHYSICAL SOC}, type = {Review}, abstract = {There have been significant recent advances in realizing band structures with geometrical and topological features in experiments on cold atomic gases. This review summarizes these developments, beginning with a summary of the key concepts of geometry and topology for Bloch bands. Descriptions are given of the different methods that have been used to generate these novel band structures for cold atoms and of the physical observables that have allowed their characterization. The focus is on the physical principles that underlie the different experimental approaches, providing a conceptual framework within which to view these developments. Also described is how specific experimental implementations can influence physical properties. Moving beyond single-particle effects, descriptions are given of the forms of interparticle interactions that emerge when atoms are subjected to these energy bands and of some of the many-body phases that may be sought in future experiments.}, issn = {0034-6861}, doi = {10.1103/RevModPhys.91.015005}, author = {Cooper, N. R. and Dalibard, J. and Spielman, I. B.} } @article {ISI:000467383900001, title = {Topological chiral superconductivity with spontaneous vortices and supercurrent in twisted bilayer graphene}, journal = {Phys. Rev. B}, volume = {99}, number = {19}, year = {2019}, month = {MAY 8}, pages = {195114}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study d-wave superconductivity in twisted bilayer graphene and reveal phenomena that arise due to the moire superlattice. In the d-wave pairing, the relative motion (RM) of two electrons in a Cooper pair can have either d + id or d - id symmetry with opposite angular momenta. Due to the enlarged moire superlattice, the center-of-mass motion (COMM) can also carry a finite angular momentum while preserving the moire periodicity. By matching the total angular momentum, which has contributions from both the RM and the COMM, Cooper pairs with d + id and d - id RMs are intrinsically coupled in a way such that the COMM associated with one of the RMs has a spontaneous vortex-antivortex lattice configuration. Another phenomenon is that the chiral d-wave state carries spontaneous bulk circulating supercurrent. The chiral d-wave superconductors are gapped and also topological as characterized by an integer Chern number. Nematic d-wave superconductors, which could be stabilized, for example, by uniaxial strain, are gapless with point nodes.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.195114}, author = {Wu, Fengcheng} } @article {ISI:000459920900007, title = {Topological Insulators in Twisted Transition Metal Dichalcogenide Homobilayers}, journal = {Phys. Rev. Lett.}, volume = {122}, number = {8}, year = {2019}, month = {FEB 28}, pages = {086402}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We show that moire bands of twisted homobilayers can be topologically nontrivial, and illustrate the tendency by studying valence band states in +/- K valleys of twisted bilayer transition metal dichalcogenides, in particular, bilayer MoTe2. Because of the large spin-orbit splitting at the monolayer valence band maxima, the low energy valence states of the twisted bilayer MoTe2 at the +K (-K) valley can be described using a two-band model with a layer-pseudospin magnetic field Delta(r) that has the moire period. We show that Delta(r) has a topologically nontrivial skyrmion lattice texture in real space, and that the topmost moire valence bands provide a realization of the Kane-Mele quantum spin-Hall model, i. e., the two-dimensional time-reversal-invariant topological insulator. Because the bands narrow at small twist angles, a rich set of broken symmetry insulating states can occur at integer numbers of electrons per moire cell.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.122.086402}, author = {Wu, Fengcheng and Lovorn, Timothy and Tutuc, Emanuel and Martin, Ivar and MacDonald, A. H.} } @article {ISI:000474394600005, title = {Topological nanomaterials}, journal = {Nat. Rev. Mater.}, volume = {4}, number = {7}, year = {2019}, month = {JUL}, pages = {479-496}, publisher = {NATURE PUBLISHING GROUP}, type = {Review}, abstract = {The past decade has witnessed the emergence of a new frontier in condensed matter physics: topological materials with an electronic band structure belonging to a different topological class from that of ordinary insulators and metals. This non-trivial band topology gives rise to robust, spin-polarized electronic states with linear energy-momentum dispersion at the edge or surface of the materials. For topological materials to be useful in electronic devices, precise control and accurate detection of the topological states must be achieved in nanostructures, which can enhance the topological states because of their large surface-to-volume ratios. In this Review, we discuss notable synthesis and electron transport results of topological nanomaterials, from topological insulator nanoribbons and plates to topological crystalline insulator nanowires and Weyl and Dirac semimetal nanobelts. We also survey superconductivity in topological nanowires, a nanostructure platform that might enable the controlled creation of Majorana bound states for robust quantum computations. Two material systems that can host Majorana bound states are compared: spin-orbit coupled semiconducting nanowires and topological insulating nanowires, a focus of this Review. Finally, we consider the materials and measurement challenges that must be overcome before topological nanomaterials can be used in next-generation electronic devices.

}, issn = {2058-8437}, doi = {10.1038/s41578-019-0113-4}, author = {Liu, Pengzi and James R. Williams and Cha, Judy J.} } @article {ISI:000462967000002, title = {Topological photonics}, journal = {Rev. Mod. Phys.}, volume = {91}, number = {1}, year = {2019}, month = {MAR 25}, pages = {015006}, publisher = {AMER PHYSICAL SOC}, type = {Review}, abstract = {Topological photonics is a rapidly emerging field of research in which geometrical and topological ideas are exploited to design and control the behavior of light. Drawing inspiration from the discovery of the quantum Hall effects and topological insulators in condensed matter, recent advances have shown how to engineer analogous effects also for photons, leading to remarkable phenomena such as the robust unidirectional propagation of light, which hold great promise for applications. Thanks to the flexibility and diversity of photonics systems, this field is also opening up new opportunities to realize exotic topological models and to probe and exploit topological effects in new ways. This article reviews experimental and theoretical developments in topological photonics across a wide range of experimental platforms, including photonic crystals, waveguides, metamaterials, cavities, optomechanics, silicon photonics, and circuit QED. A discussion of how changing the dimensionality and symmetries of photonics systems has allowed for the realization of different topological phases is offered, and progress in understanding the interplay of topology with non-Hermitian effects, such as dissipation, is reviewed. As an exciting perspective, topological photonics can be combined with optical nonlinearities, leading toward new collective phenomena and novel strongly correlated states of light, such as an analog of the fractional quantum Hall effect.}, issn = {0034-6861}, doi = {10.1103/RevModPhys.91.015006}, author = {Ozawa, Tomoki and Price, Hannah M. and Amo, Alberto and Goldman, Nathan and Hafezi, Mohammad and Lu, Ling and Rechtsman, Mikael C. and Schuster, David and Simon, Jonathan and Zilberberg, Oded and Carusotto, Iacopo} } @article { ISI:000502778700003, title = {Toward convergence of effective-field-theory simulations on digital quantum computers}, journal = {Phys. Rev. A}, volume = {100}, number = {6}, year = {2019}, month = {DEC 16}, pages = {062319}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We report results for simulating an effective field theory to compute the binding energy of the deuteron nucleus using a hybrid algorithm on a trapped-ion quantum computer. Two increasingly complex unitary coupled-cluster ansatze have been used to compute the binding energy to within a few percent for successively more complex Hamiltonians. By increasing the complexity of the Hamiltonian, allowing more terms in the effective field theory expansion, and calculating their expectation values, we present a benchmark for quantum computers based on their ability to scalably calculate the effective field theory with increasing accuracy. Our result of E-4 = - 2.220 +/- 0.179 MeV may be compared with the exact deuteron ground-state energy -2.224 MeV. We also demonstrate an error mitigation technique using Richardson extrapolation on ion traps. The error mitigation circuit represents a record for deepest quantum circuit on a trapped-ion quantum computer.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.100.062319}, author = {Shehab, O. and Landsman, K. and Nam, Y. and Zhu, D. and Linke, N. M. and Keesan, M. and Pooser, R. C. and Monroe, C.} } @conference {ISI:000482226302343, title = {Toward experimental implementation of quantum-enabled, bandwidth and power efficient communications}, booktitle = {2019 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO)}, series = {Conference on Lasers and Electro-Optics}, year = {2019}, note = {Conference on Lasers and Electro-Optics (CLEO), San Jose, CA, MAY 05-10, 2019}, publisher = {IEEE; AdValue Photon; Amer Elements; Class5 Photon; Coherent; GoFoton; Light Convers; LightTrans; MKS; OZ Opt Online; Santec; ThorLabs; UQDevices; YSL Photon}, organization = {IEEE; AdValue Photon; Amer Elements; Class5 Photon; Coherent; GoFoton; Light Convers; LightTrans; MKS; OZ Opt Online; Santec; ThorLabs; UQDevices; YSL Photon}, type = {Proceedings Paper}, abstract = {Coherent Frequency Shift Keying (CFSK) protocols paired with a quantum receiver can significantly optimize power and bandwidth efficiency of communication channels. We present our preliminary experimental data obtained with the CFSK quantum communication testbed. (c) 2019 The Author(s)}, isbn = {978-1-943580-57-6}, issn = {2160-9020}, author = {Burenkov, Ivan A. and Jabir, M. V. and El Idrissi, Driss and Battou, Abdella and Polyakov, Sergey V.} } @article { ISI:000489954500050, title = {Towards an in situ, full-power gauge of the focal-volume intensity of petawatt-class lasers}, journal = {Opt. Express}, volume = {27}, number = {21}, year = {2019}, month = {OCT 14}, pages = {30020-30030}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {About 50 years ago, Sarachick and Schappert {[}Phys. Rev. D. 1, 2738-2752 (1970)] showed that relativistic Thomson scattering leads to wavelength shifts that are proportional to the laser intensity. About 28 years later, Chen et al. {[}Nature 396, 653-655 (1998)] used these shifts to estimate their laser intensity near 10(18) W/cm(2). More recently, there have been several theoretical studies aimed at exploiting nonlinear Thomson scattering as a tool for direct measurement of intensities well into the relativistic regime. We present the first quantitative study of this approach for intensities between 10(18) and 10(19) W/cm(2). We show that the spectral shifts are in reasonable agreement with estimates of the peak intensity extracted from images of the focal area obtained at reduced power. Finally, we discuss the viability of the approach, its range of usefulness and how it might be extended to gauge intensities well in excess of 10(19) W/cm(2). (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {1094-4087}, doi = {10.1364/OE.27.030020}, author = {He, C. Z. and Longman, A. and Perez-Hernandez, J. A. and de Marco, M. and Salgado, C. and Zeraouli, G. and Gatti, G. and Roso, L. and Fedosejevs, R. and Hill, III, W. T.} } @article {14841, title = {Training of quantum circuits on a hybrid quantum computer}, journal = {Science Advances}, volume = {5}, year = {2019}, abstract = {Generative modeling is a flavor of machine learning with applications ranging from computer vision to chemical design. It is expected to be one of the techniques most suited to take advantage of the additional resources provided by near-term quantum computers. Here, we implement a data-driven quantum circuit training algorithm on the canonical Bars-and-Stripes dataset using a quantum-classical hybrid machine. The training proceeds by running parameterized circuits on a trapped ion quantum computer and feeding the results to a classical optimizer. We apply two separate strategies, Particle Swarm and Bayesian optimization to this task. We show that the convergence of the quantum circuit to the target distribution depends critically on both the quantum hardware and classical optimization strategy. Our study represents the first successful training of a high-dimensional universal quantum circuit and highlights the promise and challenges associated with hybrid learning schemes.

}, doi = {10.1126/sciadv.aaw9918}, url = {https://advances.sciencemag.org/content/5/10/eaaw9918}, author = {Zhu, D. and Linke, N. M. and Benedetti, M. and Landsman, K. A. and Nguyen, N. H. and Alderete, C. H. and Perdomo-Ortiz, A. and Korda, N. and Garfoot, A. and Brecque, C. and Egan, L. and Perdomo, O. and Monroe, C.} } @article {ISI:000456782500003, title = {Trapped Ion Quantum Information Processing with Squeezed Phonons}, journal = {Phys. Rev. Lett.}, volume = {122}, number = {3}, year = {2019}, month = {JAN 24}, pages = {030501}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Trapped ions offer a pristine platform for quantum computation and simulation, but improving their coherence remains a crucial challenge. Here, we propose and analyze a new strategy to enhance the coherent interactions in trapped ion systems via parametric amplification of the ions{\textquoteright} motion-by squeezing the collective motional modes (phonons), the spin-spin interactions they mediate can be significantly enhanced. We illustrate the power of this approach by showing how it can enhance collective spin states useful for quantum metrology, and how it can improve the speed and fidelity of two-qubit gates in multi-ion systems, important ingredients for scalable trapped ion quantum computation. Our results are also directly relevant to numerous other physical platforms in which spin interactions are mediated by bosons.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.122.030501}, author = {Ge, Wenchao and Sawyer, Brian C. and Britton, Joseph W. and Jacobs, Kurt and Bollinger, John J. and Foss-Feig, Michael} } @article { ISI:000498896500003, title = {Tunable Quantum Beat of Single Photons Enabled by Nonlinear Nanophotonics}, journal = {Phys. Rev. Appl.}, volume = {12}, number = {5}, year = {2019}, month = {NOV 22}, pages = {054054}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We demonstrate the tunable quantum beat of single photons through the co-development of core nonlinear nanophotonic technologies for frequency-domain manipulation of quantum states in a common physical platform. Spontaneous four-wave mixing in a nonlinear resonator is used to produce nondegenerate, quantum-correlated photon pairs. One photon from each pair is then frequency shifted, without degradation of photon statistics, using four-wave-mixing Bragg scattering in a second nonlinear resonator. Fine tuning of the applied frequency shift enables tunable quantum interference of the two photons as they are impinged on a beam splitter, with an oscillating signature that depends on their frequency difference. Our work showcases the potential of nonlinear nanophotonic devices as a valuable resource for photonic quantum-information science.}, issn = {2331-7019}, doi = {10.1103/PhysRevApplied.12.054054}, author = {Li, Qing and Singh, Anshuman and Lu, Xiyuan and Lawall, John and Verma, Varun and Mirin, Richard and Nam, Sae Woo and Srinivasan, Kartik} } @article {ISI:000460722900001, title = {Tunable surface plasmons in Weyl semimetals TaAs and NbAs}, journal = {Phys. Rev. B}, volume = {99}, number = {12}, year = {2019}, month = {MAR 4}, pages = {121401}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {By means of high-resolution electron energy loss spectroscopy, we investigate the low-energy excitation spectrum of transition-metal monopnictides hosting Weyl fermions. We observe gapped plasmonic modes in (001)-oriented surfaces of single crystals of NbAs and TaAs at 66 and 68 meV, respectively. Our findings are consistent with theory and we estimate an effective Coulomb interaction strength alpha(eff) approximate to 0.41 for both samples. We also demonstrate that the modification of the surface of transition-metal monopnictides by the adsorption of chemical species (in our case, oxygen and hydrocarbon fragments) changes the frequency of the plasmonic excitations, with a subsequent modification of the effective interaction strength in the 0.30-0.48 range. The remarkable dependence of plasmonic features on the presence of adsorbates paves the way for plasmonic sensors based on Weyl semimetals operating in the mid-infrared.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.121401}, author = {Chiarello, Gennaro and Hofmann, Johannes and Li, Zhilin and Fabio, Vito and Guo, Liwei and Chen, Xiaolong and S. Das Sarma and Politano, Antonio} } @article {ISI:000459152800093, title = {Twin-beam intensity-difference squeezing below 10 Hz}, journal = {Opt. Express}, volume = {27}, number = {4}, year = {2019}, month = {FEB 18}, pages = {4769-4780}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {We report the generation of strong, bright-beam intensity-difference squeezing down to measurement frequencies below 10 Hz. We generate two-mode squeezing in a four-wave mixing (4WM) process in Rb vapor, where the single-pass-gain nonlinear process does not require cavity locking and only relies on passive stability. We use diode laser technology and several techniques, including dual seeding, to remove the noise introduced by seeding the 4WM process as well as the background noise. Twin-beam intensity-difference squeezing down to frequencies limited only by the mechanical and atmospheric stability of the lab is achieved. These results should enable important low-frequency applications such as direct intensity-difference imaging with bright beams on integrating detectors. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {1094-4087}, doi = {10.1364/OE.27.004769}, author = {Wu, Meng-Chang and Schmittberger, Bonnie L. and Brewer, Nicholas R. and Speirs, Rory W. and Jones, Kevin M. and Lett, Paul D.} } @article { ISI:000489954500118, title = {Twin-beam sub-shot-noise raster-scanning microscope}, journal = {Opt. Express}, volume = {27}, number = {21}, year = {2019}, month = {OCT 14}, pages = {30810-30818}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {By exploiting the quantised nature of light, we demonstrate a sub-shot-noise scanning optical transmittance microscope. Our microscope demonstrates, with micron scale resolution, a factor of improvement in precision of 1.76(9) in transmittance estimation gained per probe photon relative to the theoretical model, a shot-noise-limited source of light, in an equivalent single-pass classical version of the same experiment using the same number of photons detected with a 90\% efficient detector. This would allow us to observe photosensitive samples with nearly twice the precision, without sacrificing image resolution or increasing optical power to improve signal-to-noise ratio. Our setup uses correlated twin-beams produced by parametric down-conversion, and a hybrid detection scheme comprising photon-counting-based feed-forward and a highly efficient CCD camera. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article{\textquoteright}s title, journal citation, and DOI.}, issn = {1094-4087}, doi = {10.1364/OE.27.030810}, author = {Sabines-Chesterking, J. and McMillan, A. R. and Moreau, P. A. and Joshi, S. K. and Knauer, S. and Johnston, E. and Rarity, J. G. and Matthews, J. C. F.} } @article {ISI:000484374000010, title = {Two are better than one}, journal = {Nat. Phys.}, volume = {15}, number = {9}, year = {2019}, month = {SEP}, pages = {882-883}, publisher = {NATURE PUBLISHING GROUP}, type = {News Item}, abstract = {Two-level quantum systems are routinely excited by resonant pump beams. Experiments now show resonant excitation through dichromatic, detuned pumps - providing a coherent control technique that will also aid single-photon emission from solid-state devices.}, issn = {1745-2473}, doi = {10.1038/s41567-019-0566-9}, author = {Solomon, Glenn S.} } @article { ISI:000492838300012, title = {Two-dimensional dilaton gravity theory and lattice Schwarzian theory}, journal = {Int. J. Mod. Phys. A}, volume = {34}, number = {29}, year = {2019}, month = {OCT 20}, pages = {1950176}, publisher = {WORLD SCIENTIFIC PUBL CO PTE LTD}, type = {Article}, abstract = {We report a holographic study of a two-dimensional dilaton gravity theory with the Dirichlet boundary condition for the cases of nonvanishing and vanishing cosmological constants. Our result shows that the boundary theory of the two-dimensional dilaton gravity theory with the Dirichlet boundary condition for the case of nonvanishing cosmological constants is the Schwarzian term coupled to a dilaton field, while for the case of vanishing cosmological constant, a theory does not have a kinetic term. We also include the higher derivative term R-2, where R is the scalar curvature that is coupled to a dilaton field. We find that the form of the boundary theory is not modified perturbatively. Finally, we show that a lattice holographic picture is realized up to the second-order perturbation of boundary cutoff epsilon(2) under a constant boundary dilaton field and the nonvanishing cosmological constant by identifying the lattice spacing a of a lattice Schwarzian theory with the boundary cutoff epsilon of the two-dimensional dilaton gravity theory.}, keywords = {Dilaton gravity theory, higher derivative term, isometry, lattice Schwarzian theory}, issn = {0217-751X}, doi = {10.1142/S0217751X19501768}, author = {Chu, Su-Kuan and Ma, Chen-Te and Wu, Chih-Hung} } @article {ISI:000455163900004, title = {Two-kind boson mixture honeycomb Hamiltonian of Bloch exciton-polaritons}, journal = {Phys. Rev. B}, volume = {99}, number = {4}, year = {2019}, month = {JAN 8}, pages = {045302}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The electronic band structure of a solid is a collection of allowed bands separated by forbidden bands, revealing the geometric symmetry of the crystal structures. Comprehensive knowledge of the band structure with band parameters explains intrinsic physical, chemical, and mechanical properties of the solid. Here we report the artificial polaritonic band structures of two-dimensional honeycomb lattices for microcavity exciton-polaritons using GaAs semiconductors in the wide-range detuning values, from cavity photonlike (red-detuned) to excitonlike (blue-detuned) regimes. In order to understand the experimental band structures and their band parameters, such as gap energies, bandwidths, hopping integrals, and density of states, we originally establish a polariton band theory within an augmented plane wave method with two-kind bosons, cavity photons trapped at the lattice sites, and freely moving excitons. In particular, this two-kind band theory is absolutely essential to elucidate the exciton effect in the band structures of blue-detuned exciton-polaritons, where the flattened excitonlike dispersion appears at larger in-plane momentum values captured in our experimental access window. We reach an excellent agreement between theory and experiments in all detuning values.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.045302}, author = {Pan, Haining and Winkler, K. and Powlowski, Mats and Xie, Ming and Schade, A. and Emmerling, M. and Kamp, M. and Klembt, S. and Schneider, C. and Byrnes, Tim and Hoefling, S. and Kim, Na Young} } @article {ISI:000482579500007, title = {Two-qubit entangling gates within arbitrarily long chains of trapped ions}, journal = {Phys. Rev. A}, volume = {100}, number = {2}, year = {2019}, month = {AUG 26}, pages = {022332}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Ion trap quantum computers are based on modulating the Coulomb interaction between atomic ion qubits using external forces. However, the spectral crowding of collective motional modes could pose a challenge to the control of such interactions for large numbers of qubits. Here, we show that high-fidelity quantum gate operations are still possible with very large trapped ion crystals by using a small and fixed number of motional modes, simplifying the scaling of ion trap quantum computers. We present analytical work that shows that gate operations need not couple to the motion of distant ions, allowing parallel entangling gates with a crosstalk error that falls off as the inverse cube of the distance between the pairs. We also experimentally demonstrate high-fidelity entangling gates on a fully connected set of seventeen Yb-171(+) qubits using simple laser pulse shapes that primarily couple to just a few modes.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.100.022332}, author = {Landsman, K. A. and Wu, Y. and Leung, P. H. and Zhu, D. and Linke, N. M. and Brown, K. R. and Duan, L. and Monroe, C.} } @article {ISI:000482583200042, title = {Two-Terminal and Multi-Terminal Designs for Next-Generation Quantized Hall Resistance Standards: Contact Material and Geometry}, journal = {IEEE Trans. Electron Devices}, volume = {66}, number = {9}, year = {2019}, month = {SEP}, pages = {3973-3977}, publisher = {IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC}, type = {Article}, abstract = {In this paper, we show that quantum Hall resistance measurements using two terminals may be as precise as four-terminal measurements when applying superconducting split contacts. The described sample designs eliminate resistance contributions of terminals and contacts such that the size and complexity of next-generation quantized Hall resistance devices can be significantly improved.}, keywords = {Epitaxial graphene (EG), multi-series (MS) contacts, quantized Hall resistance (QHR) standards, quantum Hall effect (QHE), superconducting contacts}, issn = {0018-9383}, doi = {10.1109/TED.2019.2926684}, author = {Kruskopf, Mattias and Rigosi, Albert F. and Panna, Alireza R. and Patel, Dinesh K. and Jin, Hanbyul and Marzano, Martina and Berilla, Michael and Newell, David B. and Elmquist, Randolph E.} } @article {ISI:000475499200001, title = {Universal level statistics of the out-of-time-ordered operator}, journal = {Phys. Rev. B}, volume = {100}, number = {3}, year = {2019}, month = {JUL 15}, pages = {035112}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The out-of-time-ordered correlator has been proposed as an indicator of chaos in quantum systems due to its simple interpretation in the semiclassical limit. In particular, its rate of possible exponential growth at h -> 0 is closely related to the classical Lyapunov exponent. Here we explore how this approach to quantum chaos relates to the random-matrix theoretical description. To do so, we introduce and study the level statistics of the logarithm of the out-of-time-ordered operator, (Lambda) over cap (t) = In (-{[}(x) over cap (t),(p) over cap (x)(0)](2) )/(2t), that we dub the {\textquoteleft}{\textquoteleft}Lyapunovian{{\textquoteright}{\textquoteright}} or {\textquoteleft}{\textquoteleft}Lyapunov operator{{\textquoteright}{\textquoteright}} for brevity. The Lyapunovian{\textquoteright}s level statistics is calculated explicitly for the quantum stadium billiard. It is shown that in the bulk of the filtered spectrum, this statistics perfectly aligns with the Wigner-Dyson distribution. One of the advantages of looking at the spectral statistics of this operator is that it has a well-defined semiclassical limit where it reduces to the matrix of uncorrelated classical finite-time Lyapunov exponents in a partitioned phase space. We provide a heuristic picture interpolating these two limits using Moyal quantum mechanics. Our results show that the Lyapunov operator may serve as a useful tool to characterize quantum chaos and in particular quantum-to-classical correspondence in chaotic systems by connecting the semiclassical Lyapunov growth at early times, when the quantum effects are weak, to universal level repulsion that hinges on strong quantum interference effects.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.035112}, author = {Rozenbaum, Efim B. and Ganeshan, Sriram and Galitski, Victor} } @article {ISI:000482956700001, title = {Universal logical gates with constant overhead: instantaneous Dehn twists for hyperbolic quantum codes}, journal = {Quantum}, volume = {3}, year = {2019}, month = {JUL 26}, publisher = {VEREIN FORDERUNG OPEN ACCESS PUBLIZIERENS QUANTENWISSENSCHAF}, type = {Article}, abstract = {A basic question in the theory of fault-tolerant quantum computation is to understand the fundamental resource costs for performing a universal logical set of gates on encoded qubits to arbitrary accuracy. Here we consider qubits encoded with constant space overhead (i.e. finite encoding rate) in the limit of arbitrarily large code distance d through the use of topological codes associated to triangulations of hyperbolic surfaces. We introduce explicit protocols to demonstrate how Dehn twists of the hyperbolic surface can be implemented on the code through constant depth unitary circuits, without increasing the space overhead. The circuit for a given Dehn twist consists of a permutation of physical qubits, followed by a constant depth local unitary circuit, where locality here is defined with respect to a hyperbolic metric that defines the code. Applying our results to the hyperbolic Fibonacci Turaev-Viro code implies the possibility of applying universal logical gate sets on encoded qubits through constant depth unitary circuits and with constant space overhead. Our circuits are inherently protected from errors as they map local operators to local operators while changing the size of their support by at most a constant factor; in the presence of noisy syndrome measurements, our results suggest the possibility of universal fault tolerant quantum computation with constant space overhead and time overhead of O(d/log d). For quantum circuits that allow parallel gate operations, this yields the optimal scaling of space-time overhead known to date.}, issn = {2521-327X}, author = {Lavasani, Ali and Zhu, Guanyu and Barkeshli, Maissam} } @article {ISI:000464281100001, title = {Universal Scattering of Ultracold Atoms and Molecules in Optical Potentials}, journal = {Atoms}, volume = {7}, number = {1}, year = {2019}, month = {MAR 15}, pages = {36}, publisher = {MDPI}, type = {Article}, abstract = {Universal collisions describe the reaction of molecules and atoms as dominated by long-range interparticle interactions. Here, we calculate the universal inelastic rate coefficients for a large group of ultracold polar molecules in their lower ro-vibrational states colliding with one of their constituent atoms. The rate coefficients are solely determined by values of the dispersion coefficient and reduced mass of the collisional system. We use the ab initio coupled-cluster linear response method to compute dynamic molecular polarizabilities and obtain the dispersion coefficients for some of the collisional partners and use values from the literature for others. Our polarizability calculations agree well with available experimental measurements. Comparison of our inelastic rate coefficients with results of numerically exact quantum-mechanical calculations leads us to conjecture that collisions with heavier atoms can be expected to be more universal.}, keywords = {chemical reactions, dispersion interaction, dynamic polorizability, ultracold atom-molecule collisions, universal model, van der Waals coefficients}, issn = {2218-2004}, doi = {10.3390/atoms7010036}, author = {Li, Hui and Li, Ming and Makrides, Constantinos and Petrov, Alexander and Kotochigova, Svetlana} } @article {ISI:000459572900004, title = {The US National Quantum Initiative}, journal = {Quantum Sci. Technol.}, volume = {4}, number = {2}, year = {2019}, month = {APR}, pages = {020504}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {Quantum technology exploits the unique quantum features of superposition, entanglement, and fundamental metrology metrics in order to create new opportunities in secure communication, high-precision sensing, and revolutionary computers. Quantum technology may eventually underlie a whole new technological infrastructure, much as the semiconductor revolution changed everything in last half of the 20th century. This paper summarizes the motivations and goals for the National Quantum Initiative (NQI) in the United States, and describes some of the processes that led to the introduction and passage of legislation in the US Congress to create the NQI.}, issn = {2058-9565}, doi = {10.1088/2058-9565/ab0441}, author = {Raymer, Michael G. and Monroe, Christopher} } @article { ISI:000515524300011, title = {Use of quantum effects as potential qualifying metrics for "quantum grade silicon"}, journal = {AIP Adv.}, volume = {9}, number = {12}, year = {2019}, month = {DEC 1}, pages = {125153}, publisher = {AMER INST PHYSICS}, type = {Article}, abstract = {Across solid state quantum information, material deficiencies limit performance through enhanced relaxation, charge defect motion, or isotopic spin noise. While classical measurements of device performance provide cursory guidance, specific qualifying metrics and measurements applicable to quantum devices are needed. For quantum applications, new material metrics, e.g., enrichment, are needed, while existing classical metrics such as mobility might be relaxed compared to conventional electronics. In this work, we examine locally grown silicon that is superior in enrichment, but inferior in chemical purity compared to commercial-silicon, as part of an effort to underpin the material standards needed for quantum grade silicon and establish a standard approach for the intercomparison of these materials. We use a custom, mass-selected ion beam deposition technique, which has produced isotopic enrichment levels up to 99.999 98\% Si-28, to isotopically enrich Si-28, but with chemical purity \>99.97\% due to the molecular beam epitaxy techniques used. From this epitaxial silicon, we fabricate top-gated Hall bar devices simultaneously on Si-28 and on the adjacent natural abundance Si substrate for intercomparison. Using standard-methods, we measure maximum mobilities of approximate to(1740 +/- 2) cm(2)/(V s) at an electron density of (2.7 x 10(12) +/- 3 x 10(8)) cm(-2) and approximate to(6040 +/- 3) cm(2)/(V s) at an electron density of (1.2 x 10(12) +/- 5 x 10(8)) cm(-2) at T = 1.9 K for devices fabricated on Si-28 and Si-nat, respectively. For magnetic fields B \> 2 T, both devices demonstrate well developed Shubnikov-de Haas oscillations in the longitudinal magnetoresistance. This provides the transport characteristics of isotopically enriched Si-28 and will serve as a benchmark for the classical transport of Si-28 at its current state and low temperature, epitaxially grown Si for quantum devices more generally. (C) 2019 Author(s).

}, doi = {10.1063/1.5128098}, author = {Ramanayaka, A. N. and Tang, Ke and Hagmann, J. A. and Kim, Hyun-Soo and Simons, D. S. and Richter, C. A. and Pomeroy, J. M.} } @article {ISI:000466372200007, title = {Validating and certifying stabilizer states}, journal = {Phys. Rev. A}, volume = {99}, number = {4}, year = {2019}, month = {APR 30}, pages = {042337}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We propose a measurement scheme that validates the preparation of an n-qubit stabilizer state. The scheme involves a measurement of n Pauli observables, a priori determined from the stabilizer state and which can be realized using single-qubit gates. Based on the proposed validation scheme, we derive an explicit expression for the worst-case fidelity, i.e., the minimum fidelity between the stabilizer state and any other state consistent with the measured data. We also show that the worst-case fidelity can be certified, with high probability, using O(n(2)) copies of the state.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.99.042337}, author = {Kalev, Amir and Kyrillidis, Anastasios and Linke, Norbert M.} } @article {14171, title = {Verified quantum information scrambling}, journal = {Nature}, year = {2019}, month = {03/2019}, doi = {10.1038/s41586-019-0952-6}, author = {Landsman, Kevin A. and Figgatt, Caroline and Schuster, T and Linke, Norbert M. and Yoshida, B and Yao, Norman Y. and Monroe, Christopher R.} } @article { ISI:000488514800006, title = {Weak Ergodicity Breaking and Quantum Many-Body Scars in Spin-1 XY Magnets}, journal = {Phys. Rev. Lett.}, volume = {123}, number = {14}, year = {2019}, month = {OCT 1}, pages = {147201}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study the spin-1 XY model on a hypercubic lattice in d dimensions and show that this well-known nonintegrable model hosts an extensive set of anomalous finite-energy-density eigenstates with remarkable properties. Namely, they exhibit subextensive entanglement entropy and spatiotemporal long-range order, both believed to be impossible in typical highly excited eigenstates of nonintegrable quantum many-body systems. While generic initial states are expected to thermalize, we show analytically that the eigenstates we construct lead to weak crgodicity breaking in the form of persistent oscillations of local observablcs following certain quantum quenches-in other words, these eigenstates provide an archetypal example of so-called quantum many-body scars. This Letter opens the door to the analytical study of the microscopic origin, dynamical signatures, and stability of such phenomena.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.123.147201}, author = {Schecter, Michael and Iadecola, Thomas} } @article { ISI:000490121400025, title = {Weakly bound molecules as sensors of new gravity like forces}, journal = {Sci Rep}, volume = {9}, year = {2019}, month = {OCT 15}, pages = {14807}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {Several extensions to the Standard Model of particle physics, including light dark matter candidates and unification theories predict deviations from Newton{\textquoteright}s law of gravitation. For macroscopic distances, the inverse-square law of gravitation is well confirmed by astrophysical observations and laboratory experiments. At micrometer and shorter length scales, however, even the state-of-the-art constraints on deviations from gravitational interaction, whether provided by neutron scattering or precise measurements of forces between macroscopic bodies, are currently many orders of magnitude larger than gravity itself. Here we show that precision spectroscopy of weakly bound molecules can be used to constrain non-Newtonian interactions between atoms. A proof-of-principle demonstration using recent data from photoassociation spectroscopy of weakly bound Yb-2 molecules yields constraints on these new interactions that are already close to state-of-the-art neutron scattering experiments. At the same time, with the development of the recently proposed optical molecular clocks, the neutron scattering constraints could be surpassed by at least two orders of magnitude.}, issn = {2045-2322}, doi = {10.1038/s41598-019-51346-y}, author = {Borkowski, Mateusz and Buchachenko, Alexei A. and Ciurylo, Roman and Julienne, Paul S. and Yamada, Hirotaka and Kikuchi, Yuu and Takasu, Yosuke and Takahashi, Yoshiro} } @article {ISI:000457732400002, title = {Wiedemann-Franz law and Fermi liquids}, journal = {Phys. Rev. B}, volume = {99}, number = {8}, year = {2019}, month = {FEB 4}, pages = {085104}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We consider in depth the applicability of the Wiedemann-Franz (WF) law, namely that the electronic thermal conductivity (K) is proportional to the product of the absolute temperature (T) and the electrical conductivity (a) in a metal with the constant of proportionality, the so-called Lorenz number L-0, being a materials-independent universal constant in all systems obeying the Fermi liquid (FL) paradigm. It has been often stated that the validity (invalidity) of the WF law is the hallmark of an FL {[}non-Fermi liquid (NFL)]. We consider, both in two (2D) and three (3D) dimensions, a system of conduction electrons at a finite temperature T coupled to a bath of acoustic phonons and quenched impurities, ignoring effects of electron-electron interactions. We find that the WF law is violated arbitrarily strongly with the effective Lorenz number vanishing at low temperatures as long as phonon scattering is stronger than impurity scattering. This happens both in 2D and in 3D for T < T-BG, where T-BG is the Bloch-Griineisen temperature of the system. In the absence of phonon scattering (or equivalently, when impurity scattering is much stronger than the phonon scattering), however, the WF law is restored at low temperatures even if the impurity scattering is mostly small angle forward scattering. Thus, strictly at T = 0 the WF law is always valid in a FL in the presence of infinitesimal impurity scattering. For strong phonon scattering, the WF law is restored for T > T-BG (or the Debye temperature T-D, whichever is lower) as in usual metals. At very high temperatures, thermal smearing of the Fermi surface causes the effective Lorenz number to go below L-0, manifesting a quantitative deviation from the WF law. Our paper establishes definitively that the uncritical association of an NFL behavior with the failure of the WF law is incorrect.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.99.085104}, author = {Lavasani, Ali and Bulmash, Daniel and S. Das Sarma} } @article { ISI:000433962700091, title = {A 3D-printed alkali metal dispenser}, journal = {REVIEW OF SCIENTIFIC INSTRUMENTS}, volume = {89}, number = {5}, year = {2018}, month = {MAY}, pages = {056101}, issn = {0034-6748}, doi = {10.1063/1.5023906}, author = {Norrgard, E. B. and Barker, D. S. and Fedchak, J. A. and Klimov, N. and Scherschligt, J. and Eckel, S.} } @article {ISI:000423432700002, title = {Absence of thermalization in finite isolated interacting Floquet systems}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {1}, year = {2018}, month = {JAN 29}, pages = {014311}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Conventional wisdom suggests that the long-time behavior of isolated interacting periodically driven (Floquet) systems is a featureless maximal-entropy state characterized by an infinite temperature. Efforts to thwart this uninteresting fixed point include adding sufficient disorder to realize a Floquet many-body localized phase or working in a narrow region of drive frequencies to achieve glassy nonthermal behavior at long time. Here we show that in clean systems the Floquet eigenstates can exhibit nonthermal behavior due to finite system size. We consider a one-dimensional system of spinless fermions with nearest-neighbor interactions where the interaction term is driven. Interestingly, even with no static component of the interaction, the quasienergy spectrum contains gaps and a significant fraction of the Floquet eigenstates, at all quasienergies, have nonthermal average doublon densities. We show that this nonthermal behavior arises due to emergent integrability at large interaction strength and discuss how the integrability breaks down with power-law dependence on system size.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.014311}, author = {Seetharam, Karthik and Titum, Paraj and Kolodrubetz, Michael and Refael, Gil} } @article { ISI:000454636100002, title = {Alkaline-Earth Atoms in Optical Tweezers}, journal = {PHYSICAL REVIEW X}, volume = {8}, number = {4}, year = {2018}, month = {DEC 28}, pages = {041055}, abstract = {We demonstrate single-shot imaging and narrow-line cooling of individual alkaline-earth atoms in optical tweezers; specifically, strontium trapped in 515.2-nm light. Our approach enables high-fidelity detection of single atoms by imaging photons from the broad singlet transition while cooling on the narrow intercombination line, and we extend this technique to highly uniform two-dimensional tweezer arrays with 121 sites. Cooling during imaging is based on a previously unobserved narrow-line Sisyphus mechanism, which we predict to be applicable in a wide variety of experimental situations. Further, we demonstrate optically resolved sideband cooling of a single atom to near the motional ground state of a tweezer, which is tuned to a magic-trapping configuration achieved by elliptical polarization. Finally, we present calculations, in agreement with our experimental results, that predict a linear-polarization and polarization-independent magic crossing at 520(2) nm and 500.65(50) nm, respectively. Our results pave the way for a wide range of novel experimental avenues based on individually controlled alkaline-earth atoms in tweezers-from fundamental experiments in atomic physics to quantum computing, simulation, and metrology.}, keywords = {Atomic and molecular physics, Quantum Information, Quantum Physics}, issn = {2160-3308}, doi = {10.1103/PhysRevX.8.041055}, author = {Cooper, Alexandre and Covey, Jacob P. and Madjarov, Ivaylo S. and Porsev, Sergey G. and Safronova, Marianna S. and Endres, Manuel} } @article { ISI:000442061000007, title = {Analogue stochastic gravity in strongly-interacting Bose-Einstein condensates}, journal = {ANNALS OF PHYSICS}, volume = {395}, year = {2018}, month = {AUG}, pages = {84-111}, keywords = {Collective modes, General relativity, Quantum fluids, Stochastic dynamics}, issn = {0003-4916}, doi = {10.1016/j.aop.2018.05.009}, author = {Keser, Aydin Cem and Galitski, Victor} } @article { ISI:000435333100006, title = {Anisotropic exciton transport in transition-metal dichalcogenides}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {24}, year = {2018}, month = {JUN 14}, pages = {245411}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.245411}, author = {Ghazaryan, Areg and Hafezi, Mohammad and Ghaemi, Pouyan} } @article { ISI:000452687700006, title = {Anomalous normal-state resistivity in superconducting La2-xCexCuO4: Fermi liquid or strange metal?}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {22}, year = {2018}, month = {DEC 10}, pages = {224503}, abstract = {We present experimental results for the in-plane resistivity of the electron-doped cuprate superconductor La2-xCexCuO4 above its transition temperature T-c as a function of Ce doping x and temperature. For the doping x between 0.11 and 0.17, where T-c varies from 30 K (x = 0.11) to 5 K (x = 0.17), we find that the resistivity shows a T-2 behavior for all values of doping over the measurement range from 70 to 250 K. The coefficient of the T-2 resistivity term decreases with increasing x following the trend in We analyze our data theoretically and posit that n-type cuprates are better thought of as strange metals. Although the quadratic temperature dependence appears to be in naive agreement with the Fermi-liquid (FL) expectations, the facts that the measured resistivity is large and approximate T-2 scattering dominates the resistivity even up to 400 K argue against a standard normal-metal FL picture being applicable. We discuss possible origins of the strange-metal behavior.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.224503}, author = {Sarkar, Tarapada and Greene, Richard L. and S. Das Sarma} } @article {10551, title = {Asymmetric Particle Transport and Light-Cone Dynamics Induced by Anyonic Statistics}, journal = {Phys. Rev. Lett.}, volume = {121}, year = {2018}, month = {Dec}, pages = {250404}, doi = {10.1103/PhysRevLett.121.250404}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.121.250404}, author = {Liu, Fangli and Garrison, James R. and Deng, Dong-Ling and Gong, Zhe-Xuan and Gorshkov, Alexey V.} } @article { ISI:000453488800011, title = {Atom-by-Atom Construction of a Cyclic Artificial Molecule in Silicon}, journal = {NANO LETTERS}, volume = {18}, number = {12}, year = {2018}, month = {DEC}, pages = {7502-7508}, abstract = {Hydrogen atoms on a silicon surface, H-Si (100), behave as a resist that can be patterned with perfect atomic precision using a scanning tunneling microscope. When a hydrogen atom is removed in this manner, the underlying silicon presents a chemically active site, commonly referred to as a dangling bond. It has been predicted that individual dangling bonds function as artificial atoms, which, if grouped together, can form designer molecules on the H-Si (100) surface. Here, we present an artificial ring structure molecule spanning three dimer rows, constructed from dangling bonds, and verified by spectroscopic measurement of its molecular orbitals. We found that removing 8 hydrogen atoms resulted in a molecular analog to 1,4-disilylene-hexasilabenzene (Si8H8). Scanning tunneling spectroscopic measurements reveal molecular pi and pi{*} orbitals that agree with those expected for the same molecule in a vacuum; this is validated by density functional theory calculations of the dangling bond system on a silicon slab that show direct links both to the experimental results and to calculations for the isolated molecule. We believe the unique electronic structure of artificial molecules constructed in this manner can be engineered to enable future molecule-based electronics, surface catalytic functionality, and templating for subsequent site selective deposition.}, keywords = {Artificial molecule, dangling bonds, feedback-controlled lithography, molecular orbitals}, issn = {1530-6984}, doi = {10.1021/acs.nanolett.8b02919}, author = {Wyrick, Jonathan and Wang, Xiqiao and Namboodiri, Pradeep and Schmucker, Scott W. and Kashid, Ranjit V. and Silver, Richard M.} } @article { ISI:000423426200008, title = {Atomic properties of actinide ions with particle-hole configurations}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {1}, year = {2018}, month = {JAN 25}, pages = {012511}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.012511}, author = {Safronova, M. S. and Safronova, U. I. and Kozlov, M. G.} } @article { ISI:000428774000001, title = {Attosecond transient absorption spectrum of argon at the L-2,L-3 edge}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {3}, year = {2018}, month = {MAR 30}, pages = {031407}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.031407}, author = {Chew, Andrew and Douguet, Nicolas and Cariker, Coleman and Li, Jie and Lindroth, Eva and Ren, Xiaoming and Yin, Yanchun and Argenti, Luca and Hill, III, Wendell T. and Chang, Zenghu} } @article { ISI:000433912300001, title = {An autonomous single-piston engine with a quantum rotor}, journal = {QUANTUM SCIENCE AND TECHNOLOGY}, volume = {3}, number = {3}, year = {2018}, month = {JUL}, pages = {UNSP 035008}, keywords = {autonomous heat engine, quantum thermodynamics, rotor heat engine}, issn = {2058-9565}, doi = {10.1088/2058-9565/aac40d}, author = {Roulet, Alexandre and Nimmrichter, Stefan and Taylor, Jacob M.} } @article { ISI:000450960700005, title = {Bell monogamy relations in arbitrary qubit networks}, journal = {PHYSICAL REVIEW A}, volume = {98}, number = {5}, year = {2018}, month = {NOV 20}, pages = {052325}, issn = {2469-9926}, doi = {10.1103/PhysRevA.98.052325}, author = {Tran, M. C. and Ramanathan, R. and McKague, M. and Kaszlikowski, D. and Paterek, T.} } @article {ISI:000431374900011, title = {Beyond triplet: Unconventional superconductivity in a spin-3/2 topological semimetal}, journal = {SCIENCE ADVANCES}, volume = {4}, number = {4}, year = {2018}, month = {APR}, pages = {eaao4513}, publisher = {AMER ASSOC ADVANCEMENT SCIENCE}, type = {Article}, abstract = {In all known fermionic superfluids, Cooper pairs are composed of spin-1/2 quasi-particles that pair to formeither spinsinglet or spin-triplet bound states. The {\textquoteleft}{\textquoteleft}spin{{\textquoteright}{\textquoteright}} of a Bloch electron, however, is fixed by the symmetries of the crystal and the atomic orbitals from which it is derived and, in some cases, can behave as if it were a spin-3/2 particle. The superconducting state of such a system allows pairing beyond spin-triplet, with higher spin quasi-particles combining to formquintet or septet pairs. We report evidence of unconventional superconductivity emerging from a spin-3/2 quasi-particle electronic structure in the half-Heusler semimetal YPtBi, a low-carrier density noncentrosymmetric cubic material with a high symmetry that preserves the p-like j = 3/2 manifold in the Bi-based Gamma(8) band in the presence of strong spin-orbit coupling. With a striking linear temperature dependence of the London penetration depth, the existence of line nodes in the superconducting order parameter Delta is directly explained by a mixed-parity Cooper pairing model with high total angular momentum, consistent with a high-spin fermionic superfluid state. We propose a k.p model of the j = 3/2 fermions to explain how a dominant J = 3 septet pairing state is the simplest solution that naturally produces nodes in the mixed even-odd parity gap. Together with the underlying topologically nontrivial band structure, the unconventional pairing in this system represents a truly novel form of superfluidity that has strong potential for leading the development of a new series of topological superconductors.

}, issn = {2375-2548}, doi = {10.1126/sciadv.aao4513}, author = {Kim, Hyunsoo and Wang, Kefeng and Nakajima, Yasuyuki and Hu, Rongwei and Ziemak, Steven and Syers, Paul and Wang, Limin and Hodovanets, Halyna and Denlinger, Jonathan D. and Brydon, Philip M. R. and Agterberg, Daniel F. and Tanatar, Makariy A. and Prozorov, Ruslan and Paglione, Johnpierre} } @article { ISI:000419615700007, title = {Building topological quantum circuits: Majorana nanowire junctions}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {4}, year = {2018}, month = {JAN 9}, pages = {045410}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.045410}, author = {Stanescu, Tudor D. and S. Das Sarma} } @article { ISI:000433001000002, title = {Cavity-Enhanced Optical Readout of a Single Solid-State Spin}, journal = {PHYSICAL REVIEW APPLIED}, volume = {9}, number = {5}, year = {2018}, month = {MAY 9}, pages = {054013}, issn = {2331-7019}, doi = {10.1103/PhysRevApplied.9.054013}, author = {Sun, Shuo and Kim, Hyochul and Solomon, Glenn S. and Waks, Edo} } @article { ISI:000444740400001, title = {Challenges to miniaturizing cold atom technology for deployable vacuum metrology}, journal = {METROLOGIA}, volume = {55}, number = {5}, year = {2018}, month = {OCT}, pages = {S182-S193}, keywords = {cold atom sensing, quantum-SI, vacuum metrology}, issn = {0026-1394}, doi = {10.1088/1681-7575/aadbe4}, author = {Eckel, Stephen and Barker, Daniel S. and Fedchak, James A. and Klimov, Nikolai N. and Norrgard, Eric and Scherschligt, Julia and Makrides, Constantinos and Tiesinga, Eite} } @article { ISI:000452326000001, title = {Chiral anomaly without Landau levels: From the quantum to the classical regime}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {24}, year = {2018}, month = {DEC 6}, pages = {245109}, abstract = {We study the chiral anomaly in disordered Weyl semimetals, where the broken translational symmetry prevents the direct application of Nielsen and Ninomiya{\textquoteright}s mechanism and disorder is strong enough that quantum effects are important. In the weak disorder regime, there exist rare regions of the random potential where the disorder strength is locally strong, which gives rise to quasilocalized resonances and their effect on the chiral anomaly is unknown. We numerically show that these resonant states do not affect the chiral anomaly only in the case of a single Weyl node. At energies away from the Weyl point, or with strong disorder where one is deep in the diffusive regime, the chiral Landau level itself is not well defined and the semiclassical treatment is not justified. In this limit, we analytically use the supersymmetry method and find that the Chern-Simons term in the effective action which is not present in nontopological systems gives rise to a nonzero average level velocity which implies chiral charge pumping. We numerically establish that the nonzero average level velocity serves as an indicator of the chiral anomaly in the diffusive limit.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.245109}, author = {Lee, Junhyun and Pixley, J. H. and Sau, Jay D.} } @article { ISI:000445336700001, title = {Chiral Majorana fermion modes on the surface of superconducting topological insulators}, journal = {EPL}, volume = {123}, number = {4}, year = {2018}, month = {AUG}, pages = {47005}, issn = {0295-5075}, doi = {10.1209/0295-5075/123/47005}, author = {Chiu, Ching-Kai and Bian, Guang and Zheng, Hao and Yin, Jia-Xin and Zhang, Songtian S. and Sanchez, D. S. and Belopolski, I and Xu, Su-Yang and Hasan, M. Zahid} } @article { ISI:000423228300001, title = {Chiral spin currents in a trapped-ion quantum simulator using Floquet engineering}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {1}, year = {2018}, month = {JAN 19}, pages = {010302}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.010302}, author = {Grass, Tobias and Celi, Alessio and Pagano, Guido and Lewenstein, Maciej} } @article { ISI:000452324400004, title = {Chiral supercurrent through a quantum Hall weak link}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {21}, year = {2018}, month = {DEC 6}, pages = {214504}, abstract = {We use an effective model to calculate properties of the supercurrent carried by chiral edge states of a quantum Hall weak link. This {\textquoteleft}{\textquoteleft}chiral{{\textquoteright}{\textquoteright}} supercurrent is qualitatively distinct from the usual Josephson supercurrent in that it cannot be mediated by a single edge alone, i.e., both right- and left-going edges are needed. Moreover, the chiral supercurrent was previously shown to obey an unusual current-phase relation with period 2 phi(0) = h/e, which is twice the period of conventional Josephson junctions. We show that the {\textquoteleft}{\textquoteleft}chiral{{\textquoteright}{\textquoteright}} nature of this supercurrent is sharply defined, and is robust to interactions to infinite order in perturbation theory. We compare our results with recent experimental findings {[}Amet et al., Science 352 966 (2016)] and find that quantitative agreement in the magnitude of the supercurrent can be attained by making reasonable but critical assumptions about the superconductor quantum Hall interface.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.214504}, author = {Alavirad, Yahya and Lee, Junhyun and Lin, Ze-Xun and Sau, Jay D.} } @article { ISI:000441668600006, title = {Clock-related properties of Lu+}, journal = {PHYSICAL REVIEW A}, volume = {98}, number = {2}, year = {2018}, month = {AUG 14}, pages = {022509}, issn = {2469-9926}, doi = {10.1103/PhysRevA.98.022509}, author = {Porsev, S. G. and Safronova, U. I. and Safronova, M. S.} } @article { ISI:000428617600038, title = {A coherent spin-photon interface in silicon}, journal = {NATURE}, volume = {555}, number = {7698}, year = {2018}, month = {MAR 29}, pages = {599+}, issn = {0028-0836}, doi = {10.1038/nature25769}, author = {Mi, X. and Benito, M. and Putz, S. and Zajac, D. M. and Taylor, J. M. and Burkard, Guido and Petta, J. R.} } @article { ISI:000448933900004, title = {Collective Effects in Casimir-Polder Forces}, journal = {PHYSICAL REVIEW LETTERS}, volume = {121}, number = {18}, year = {2018}, month = {NOV 1}, pages = {183605}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.121.183605}, author = {Sinha, Kanupriya and Venkatesh, B. Prasanna and Meystre, Pierre} } @article { ISI:000423428400002, title = {Conductance interference in a superconducting Coulomb blockaded Majorana ring}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {3}, year = {2018}, month = {JAN 26}, pages = {035310}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.035310}, author = {Chiu, Ching-Kai and Sau, Jay D. and S. Das Sarma} } @article { ISI:000449292600001, title = {Configuration-controlled many-body localization and the mobility emulsion}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {17}, year = {2018}, month = {NOV 2}, pages = {174201}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.174201}, author = {Schecter, Michael and Iadecola, Thomas and S. Das Sarma} } @article { ISI:000452675100001, title = {Confocal laser scanning microscopy for rapid optical characterization of graphene}, journal = {COMMUNICATIONS PHYSICS}, volume = {1}, year = {2018}, month = {NOV 20}, pages = {83}, issn = {2399-3650}, doi = {10.1038/s42005-018-0084-6}, author = {Panchal, Vishal and Yang, Yanfei and Cheng, Guangjun and Hu, Jiuning and Kruskopf, Mattias and Liu, I, Chieh- and Rigosi, Albert F. and Melios, Christos and Walker, Angela R. Hight and Newell, David B. and Kazakova, Olga and Elmquist, Randolph E.} } @article { ISI:000423614600001, title = {Controlling the layer localization of gapless states in bilayer graphene with a gate voltage}, journal = {2D MATERIALS}, volume = {5}, number = {2}, year = {2018}, month = {APR}, pages = {025006}, keywords = {bilayer graphene, graphene, topologically protected states}, issn = {2053-1583}, doi = {10.1088/2053-1583/aaa490}, author = {Jaskolski, W. and Pelc, M. and Bryant, Garnett W. and Chico, Leonor and Ayuela, A.} } @article { ISI:000432031700004, title = {Cooper pair induced frustration and nematicity of two-dimensional magnetic adatom lattices}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {17}, year = {2018}, month = {MAY 10}, pages = {174412}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.174412}, author = {Schecter, Michael and Syljuasen, Olav F. and Paaske, Jens} } @article { ISI:000449713800005, title = {Coupling quantum emitters in WSe2 monolayers to a metal-insulator-metal waveguide}, journal = {APPLIED PHYSICS LETTERS}, volume = {113}, number = {19}, year = {2018}, month = {NOV 5}, pages = {191105}, issn = {0003-6951}, doi = {10.1063/1.5045727}, author = {Dutta, Subhojit and Cai, Tao and Buyukkaya, Mustafa Atabey and Barik, Sabyasachi and Aghaeimeibodi, Shahriar and Waks, Edo} } @conference { ISI:000450863900003, title = {Coupling single defects in 2D semiconductor to a silver nanowire}, booktitle = {2D PHOTONIC MATERIALS AND DEVICES}, series = {Proceedings of SPIE}, volume = {10534}, year = {2018}, note = {Conference on 2D Photonic Materials and Devices, San Francisco, CA, JAN 29-31, 2018}, pages = {105340F}, keywords = {2D semiconductors, defect emission, silver nanowire, Surface plasmon polaritons, transition metal dichalcogenide, tungsten diselenide}, isbn = {978-1-5106-1554-0; 978-1-5106-1553-3}, issn = {0277-786X}, doi = {10.1117/12.2285431}, author = {Cai, Tao and Dutta, Subhojit and Aghaeimeibodi, Shahriar and Yang, Zhili and Nah, Sanghee and Fourkas, John T. and Waks, Edo}, editor = {Majumdar, A and Xu, X and Hendrickson, JR} } @article { ISI:000423433700007, title = {Crosstalk error correction through dynamical decoupling of single-qubit gates in capacitively coupled singlet-triplet semiconductor spin qubits}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {4}, year = {2018}, month = {JAN 29}, pages = {045431}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.045431}, author = {Buterakos, Donovan and Throckmorton, Robert E. and S. Das Sarma} } @article {9151, title = {Dark State Optical Lattice with a Subwavelength Spatial Structure}, journal = {Phys. Rev. Lett.}, volume = {120}, year = {2018}, month = {Feb}, pages = {083601}, doi = {10.1103/PhysRevLett.120.083601}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.120.083601}, author = {Wang, Y. and Subhankar, S. and Bienias, P and {\L}{\k a}cki, M. and Tsui, T-C. and Baranov, M. A. and Gorshkov, A. V. and Zoller, P. and Porto, J. V. and Rolston, S. L.} } @article { ISI:000439334800001, title = {Demonstration of a Bayesian quantum game on an ion-trap quantum computer}, journal = {QUANTUM SCIENCE AND TECHNOLOGY}, volume = {3}, number = {4}, year = {2018}, month = {OCT}, pages = {UNSP 045002}, keywords = {ion traps, quantum computation, quantum games}, issn = {2058-9565}, doi = {10.1088/2058-9565/aacf0e}, author = {Solmeyer, Neal and Linke, Norbert M. and Figgatt, Caroline and Landsman, Kevin A. and Balu, Radhakrishnan and Siopsis, George and Monroe, C.} } @article { ISI:000428966400004, title = {Demonstration of a Sensitive Method to Measure Nuclear-Spin-Dependent Parity Violation}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {14}, year = {2018}, month = {APR 2}, pages = {142501}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.142501}, author = {Altuntas, Emine and Ammon, Jeffrey and Cahn, Sidney B. and DeMille, David} } @article { ISI:000429937300002, title = {Demonstration of Protection of a Superconducting Qubit from Energy Decay}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {15}, year = {2018}, month = {APR 13}, pages = {150503}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.150503}, author = {Lin, Yen-Hsiang and Nguyen, Long B. and Grabon, Nicholas and San Miguel, Jonathan and Pankratova, Natalia and Manucharyan, Vladimir E.} } @article { ISI:000443094300002, title = {Diluted magnetic Dirac-Weyl materials: Susceptibility and ferromagnetism in three-dimensional chiral gapless semimetals}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {6}, year = {2018}, month = {AUG 29}, pages = {064425}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.064425}, author = {Park, Sanghyun and Min, Hongki and Hwang, E. H. and S. Das Sarma} } @article { ISI:000447621900002, title = {Dimensionally mixed coupled collective modes}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {16}, year = {2018}, month = {OCT 18}, pages = {161304}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.161304}, author = {Hwang, E. H. and Hu, Ben Yu-Kuang and S. Das Sarma} } @article {ISI:000427010500002, title = {Disorder-induced half-integer quantized conductance plateau in quantum anomalous Hall insulator-superconductor structures}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {10}, year = {2018}, month = {MAR 9}, pages = {100501}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {A weak superconducting proximity effect in the vicinity of the topological transition of a quantum anomalous Hall system has been proposed as a venue to realize a topological superconductor (TSC) with chiral Majorana edge modes (CMEMs). A recent experiment {[}Science 357, 294 (2017)] claimed to have observed such CMEMs in the form of a half-integer quantized conductance plateau in the two-terminal transport measurement of a quantum anomalous Hall-superconductor junction. Although the presence of a superconducting proximity effect generically splits the quantum Hall transition into two phase transitions with a gapped TSC in between, in this Rapid Communication we propose that a nearly flat conductance plateau, similar to that expected from CMEMs, can also arise from the percolation of quantum Hall edges well before the onset of the TSC or at temperatures much above the TSC gap. Our Rapid Communication, therefore, suggests that, in order to confirm the TSC, it is necessary to supplement the observation of the half-quantized conductance plateau with a hard superconducting gap (which is unlikely for a disordered system) from the conductance measurements or the heat transport measurement of the transport gap. Alternatively, the half-quantized thermal conductance would also serve as a smoking-gun signature of the TSC.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.100501}, author = {Huang, Yingyi and Setiawan, F. and Sau, Jay D.} } @article { ISI:000444557300003, title = {Dissipation-enabled fractional Josephson effect}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {12}, year = {2018}, month = {SEP 12}, pages = {125124}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.125124}, author = {Sticlet, Doru and Sau, Jay D. and Akhmerov, Anton} } @article {ISI:000426249900005, title = {Dissipation-induced dipole blockade and antiblockade in driven Rydberg systems}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {2}, year = {2018}, month = {FEB 28}, pages = {023424}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study theoretically and experimentally the competing blockade and antiblockade effects induced by spontaneously generated contaminant Rydberg atoms in driven Rydberg systems. These contaminant atoms provide a source of strong dipole-dipole interactions and play a crucial role in the system{\textquoteright}s behavior. We study this problem theoretically using two different approaches. The first is a cumulant expansion approximation, in which we ignore third-order and higher connected correlations. Using this approach for the case of resonant drive, a many-body blockade radius picture arises, and we find qualitative agreement with previous experimental results. We further predict that as the atomic density is increased, the Rydberg population{\textquoteright}s dependence on Rabi frequency will transition from quadratic to linear dependence at lower Rabi frequencies. We study this behavior experimentally by observing this crossover at two different atomic densities. We confirm that the larger density system has a smaller crossover Rabi frequency than the smaller density system. The second theoretical approach is a set of phenomenological inhomogeneous rate equations. We compare the results of our rate-equation model to the experimental observations {[}E. A. Goldschmidt et al., Phys. Rev. Lett. 116, 113001 (2016)] and find that these rate equations provide quantitatively good scaling behavior of the steady-state Rydberg population for both resonant and off-resonant drives.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.023424}, author = {Young, Jeremy T. and Boulier, Thomas and Magnan, Eric and Goldschmidt, Elizabeth A. and Wilson, Ryan M. and Rolston, Steven L. and Porto, James V. and Gorshkov, Alexey V.} } @article { ISI:000434209100002, title = {Distinguishing topological Majorana bound states from trivial Andreev bound states: Proposed tests through differential tunneling conductance spectroscopy}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {21}, year = {2018}, month = {JUN 5}, pages = {214502}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.214502}, author = {Liu, Chun-Xiao and Sau, Jay D. and S. Das Sarma} } @article { ISI:000439744700003, title = {Distributed Quantum Metrology with Linear Networks and Separable Inputs}, journal = {PHYSICAL REVIEW LETTERS}, volume = {121}, number = {4}, year = {2018}, month = {JUL 25}, pages = {043604}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.121.043604}, author = {Ge, Wenchao and Jacobs, Kurt and Eldredge, Zachary and Gorshkov, V, Alexey and Foss-Feig, Michael} } @article { ISI:000432971400001, title = {Does a Single Eigenstate Encode the Full Hamiltonian?}, journal = {PHYSICAL REVIEW X}, volume = {8}, number = {2}, year = {2018}, month = {APR 30}, pages = {021026}, issn = {2160-3308}, doi = {10.1103/PhysRevX.8.021026}, author = {Garrison, James R. and Grover, Tarun} } @article { ISI:000419476900017, title = {Dressed infrared quantum information}, journal = {PHYSICAL REVIEW D}, volume = {97}, number = {2}, year = {2018}, month = {JAN 8}, pages = {025007}, issn = {2470-0010}, doi = {10.1103/PhysRevD.97.025007}, author = {Carney, Daniel and Chaurette, Laurent and Neuenfeld, Dominik and Semenoff, Gordon Walter} } @article {10101, title = {Dynamical Phase Transitions in Sampling Complexity}, journal = {Phys. Rev. Lett.}, volume = {121}, year = {2018}, month = {Jul}, pages = {030501}, doi = {10.1103/PhysRevLett.121.030501}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.121.030501}, author = {Deshpande, Abhinav and Fefferman, Bill and Tran, Minh C. and Foss-Feig, Michael and Gorshkov, Alexey V.} } @article {10476, title = {Dynamo Effect and Turbulence in Hydrodynamic Weyl Metals}, journal = {Phys. Rev. Lett.}, volume = {121}, year = {2018}, month = {Oct}, pages = {176603}, doi = {10.1103/PhysRevLett.121.176603}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.121.176603}, author = {Galitski, Victor and Kargarian, Mehdi and Syzranov, Sergey} } @article { ISI:000447148100009, title = {Effect of device design on charge offset drift in Si/SiO2 single electron devices}, journal = {JOURNAL OF APPLIED PHYSICS}, volume = {124}, number = {14}, year = {2018}, month = {OCT 14}, pages = {144302}, issn = {0021-8979}, doi = {10.1063/1.5048013}, author = {Hu, Binhui and Ochoa, Erick D. and Sanchez, Daniel and Perron, Justin K. and Zimmerman, Neil M. and Stewart, Jr., M. D.} } @article { ISI:000437843700001, title = {Effective renormalized multi-body interactions of harmonically confined ultracold neutral bosons (vol 14, 053037, 2012)}, journal = {NEW JOURNAL OF PHYSICS}, volume = {20}, year = {2018}, month = {JUL 6}, pages = {079501}, issn = {1367-2630}, doi = {10.1088/1367-2630/aacf78}, author = {Johnson, P. R. and Blume, D. and Yin, X. Y. and Flynn, W. F. and Tiesinga, E.} } @article { ISI:000439543800001, title = {Effective theory approach to the Schrodinger-Poisson problem in semiconductor Majorana devices}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {3}, year = {2018}, month = {JUL 24}, pages = {035428}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.035428}, author = {Woods, Benjamin D. and Stanescu, Tudor D. and S. Das Sarma} } @article {ISI:000430601100005, title = {Effects of resonant-laser excitation on the emission properties in a single quantum dot}, journal = {OPTICA}, volume = {5}, number = {4}, year = {2018}, month = {APR 20}, pages = {354-359}, publisher = {OPTICAL SOC AMER}, type = {Article}, abstract = {While many solid-state emitters can be optically excited non-resonantly, resonant excitation is necessary for many quantum information protocols as it often maximizes the non-classicality of the emitted light. Here, we study the resonance fluorescence in a solid-state system-a quantum dot-with the addition of weak, non-resonant light. In the inelastic scattering regime, changes in the resonance fluorescence intensity and linewidth are linked to both the non-resonant and resonant laser powers. Details of the intensity change indicate that charge-carrier loss from the quantum dot is resonant laser. As we enter the Mollow triplet regime, this resonant laser loss term rate is approximately 1/50 ns(-1). This work further clarifies resonance fluorescence in solid-state systems and will aid in the further improvement of solid-state non-classical light sources.}, \%\%Address = {2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA}, issn = {2334-2536}, doi = {10.1364/OPTICA.5.000354}, author = {Gazzano, O. and Huber, T. and Loo, V and Polyakov, S. and Flagg, E. B. and Solomon, G. S.} } @article { ISI:000425507400010, title = {Electro-mechano-optical detection of nuclear magnetic resonance}, journal = {OPTICA}, volume = {5}, number = {2}, year = {2018}, month = {FEB 20}, pages = {152-158}, issn = {2334-2536}, doi = {10.1364/OPTICA.5.000152}, author = {Takeda, Kazuyuki and Nagasaka, Kentaro and Noguchi, Atsushi and Yamazaki, Rekishu and Nakamura, Yasunobu and Iwase, Eiji and Taylor, Jacob M. and Usami, Koji} } @article { ISI:000435442300004, title = {Electronic hydrodynamics and the breakdown of the Wiedemann-Franz and Mott laws in interacting metals}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {24}, year = {2018}, month = {JUN 18}, pages = {245128}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.245128}, author = {Lucas, Andrew and S. Das Sarma} } @article { ISI:000428501200005, title = {Electronic sound modes and plasmons in hydrodynamic two-dimensional metals}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {11}, year = {2018}, month = {MAR 28}, pages = {115449}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.115449}, author = {Lucas, Andrew and S. Das Sarma} } @article { ISI:000447310800001, title = {Electrooptomechanical Equivalent Circuits for Quantum Transduction}, journal = {PHYSICAL REVIEW APPLIED}, volume = {10}, number = {4}, year = {2018}, month = {OCT 15}, pages = {044036}, issn = {2331-7019}, doi = {10.1103/PhysRevApplied.10.044036}, author = {Zeuthen, Emil and Schliesser, Albert and Taylor, Jacob M. and Sorensen, Anders S.} } @article { ISI:000450048400053, title = {Emergence of multi-body interactions in a fermionic lattice clock}, journal = {NATURE}, volume = {563}, number = {7731}, year = {2018}, month = {NOV 15}, pages = {369+}, issn = {0028-0836}, doi = {10.1038/s41586-018-0661-6}, author = {Goban, A. and Hutson, R. B. and Marti, G. E. and Campbell, S. L. and Perlin, M. A. and Julienne, P. S. and D{\textquoteright}Incao, J. P. and Rey, A. M. and Ye, J.} } @article { ISI:000438672400001, title = {Energy-level statistics in strongly disordered systems with power-law hopping}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {1}, year = {2018}, month = {JUL 16}, pages = {014201}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.014201}, author = {Titum, Paraj and Quito, Victor L. and Syzranov, V, Sergey} } @conference { ISI:000450231900106, title = {Epitaxial Graphene for High-Current QHE Resistance Standards}, booktitle = {2018 CONFERENCE ON PRECISION ELECTROMAGNETIC MEASUREMENTS (CPEM 2018)}, year = {2018}, note = {Conference on Precision Electromagnetic Measurements (CPEM), Paris, FRANCE, JUL 08-13, 2018}, keywords = {epitaxial graphene, face-to-graphite (FTG), polymer-assisted growth (PASG), quantum resistance metrology}, isbn = {978-1-5386-0974-3}, author = {Kruskopf, Mattias and Hu, Jiuning and Wu, Bi-Yi and Yang, Yanfei and Lee, Hsin-Yen and Rigosi, Albert F. and Newell, David B. and Elmquist, Randolph E.} } @article { ISI:000439337700001, title = {Epitaxial graphene for quantum resistance metrology}, journal = {METROLOGIA}, volume = {55}, number = {4}, year = {2018}, month = {AUG}, pages = {R27-R36}, keywords = {epitaxial graphene, quantum Hall effect, quantum resistance metrology}, issn = {0026-1394}, doi = {10.1088/1681-7575/aacd23}, author = {Kruskopf, Mattias and Elmquist, Randolph E.} } @conference { ISI:000450231900084, title = {Epitaxial Graphene p-n Junctions}, booktitle = {2018 CONFERENCE ON PRECISION ELECTROMAGNETIC MEASUREMENTS (CPEM 2018)}, year = {2018}, note = {Conference on Precision Electromagnetic Measurements (CPEM), Paris, FRANCE, JUL 08-13, 2018}, keywords = {epitaxial graphene, graphene p-n junction, quantum Hall effect, resistance standard}, isbn = {978-1-5386-0974-3}, author = {Hu, Jiuning and Kruskopf, Mattias and Yang, Yanfei and Wu, Bi-Yi and Tian, Jifa and Panna, Alireza and Rigosi, Albert F. and Lee, Hsin-Yen and Payagala, Shamith and Jones, George R. and Kraft, Marlin E. and Jarrett, Dean G. and Watanabe, Kenji and Taniguchi, Takashi and Elmquist, Randolph E. and Newell, David B.} } @article { ISI:000451073900001, title = {Equations of state from individual one-dimensional Bose gases}, journal = {NEW JOURNAL OF PHYSICS}, volume = {20}, year = {2018}, month = {NOV 23}, pages = {113032}, abstract = {We trap individual 1D Bose gases and obtain the associated equation of state by combining calibrated confining potentials with in situ density profiles. Our observations agree well with the exact Yang- Yang 1D thermodynamic solutions under the local density approximation. We find that our final 1D system undergoes inefficient evaporative cooling that decreases the absolute temperature, but monotonically reduces a degeneracy parameter.}, keywords = {atomic physics, equation of state, one-dimensonal Bose gas, quantum gases}, issn = {1367-2630}, doi = {10.1088/1367-2630/aaef9b}, author = {Salces-Carcoba, F. and Billington, C. J. and Putra, A. and Yue, Y. and Sugawa, S. and Ian B Spielman} } @article { ISI:000419616600003, title = {Equivalence principle for quantum systems: dephasing and phase shift of free-falling particles}, journal = {CLASSICAL AND QUANTUM GRAVITY}, volume = {35}, number = {3}, year = {2018}, month = {FEB 8}, pages = {035011}, keywords = {equivalence principle, free fall, gravitational phase shift, gravitational quantum physics}, issn = {0264-9381}, doi = {10.1088/1361-6382/aaa0e8}, author = {Anastopoulos, C. and Hu, B. L.} } @article { ISI:000437110200003, title = {Error correction for gate operations in systems of exchange-coupled singlet-triplet qubits in double quantum dots}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {3}, year = {2018}, month = {JUL 3}, pages = {035406}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.035406}, author = {Buterakos, Donovan and Throckmorton, Robert E. and S. Das Sarma} } @article { ISI:000433265900009, title = {Examining epitaxial graphene surface conductivity and quantum Hall device stability with Parylene passivation}, journal = {MICROELECTRONIC ENGINEERING}, volume = {194}, year = {2018}, month = {JUL 5}, pages = {51-55}, keywords = {epitaxial graphene, Parylene, quantum Hall effect, Surface conductivity, Transport mobility}, issn = {0167-9317}, doi = {10.1016/j.mee.2018.03.004}, author = {Rigosi, Albert F. and Liu, Chieh-I and Wu, Bi Yi and Lee, Hsin-Yen and Kruskopf, Mattias and Yang, Yanfei and Hill, Heather M. and Hu, Jiuning and Bittle, Emily G. and Obrzut, Jan and Walker, Angela R. Hight and Elmquist, Randolph E. and Newell, David B.} } @article { ISI:000446554000001, title = {Failure of Kohn{\textquoteright}s theorem and the apparent failure of the f-sum rule in intrinsic Dirac-Weyl materials in the presence of a filled Fermi sea}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {15}, year = {2018}, month = {OCT 5}, pages = {155112}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.155112}, author = {Throckmorton, Robert E. and S. Das Sarma} } @article { ISI:000439411700003, title = {Ferromagnetism and Wigner crystallization in kagome graphene and related structures}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {3}, year = {2018}, month = {JUL 23}, pages = {035135}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.035135}, author = {Chen, Yuanping and Xu, Shenglong and Xie, Yuee and Zhong, Chengyong and Wu, Congjun and Zhang, S. B.} } @article { ISI:000439974200006, title = {Fingerprints of Berry phases in the bulk exciton spectrum of a topological insulator}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {4}, year = {2018}, month = {JUL 27}, pages = {045430}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.045430}, author = {Allocca, Andrew A. and Efimkin, Dmitry K. and Galitski, Victor M.} } @article { ISI:000433040400001, title = {Floquet Supersymmetry}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {21}, year = {2018}, month = {MAY 24}, pages = {210603}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.210603}, author = {Iadecola, Thomas and Hsieh, Timothy H.} } @article { ISI:000426845500044, title = {Fractal universality in near-threshold magnetic lanthanide dimers}, journal = {SCIENCE ADVANCES}, volume = {4}, number = {2}, year = {2018}, month = {FEB}, pages = {UNSP eaap8308}, issn = {2375-2548}, doi = {10.1126/sciadv.aap8308}, author = {Makrides, Constantinos and Li, Ming and Tiesinga, Eite and Kotochigova, Svetlana} } @article { ISI:000448933900006, title = {Fractional Quantum Hall Effect at nu=2+6/13: The Parton Paradigm for the Second Landau Level}, journal = {PHYSICAL REVIEW LETTERS}, volume = {121}, number = {18}, year = {2018}, month = {NOV 1}, pages = {186601}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.121.186601}, author = {Balram, Ajit C. and Mukherjee, Sutirtha and Park, Kwon and Barkeshli, Maissam and Rudner, Mark S. and Jain, J. K.} } @article {10546, title = {Fractional Quantum Hall Phases of Bosons with Tunable Interactions: From the Laughlin Liquid to a Fractional Wigner Crystal}, journal = {Phys. Rev. Lett.}, volume = {121}, year = {2018}, month = {Dec}, pages = {253403}, doi = {10.1103/PhysRevLett.121.253403}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.121.253403}, author = {Gra{\ss}, Tobias and Bienias, Przemyslaw and Gullans, Michael J. and Lundgren, Rex and Maciejko, Joseph and Gorshkov, Alexey V.} } @article { ISI:000448756700003, title = {Generation of a Lattice of Spin-Orbit Beams via Coherent Averaging}, journal = {PHYSICAL REVIEW LETTERS}, volume = {121}, number = {18}, year = {2018}, month = {OCT 30}, pages = {183602}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.121.183602}, author = {Sarenac, D. and Cory, D. G. and Nsofini, J. and Hincks, I. and Miguel, P. and Arif, M. and Clark, Charles W. and Huber, M. G. and Pushin, D. A.} } @article { ISI:000448973100018, title = {Giant anomalous Nernst effect and quantum-critical scaling in a ferromagnetic semimetal}, journal = {NATURE PHYSICS}, volume = {14}, number = {11}, year = {2018}, month = {NOV}, pages = {1119+}, issn = {1745-2473}, doi = {10.1038/s41567-018-0225-6}, author = {Sakai, Akito and Mizuta, Yo Pierre and Nugroho, Agustinus Agung and Sihombing, Rombang and Koretsune, Takashi and Suzuki, Michi-To and Takemori, Nayuta and Ishii, Rieko and Nishio-Hamane, Daisuke and Arita, Ryotaro and Goswami, Pallab and Nakatsuji, Satoru} } @article { ISI:000441010300002, title = {Global phase diagram and momentum distribution of single-particle excitations in Kondo insulators}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {8}, year = {2018}, month = {AUG 7}, pages = {085110}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.085110}, author = {Pixley, J. H. and Yu, Rong and Paschen, Silke and Si, Qimiao} } @article { ISI:000445057800002, title = {Global Phase Diagram of a Dirty Weyl Liquid and Emergent Superuniversality}, journal = {PHYSICAL REVIEW X}, volume = {8}, number = {3}, year = {2018}, month = {SEP 19}, pages = {031076}, issn = {2160-3308}, doi = {10.1103/PhysRevX.8.031076}, author = {Roy, Bitan and Slager, Robert-Jan and Juricic, Vladimir} } @article {ISI:000428598700001, title = {Hardware-efficient fermionic simulation with a cavity-QED system}, journal = {NPJ QUANTUM INFORMATION}, volume = {4}, year = {2018}, month = {FEB 27}, pages = {16}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {In digital quantum simulation of fermionic models with qubits, non-local maps for encoding are often encountered. Such maps require linear or logarithmic overhead in circuit depth which could render the simulation useless, for a given decoherence time. Here we show how one can use a cavity-QED system to perform digital quantum simulation of fermionic models. In particular, we show that highly nonlocal Jordan-Wigner or Bravyi-Kitaev transformations can be efficiently implemented through a hardware approach. The key idea is using ancilla cavity modes, which are dispersively coupled to a qubit string, to collectively manipulate and measure qubit states. Our scheme reduces the circuit depth in each Trotter step of the Jordan-Wigner encoding by a factor of N-2, comparing to the scheme for a device with only local connectivity, where N is the number of orbitals for a generic two-body Hamiltonian. Additional analysis for the Fermi-Hubbard model on an N x N square lattice results in a similar reduction. We also discuss a detailed implementation of our scheme with superconducting qubits and cavities.}, \%\%Address = {MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND}, issn = {2056-6387}, doi = {10.1038/s41534-018-0065-3}, author = {Zhu, Guanyu and Subasi, Yigit and Whitfield, James D. and Hafezi, Mohammad} } @article { ISI:000443395600003, title = {Helical Majorana edge mode in a superconducting antiferromagnetic quantum spin Hall insulator}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {8}, year = {2018}, month = {AUG 31}, pages = {081412}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.081412}, author = {Huang, Yingyi and Chiu, Ching-Kai} } @article { ISI:000434628400002, title = {Higgs mechanism in higher-rank symmetric U(1) gauge theories}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {23}, year = {2018}, month = {JUN 8}, pages = {235112}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.235112}, author = {Bulmash, Daniel and Barkeshli, Maissam} } @inbook { ISI:000429191300003, title = {High-Dimensional Disorder-Driven Phenomena in Weyl Semimetals, Semiconductors, and Related Systems}, booktitle = {ANNUAL REVIEW OF CONDENSED MATTER PHYSICS, VOL 9}, series = {Annual Review of Condensed Matter Physics}, volume = {9}, year = {2018}, pages = {35-58}, keywords = {Dirac semimetals, disordered systems, localization, phase transitions}, issn = {1947-5454}, doi = {10.1146/annurev-conmatphys-033117-054037}, author = {Syzranov, Sergey V. and Radzihovsky, Leo}, editor = {Sachdev, S and Marchetti, MC} } @article { ISI:000425091300007, title = {High-fidelity quantum gates in Si/SiGe double quantum dots}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {8}, year = {2018}, month = {FEB 15}, pages = {085421}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.085421}, author = {Russ, Maximilian and Zajac, D. M. and Sigillito, A. J. and Borjans, F. and Taylor, J. M. and Petta, J. R. and Burkard, Guido} } @article { ISI:000451992400001, title = {Highly charged ions: Optical clocks and applications in fundamental physics}, journal = {REVIEWS OF MODERN PHYSICS}, volume = {90}, number = {4}, year = {2018}, month = {DEC 4}, pages = {045005}, abstract = {Recent developments in frequency metrology and optical clocks have been based on electronic transitions in atoms and singly charged ions as references. The control over all relevant degrees of freedom in these atoms has enabled relative frequency uncertainties at a level of 10(-18). This accomplishment not only allows for extremely accurate time and frequency measurements, but also to probe our understanding of fundamental physics, such as a possible variation of fundamental constants, a violation of the local Lorentz invariance, and the existence of forces beyond the standard model of physics. In addition, novel clocks are driving the development of sophisticated technical applications. Crucial for applications of clocks in fundamental physics are a high sensitivity to effects beyond the standard model and a small frequency uncertainty of the clock. Highly charged ions offer both. They possess optical transitions which can be extremely narrow and less sensitive to external perturbations compared to current atomic clock species. The large selection of highly charged ions offers narrow transitions that are among the most sensitive ones for the {\textquoteleft}{\textquoteleft}new physics{{\textquoteright}{\textquoteright}} effects. Recent experimental advances in trapping and sympathetic cooling of highly charged ions will in the future enable advanced quantum logic techniques for controlling motional and internal degrees of freedom and thus enable high-accuracy optical spectroscopy. Theoretical progress in calculating the properties of selected highly charged ions has allowed the evaluation of systematic shifts and the prediction of the sensitivity to the physics beyond the standard model. New theoretical challenges and opportunities emerge from relativistic, quantum electrodynamics, and nuclear-size contributions that become comparable with interelectronic correlations. This article reviews the current status of the field, addresses specific electronic configurations and systems which show the most promising properties for research, their potential limitations, and the techniques for their study.}, issn = {0034-6861}, doi = {10.1103/RevModPhys.90.045005}, author = {Kozlov, M. G. and Safronova, M. S. and Lopez-Urrutia, J. R. Crespo and Schmidt, P. O.} } @article { ISI:000425089500005, title = {High-precision measurements and theoretical calculations of indium excited-state polarizabilities}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {2}, year = {2018}, month = {FEB 15}, pages = {022507}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.022507}, author = {Vilas, N. B. and Wang, B. -Y. and Rupasinghe, P. M. and Maser, D. L. and Safronova, M. S. and Safronova, U. I. and Majumder, P. K.} } @article { ISI:000444724300005, title = {Implementing Majorana fermions in a cold-atom honeycomb lattice with textured pairings}, journal = {PHYSICAL REVIEW A}, volume = {98}, number = {3}, year = {2018}, month = {SEP 14}, pages = {033604}, issn = {2469-9926}, doi = {10.1103/PhysRevA.98.033604}, author = {Pan, Ruizhi and Clark, Charles W.} } @article { ISI:000451739700002, title = {Integration of quantum dots with lithium niobate photonics}, journal = {APPLIED PHYSICS LETTERS}, volume = {113}, number = {22}, year = {2018}, month = {NOV 26}, pages = {221102}, abstract = {The integration of quantum emitters with integrated photonics enables complex quantum photonic circuits that are necessary for photonic implementation of quantum simulators, computers, and networks. Thin-film lithium niobate is an ideal material substrate for quantum photonics because it can tightly confine light in small waveguides and has a strong electro-optic effect that can switch and modulate single photons at low power and high speed. However, lithium niobate lacks efficient single-photon emitters, which are essential for scalable quantum photonic circuits. We demonstrate deterministic coupling of single-photon emitters with a lithium niobate photonic chip. The emitters are composed of InAs quantum dots embedded in an InP nanobeam, which we transfer to a lithium niobate waveguide with nanoscale accuracy using a pick-and-place approach. An adiabatic taper transfers single photons emitted into the nanobeam to the lithium niobate waveguide with high efficiency. We verify the single photon nature of the emission using photon correlation measurements performed with an on-chip beamsplitter. Our results demonstrate an important step toward fast, reconfigurable quantum photonic circuits for quantum information processing. Published by AIP Publishing.}, issn = {0003-6951}, doi = {10.1063/1.5054865}, author = {Aghaeimeibodi, Shahriar and Desiatov, Boris and Kim, Je-Hyung and Lee, Chang-Min and Buyukkaya, Mustafa Atabey and Karasahin, Aziz and Richardson, Christopher J. K. and Leavitt, Richard P. and Loncar, Marko and Waks, Edo} } @article { ISI:000447148100013, title = {Long spin-flip time and large Zeeman splitting of holes in type-II ZnTe/ZnSe submonolayer quantum dots}, journal = {JOURNAL OF APPLIED PHYSICS}, volume = {124}, number = {14}, year = {2018}, month = {OCT 14}, pages = {144306}, issn = {0021-8979}, doi = {10.1063/1.5041478}, author = {Ji, H. and Dhomkar, S. and Wu, R. and Ludwig, J. and Lu, Z. and Smirnov, D. and Tamargo, M. C. and Bryant, G. W. and Kuskovsky, I. L.} } @article { ISI:000446561300009, title = {Long-Range Entanglement near a Kondo-Destruction Quantum Critical Point}, journal = {PHYSICAL REVIEW LETTERS}, volume = {121}, number = {14}, year = {2018}, month = {OCT 5}, pages = {147602}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.121.147602}, author = {Wagner, Christopher and Chowdhury, Tathagata and Pixley, J. H. and Ingersent, Kevin} } @article { ISI:000450258700003, title = {Low overhead Clifford gates from joint measurements in surface, color, and hyperbolic codes}, journal = {PHYSICAL REVIEW A}, volume = {98}, number = {5}, year = {2018}, month = {NOV 15}, pages = {052319}, issn = {2469-9926}, doi = {10.1103/PhysRevA.98.052319}, author = {Lavasani, Ali and Barkeshli, Maissam} } @article { ISI:000440590200010, title = {A low-steering piezo-driven mirror}, journal = {REVIEW OF SCIENTIFIC INSTRUMENTS}, volume = {89}, number = {7}, year = {2018}, month = {JUL}, pages = {073110}, issn = {0034-6748}, doi = {10.1063/1.5035326}, author = {Magnan, E. and Maslek, J. and Bracamontes, C. and Restelli, A. and Boulier, T. and Porto, J. V.} } @article { ISI:000442340900001, title = {Machine learning assisted readout of trapped-ion qubits}, journal = {JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS}, volume = {51}, number = {17}, year = {2018}, month = {SEP 14}, pages = {174006}, keywords = {ion traps, machine learning, quantum computing}, issn = {0953-4075}, doi = {10.1088/1361-6455/aad62b}, author = {Seif, Alireza and Landsman, Kevin A. and Linke, Norbert M. and Figgatt, Caroline and Monroe, C. and Hafezi, Mohammad} } @article { ISI:000435336200001, title = {Machine Learning Detection of Bell Nonlocality in Quantum Many-Body Systems}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {24}, year = {2018}, month = {JUN 14}, pages = {240402}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.240402}, author = {Deng, Dong-Ling} } @article { ISI:000452683500004, title = {Machine Learning Many-Body Localization: Search for the Elusive Nonergodic Metal}, journal = {PHYSICAL REVIEW LETTERS}, volume = {121}, number = {24}, year = {2018}, month = {DEC 10}, pages = {245701}, abstract = {The breaking of ergodicity in isolated quantum systems with a single-particle mobility edge is an intriguing subject that has not yet been fully understood. In particular, whether a nonergodic but metallic phase exists or not in the presence of a one-dimensional quasiperiodic potential is currently under active debate. In this Letter, we develop a neural-network-based approach to investigate the existence of this nonergodic metallic phase in a prototype model using many-body entanglement spectra as the sole diagnostic. We find that such a method identifies with high confidence the existence of a nonergodic metallic phase in the midspectrum at an intermediate quasiperiodic potential strength. Our neural-network-based approach shows how supervised machine learning can be applied not only in locating phase boundaries but also in providing a way to definitively examine the existence or not of a novel phase.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.121.245701}, author = {Hsu, Yi-Ting and Li, Xiao and Deng, Dong-Ling and S. Das Sarma} } @article { ISI:000433419500002, title = {Magnon-induced non-Markovian friction of a domain wall in a ferromagnet}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {17}, year = {2018}, month = {MAY 30}, pages = {174433}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.174433}, author = {Kim, Se Kwon and Tchernyshyov, Oleg and Galitski, Victor and Tserkovnyak, Yaroslav} } @article { ISI:000439729800001, title = {Many-body spectral reflection symmetry and protected infinite-temperature degeneracy}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {3}, year = {2018}, month = {JUL 25}, pages = {035139}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.035139}, author = {Schecter, Michael and Iadecola, Thomas} } @article { ISI:000442061000013, title = {Maximally entangled state and Bell{\textquoteright}s inequality in qubits}, journal = {ANNALS OF PHYSICS}, volume = {395}, year = {2018}, month = {AUG}, pages = {183-195}, keywords = {Bell{\textquoteright}s inequality, Maximally entangled state, Topological field theories, Topological states of matter}, issn = {0003-4916}, doi = {10.1016/j.aop.2018.05.016}, author = {Chu, Su-Kuan and Ma, Chen-Te and Miao, Rong-Xin and Wu, Chih-Hung} } @article { ISI:000418495400015, title = {Measurements of enthalpy of sublimation of Ne, N-2, O-2, Ar, CO2, Kr, Xe, and H2O using a double paddle oscillator}, journal = {JOURNAL OF CHEMICAL THERMODYNAMICS}, volume = {118}, year = {2018}, month = {MAR}, pages = {127-138}, keywords = {Argon, Carbon dioxide, Double paddle oscillator, Enthalpy of sublimation, Krypton, Neon, Nitrogen, Oxygen, Xenon and water}, issn = {0021-9614}, doi = {10.1016/j.jct.2017.11.004}, author = {Shakeel, Hamza and Wei, Haoyan and Pomeroy, J. M.} } @article { ISI:000428982800001, title = {Measuring nuclear-spin-dependent parity violation with molecules: Experimental methods and analysis of systematic errors}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {4}, year = {2018}, month = {APR 3}, pages = {042101}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.042101}, author = {Altuntas, Emine and Ammon, Jeffrey and Cahn, Sidney B. and DeMille, David} } @article { ISI:000418043100001, title = {Measuring the dielectric and optical response of millimeter-scale amorphous and hexagonal boron nitride films grown on epitaxial graphene}, journal = {2D MATERIALS}, volume = {5}, number = {1}, year = {2018}, month = {JAN}, pages = {011011}, keywords = {amorphous boron nitride, epitaxial graphene, hexagonal boron nitride, optical dielectric functions}, issn = {2053-1583}, doi = {10.1088/2053-1583/aa9ea3}, author = {Rigosi, Albert F. and Hill, Heather M. and Glavin, Nicholas R. and Pookpanratana, Sujitra J. and Yang, Yanfei and Boosalis, Alexander G. and Hu, Jiuning and Rice, Anthony and Allerman, Andrew A. and Nguyen, Nhan V. and Hacker, Christina A. and Elmquist, Randolph E. and Walker, Angela R. Hight and Newell, David B.} } @article { ISI:000451329500012, title = {Measuring the Renyi entropy of a two-site Fermi-Hubbard model on a trapped ion quantum computer}, journal = {PHYSICAL REVIEW A}, volume = {98}, number = {5}, year = {2018}, month = {NOV 26}, pages = {052334}, abstract = {The efficient simulation of correlated quantum systems is a promising near-term application of quantum computers. Here, we present a measurement of the second Renyi entropy of the ground state of the two-site Fermi-Hubbard model on a five-qubit programmable quantum computer based on trapped ions. Our work illustrates the extraction of a nonlinear characteristic of a quantum state using a controlled-swap gate acting on two copies of the state. This scalable measurement of entanglement on a universal quantum computer will, with more qubits, provide insights into many-body quantum systems that are impossible to simulate on classical computers.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.98.052334}, author = {Linke, N. M. and Johri, S. and Figgatt, C. and Landsman, K. A. and Matsuura, A. Y. and Monroe, C.} } @article { ISI:000447297200006, title = {Metamorphosis of Andreev bound states into Majorana bound states in pristine nanowires}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {14}, year = {2018}, month = {OCT 15}, pages = {144511}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.144511}, author = {Huang, Yingyi and Pan, Haining and Liu, Chun-Xiao and Sau, Jay D. and Stanescu, Tudor D. and S. Das Sarma} } @article { ISI:000447077700007, title = {Methods for preparation and detection of neutron spin-orbit states}, journal = {NEW JOURNAL OF PHYSICS}, volume = {20}, year = {2018}, month = {OCT 10}, pages = {103012}, keywords = {neutron optics, orbital angular momentum, spin-orbit states}, issn = {1367-2630}, doi = {10.1088/1367-2630/aae3ac}, author = {Sarenac, D. and Nsofini, J. and Hincks, I. and Arif, M. and Clark, Charles W. and Cory, D. G. and Huber, M. G. and Pushin, D. A.} } @article { ISI:000445503000001, title = {Microwave-activated controlled-Z gate for fixed-frequency fluxonium qubits}, journal = {PHYSICAL REVIEW A}, volume = {98}, number = {3}, year = {2018}, month = {SEP 24}, pages = {030301}, issn = {2469-9926}, doi = {10.1103/PhysRevA.98.030301}, author = {Nesterov, Konstantin N. and Pechenezhskiy, V, Ivan and Wang, Chen and Manucharyan, Vladimir E. and Vavilov, Maxim G.} } @article { ISI:000425707400027, title = {A model for metastable magnetism in the hidden-order phase of URu2Si2}, journal = {ANNALS OF PHYSICS}, volume = {388}, year = {2018}, month = {JAN}, pages = {398-407}, keywords = {Ginzburg-Landau theory, Heavy fermion, Hidden order, Kerr effect}, issn = {0003-4916}, doi = {10.1016/j.aop.2017.11.024}, author = {Boyer, Lance and Yakovenko, Victor M.} } @conference { ISI:000455155000090, title = {Multiplexing: Moving Real-World Single-Photon Sources toward the Ideal}, booktitle = {2018 IEEE PHOTONICS SOCIETY SUMMER TOPICAL MEETING SERIES (SUM)}, year = {2018}, note = {IEEE Photonics Society Summer Topical Meeting Series (SUM), Waikoloa Village, HI, JUL 09-11, 2018}, pages = {199}, isbn = {978-1-5386-5343-2}, author = {Migdall, Alan} } @article { ISI:000424507800014, title = {Multipolar Polarizabilities and Hyperpolarizabilities in the Sr Optical Lattice Clock}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {6}, year = {2018}, month = {FEB 8}, pages = {063204}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.063204}, author = {Porsev, S. G. and Safronova, M. S. and Safronova, U. I. and Kozlov, M. G.} } @article { ISI:000445109300001, title = {On the need for soft dressing}, journal = {JOURNAL OF HIGH ENERGY PHYSICS}, number = {9}, year = {2018}, month = {SEP 20}, pages = {121}, keywords = {Effective Field Theories, Gauge Symmetry, Scattering Amplitudes, Space-Time Symmetries}, issn = {1029-8479}, doi = {10.1007/JHEP09(2018)121}, author = {Carney, Daniel and Chaurette, Laurent and Neuenfeld, Dominik and Semenoff, Gordon} } @article { ISI:000427007200003, title = {New Methods for Testing Lorentz Invariance with Atomic Systems}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {10}, year = {2018}, month = {MAR 8}, pages = {103202}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.103202}, author = {Shaniv, R. and Ozeri, R. and Safronova, M. S. and Porsev, S. G. and Dzuba, V. A. and flambaum, v. v. and Haffner, H.} } @conference { ISI:000450231900351, title = {NIST Kibble balance performance}, booktitle = {2018 CONFERENCE ON PRECISION ELECTROMAGNETIC MEASUREMENTS (CPEM 2018)}, year = {2018}, note = {Conference on Precision Electromagnetic Measurements (CPEM), Paris, FRANCE, JUL 08-13, 2018}, keywords = {Kibble balance, mass metrology, Planck constant, redefinition of the SI}, isbn = {978-1-5386-0974-3}, author = {Seifert, F. and Haddad, D. and Chao, L. S. and Newell, D. B. and Pratt, J. R. and Williams, C. and Schlamminger, S.} } @article { ISI:000451329500021, title = {Nobelium energy levels and hyperfine-structure constants}, journal = {PHYSICAL REVIEW A}, volume = {98}, number = {5}, year = {2018}, month = {NOV 26}, pages = {052512}, abstract = {Advances in laser spectroscopy of superheavy (Z > 100) elements enabled determination of the nuclear moments of the heaviest nuclear which required high-precision atomic calculations of the relevant hyperfine-structure (hfs) constants. Here, we calculated the hfs constants and energy levels for a number of nobelium (Z = 102) states using a hybrid approach combining linearized coupled-cluster and configuration interaction methods. We also carried out an extensive study of the No energies using the 16-electro configuration interaction method to determine the position of the 5f(13)7s(2)6d and 5f(13)7s(2)7p levels with a hole in the 5 f shell to evaluate their potential effect on the hyperfine-structure calculations of the low-lying 5f(14)7s6d and 5f(14)7s7p levels. We find that unlike the case of Yb, the mixing of the low-lying levels with filled and unfilled f shells is small and does not significantly influence their properties. The resulting hfs constants for the 5f(14)7s7p P-1(1)0 level, combined with laser-spectroscopy measurement, were used to extract nobelium nuclear properties.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.98.052512}, author = {Porsev, S. G. and Safronova, M. S. and Safronova, I, U. and Dzuba, V. A. and flambaum, v. v.} } @article { ISI:000450139700007, title = {Nonlinear sigma model approach to many-body quantum chaos: Regularized and unregularized out-of-time-ordered correlators}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {20}, year = {2018}, month = {NOV 14}, pages = {205124}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.205124}, author = {Liao, Yunxiang and Galitski, Victor} } @article { ISI:000451010600006, title = {Nuclear Charge Radii of Th-229 from Isotope and Isomer Shifts}, journal = {PHYSICAL REVIEW LETTERS}, volume = {121}, number = {21}, year = {2018}, month = {NOV 21}, pages = {213001}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.121.213001}, author = {Safronova, M. S. and Porsev, S. G. and Kozlov, M. G. and Thielking, J. and Okhapkin, M. V. and Glowacki, P. and Meier, D. M. and Peik, E.} } @article { ISI:000450584900008, title = {Observation of bound state self-interaction in a nano-eV atom collider}, journal = {NATURE COMMUNICATIONS}, volume = {9}, year = {2018}, month = {NOV 20}, pages = {4895}, issn = {2041-1723}, doi = {10.1038/s41467-018-07375-8}, author = {Thomas, Ryan and Chilcott, Matthew and Tiesinga, Eite and Deb, Amita B. and Kjaergaard, Niels} } @article {ISI:000424750200005, title = {Observation of Hopping and Blockade of Bosons in a Trapped Ion Spin Chain}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {7}, year = {2018}, month = {FEB 12}, pages = {073001}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The local phonon modes in a Coulomb crystal of trapped ions can represent a Hubbard system of coupled bosons. We selectively prepare single excitations at each site and observe free hopping of a boson between sites, mediated by the long-range Coulomb interaction between ions. We then implement phonon blockades on targeted sites by driving a Jaynes-Cummings interaction on individually \%\%Addressed ions to couple their internal spin to the local phonon mode. The resulting dressed states have energy splittings that can be tuned to suppress phonon hopping into the site. This new experimental approach opens up the possibility of realizing large-scale Hubbard systems from the bottom up with tunable interactions at the single-site level.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.073001}, author = {Debnath, S. and Linke, N. M. and Wang, S. -T. and Figgatt, C. and Landsman, K. A. and Duan, L. -M. and Monroe, C.} } @article {ISI:000425116200042, title = {Observation of three-photon bound states in a quantum nonlinear medium}, journal = {SCIENCE}, volume = {359}, number = {6377}, year = {2018}, month = {FEB 16}, pages = {783-786}, publisher = {AMER ASSOC ADVANCEMENT SCIENCE}, type = {Article}, abstract = {Bound states of massive particles, such as nuclei, atoms, or molecules, constitute the bulk of the visible world around us. By contrast, photons typically only interact weakly. We report the observation of traveling three-photon bound states in a quantum nonlinear medium where the interactions between photons are mediated by atomic Rydberg states. Photon correlation and conditional phase measurements reveal the distinct bunching and phase features associated with three-photon and two-photon bound states. Such photonic trimers and dimers possess shape-preserving wave functions that depend on the constituent photon number. The observed bunching and strongly nonlinear optical phase are described by an effective field theory of Rydberg-induced photon-photon interactions. These observations demonstrate the ability to realize and control strongly interacting quantum many-body states of light.}, \%Address = {1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA}, issn = {0036-8075}, doi = {10.1126/science.aao7293}, author = {Liang, Qi-Yu and Venkatramani, Aditya V. and Cantu, Sergio H. and Nicholson, Travis L. and Gullans, Michael J. and Gorshkov, Alexey V. and Thompson, Jeff D. and Chin, Cheng and Lukin, Mikhail D. and Vuletic, Vladan} } @article { ISI:000447918000006, title = {Odd-frequency pairing in the edge states of superconducting pnictides in the coexistence phase with antiferromagnetism}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {14}, year = {2018}, month = {OCT 22}, pages = {144517}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.144517}, author = {Youmans, Cody and Ghazaryan, Areg and Kargarian, Mehdi and Ghaemi, Pouyan} } @article { ISI:000447301700001, title = {Optical control over bulk excitations in fractional quantum Hall systems}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {15}, year = {2018}, month = {OCT 15}, pages = {155124}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.155124}, author = {Grass, Tobias and Gullans, Michael and Bienias, Przemyslaw and Zhu, Guanyu and Ghazaryan, Areg and Ghaemi, Pouyan and Hafezi, Mohammad} } @article { ISI:000445733100006, title = {Optical Lattice with Torus Topology}, journal = {PHYSICAL REVIEW LETTERS}, volume = {121}, number = {13}, year = {2018}, month = {SEP 26}, pages = {133002}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.121.133002}, author = {Kim, Hwanmun and Zhu, Guanyu and Porto, V, J. and Hafezi, Mohammad} } @article {ISI:000430543700006, title = {Optimal and secure measurement protocols for quantum sensor networks}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {4}, year = {2018}, month = {APR 23}, pages = {042337}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Studies of quantum metrology have shown that the use of many-body entangled states can lead to an enhancement in sensitivity when compared with unentangled states. In this paper, we quantify the metrological advantage of entanglement in a setting where the measured quantity is a linear function of parameters individually coupled to each qubit. We first generalize the Heisenberg limit to the measurement of nonlocal observables in a quantum network, deriving a bound based on the multiparameter quantum Fisher information. We then propose measurement protocols that can make use of Greenberger-Horne-Zeilinger (GHZ) states or spin-squeezed states and show that in the case of GHZ states the protocol is optimal, i.e., it saturates our bound. We also identify nanoscale magnetic resonance imaging as a promising setting for this technology.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.042337}, author = {Eldredge, Zachary and Foss-Feig, Michael and Gross, Jonathan A. and Rolston, S. L. and Gorshkov, Alexey V.} } @article { ISI:000443327900004, title = {Optimization of photon storage fidelity in ordered atomic arrays}, journal = {NEW JOURNAL OF PHYSICS}, volume = {20}, year = {2018}, month = {AUG 31}, pages = {083048}, keywords = {atomic ensembles, quantum memory, subradiance, superradiance}, issn = {1367-2630}, doi = {10.1088/1367-2630/aadb74}, author = {Manzoni, M. T. and Moreno-Cardoner, M. and Asenjo-Garcia, A. and Porto, J. V. and Gorshkov, A. V. and Chang, D. E.} } @article { ISI:000419549600036, title = {Optimized phase sensing in a truncated SU(1,1) interferometer}, journal = {OPTICS EXPRESS}, volume = {26}, number = {1}, year = {2018}, month = {JAN 8}, pages = {391-401}, issn = {1094-4087}, doi = {10.1364/OE.26.000391}, author = {Gupta, Prasoon and Schmittberger, Bonnie L. and Anderson, Brian E. and Jones, Kevin M. and Lett, Paul D.} } @article {ISI:000428647300012, title = {Optomechanical approach to controlling the temperature and chemical potential of light}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {3}, year = {2018}, month = {MAR 29}, pages = {033850}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Massless particles, including photons, are not governed by particle conservation law during their typical interaction with matter even at low energies and thus have no chemical potential. However, in driven systems, near-equilibrium dynamics can lead to equilibration of photons with a finite number, describable using an effective chemical potential {[}M. Hafezi et al., Phys. Rev. B 92, 174305 (2015)]. Here we build upon this general concept with an implementation appropriate for a photon-based quantum simulator. We consider how laser cooling of a well-isolated mechanical mode can provide an effective low-frequency bath for the quantum simulator system. We show that the use of auxiliary photon modes, coupled by the mechanical system, enables control of both the chemical potential and temperature of the resulting photonic quantum simulator{\textquoteright}s grand canonical ensemble.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.033850}, author = {Wang, Chiao-Hsuan and Taylor, Jacob M.} } @article { ISI:000433905200011, title = {Orbital quantum magnetism in spin dynamics of strongly interacting magnetic lanthanide atoms}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {5}, year = {2018}, month = {MAY 31}, pages = {053627}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.053627}, author = {Li, Ming and Tiesinga, Eite and Kotochigova, Svetlana} } @article {ISI:000430909100001, title = {Out-of-time-order correlators in finite open systems}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {16}, year = {2018}, month = {APR 26}, pages = {161114}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study out-of-time-order correlators (OTOCs) of the form <(A) over cap (t) (B) over cap (0) (C) over cap (t) (D) over cap (0)> for a quantum system weakly coupled to a dissipative environment. Such an open system may serve as a model of, e. g., a small region in a disordered interacting medium coupled to the rest of this medium considered as an environment. We demonstrate that for a system with discrete energy levels the OTOC saturates exponentially alpha Sigma a(i)e(-t/tau i) + const to a constant value at t -> infinity, in contrast with quantum-chaotic systemswhich exhibit exponential growth of OTOCs. Focusing on the case of a two-level system, we calculate microscopically the decay times tau(i) and the value of the saturation constant. Because some OTOCs are immune to dephasing processes and some are not, such correlators may decay on two sets of parametrically different time scales related to inelastic transitions between the system levels and to pure dephasing processes, respectively. In the case of a classical environment, the evolution of the OTOC can be mapped onto the evolution of the density matrix of two systems coupled to the same dissipative environment.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.161114}, author = {Syzranov, S. V. and Gorshkov, A. V. and Galitski, V.} } @article { ISI:000439057800004, title = {Parton construction of a wave function in the anti-Pfaffian phase}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {3}, year = {2018}, month = {JUL 18}, pages = {035127}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.035127}, author = {Balram, Ajit C. and Barkeshli, Maissam and Rudner, Mark S.} } @article { ISI:000436968900002, title = {Perpetual emulation threshold of PT-symmetric Hamiltonians}, journal = {JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL}, volume = {51}, number = {32}, year = {2018}, month = {AUG 10}, pages = {325302}, keywords = {non-Hermitian, pseudospins, PT-symmetry}, issn = {1751-8113}, doi = {10.1088/1751-8121/aacc5e}, author = {Trypogeorgos, D. and Valdes-Curiell, A. and Ian B Spielman and Emary, C.} } @article { ISI:000443395300001, title = {Phonon-induced Majorana qubit relaxation in tunnel-coupled two-island topological superconductors}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {7}, year = {2018}, month = {AUG 31}, pages = {075159}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.075159}, author = {Song, Yang and S. Das Sarma} } @article {ISI:000427318600005, title = {Photon Subtraction by Many-Body Decoherence}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {11}, year = {2018}, month = {MAR 13}, pages = {113601}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We experimentally and theoretically investigate the scattering of a photonic quantum field from another stored in a strongly interacting atomic Rydberg ensemble. Considering the many-body limit of this problem, we derive an exact solution to the scattering-induced spatial decoherence of multiple stored photons, allowing for a rigorous understanding of the underlying dissipative quantum dynamics. Combined with our experiments, this analysis reveals a correlated coherence-protection process in which the scattering from one excitation can shield all others from spatial decoherence. We discuss how this effect can be used to manipulate light at the quantum level, providing a robust mechanism for single-photon subtraction, and experimentally demonstrate this capability.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.113601}, author = {Murray, C. R. and Mirgorodskiy, I. and Tresp, C. and Braun, C. and Paris-Mandoki, A. and Gorshkov, A. V. and Hofferberth, S. and Pohl, T.} } @article { ISI:000439279500007, title = {Photon thermalization via laser cooling of atoms}, journal = {PHYSICAL REVIEW A}, volume = {98}, number = {1}, year = {2018}, month = {JUL 19}, pages = {013834}, issn = {2469-9926}, doi = {10.1103/PhysRevA.98.013834}, author = {Wang, Chiao-Hsuan and Gullans, M. J. and Porto, J. V. and Phillips, William D. and Taylor, Jacob M.} } @article { ISI:000442483400036, title = {Photonic topological Anderson insulators}, journal = {NATURE}, volume = {560}, number = {7719}, year = {2018}, month = {AUG 23}, pages = {461+}, issn = {0028-0836}, doi = {10.1038/s41586-018-0418-2}, author = {Stutzer, Simon and Plotnik, Yonatan and Lumer, Yaakov and Titum, Paraj and Lindner, Netanel H. and Segev, Mordechai and Rechtsman, Mikael C. and Szameit, Alexander} } @article { ISI:000451606600001, title = {Plasmon-pole approximation for many-body effects in extrinsic graphene}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {19}, year = {2018}, month = {NOV 28}, pages = {195140}, abstract = {We develop the plasmon-pole approximation (PPA) theory for calculating the carrier self-energy of extrinsic graphene as a function of doping density within analytical approximations to the GW random phase approximation (GW-RPA). Our calculated self-energy shows excellent quantitative agreement with the corresponding full GW-RPA calculation results in spite of the simplicity of the PPA, establishing the general validity of the plasmon-pole approximation scheme. We also provide a comparison between the PPA and the hydrodynamic approximation in graphene, and comment on the experimental implications of our findings.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.195140}, author = {Hwang, E. H. and Throckmorton, Robert E. and S. Das Sarma} } @article { ISI:000452612200037, title = {A post-processing-free single-photon random number generator with ultra-low latency}, journal = {OPTICS EXPRESS}, volume = {26}, number = {25}, year = {2018}, month = {DEC 10}, pages = {32788-32801}, abstract = {The low-latency requirements of a practical loophole-free Bell test preclude time-consuming post-processing steps that are often used to improve the statistical quality of a physical random number generator (RNG). Here we demonstrate a post-processing-free RNG that produces a random bit within 2.4(2) ns of an input trigger. We use weak feedback to eliminate long-term drift, resulting in 24 hour operation with output that is statistically indistinguishable from a Bernoulli process. We quantify the impact of the feedback on the predictability of the output as less than 6.4x10(-7) and demonstrate the utility of the Allan variance as a tool for characterizing non-idealities in RNGs. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement}, issn = {1094-4087}, doi = {10.1364/OE.26.032788}, author = {Wayne, Michael A. and Migdall, Alan L. and Levine, Zachary H. and Bienfang, Joshua C.} } @article {ISI:000423393300009, title = {Probe Knots and Hopf Insulators with Ultracold Atoms}, journal = {CHINESE PHYSICS LETTERS}, volume = {35}, number = {1}, year = {2018}, month = {JAN}, pages = {013701}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {Knots and links are fascinating and intricate topological objects. Their influence spans from DNA and molecular chemistry to vortices in superfluid helium, defects in liquid crystals and cosmic strings in the early universe. Here we find that knotted structures also exist in a peculiar class of three-dimensional topological insulators-the Hopf insulators. In particular, we demonstrate that the momentum-space spin textures of Hopf insulators are twisted in a nontrivial way, which implies the presence of various knot and link structures. We further illustrate that the knots and nontrivial spin textures can be probed via standard time-of-flight images in cold atoms as preimage contours of spin orientations in stereographic coordinates. The extracted Hopf invariants, knots, and links are validated to be robust to typical experimental imperfections. Our work establishes the existence of knotted structures in Hopf insulators, which may have potential applications in spintronics and quantum information processing.}, \%\%Address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}, issn = {0256-307X}, doi = {10.1088/0256-307X/35/1/013701}, author = {Deng, Dong-Ling and Wang, Sheng-Tao and Sun, Kai and Duan, L. -M.} } @article {ISI:000423115200014, title = {Probing electron-phonon interactions in the charge-photon dynamics of cavity-coupled double quantum dots}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {3}, year = {2018}, month = {JAN 16}, pages = {035305}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Electron-phonon coupling is known to play an important role in the charge dynamics of semiconductor quantum dots. Here we explore its role in the combined charge-photon dynamics of cavity-coupled double quantum dots. Previous work on these systems has shown that strong electron-phonon coupling leads to a large contribution to photoemission and gain from phonon-assisted emission and absorption processes. We compare the effects of this phonon sideband in three commonly investigated gate-defined quantum dot material systems: InAs nanowires and GaAs and Si two-dimensional electron gases (2DEGs). We compare our theory with existing experimental data from cavity-coupled InAs nanowire and GaAs 2DEG double quantum dots and find quantitative agreement only when the phonon sideband and photoemission processes during lead tunneling are taken into account. Finally, we show that the phonon sideband also leads to a sizable renormalization of the cavity frequency, which allows for direct spectroscopic probes of the electron-phonon coupling in these systems.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.035305}, author = {Gullans, M. J. and Taylor, J. M. and Petta, J. R.} } @article { ISI:000434633000006, title = {Probing Sizes and Shapes of Nobelium Isotopes by Laser Spectroscopy}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {23}, year = {2018}, month = {JUN 8}, pages = {232503}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.232503}, author = {Raeder, S. and Ackermann, D. and Backe, H. and Beerwerth, R. and Berengut, J. C. and Block, M. and Borschevsky, A. and Cheal, B. and Chhetri, P. and Duellmann, Ch. E. and Dzuba, V. A. and Eliav, E. and Even, J. and Ferrer, R. and flambaum, v. v. and Fritzsche, S. and Giacoppo, F. and Goetz, S. and Hessberger, F. P. and Huyse, M. and Kaldor, U. and Kaleja, O. and Khuyagbaatar, J. and Kunz, P. and Laatiaoui, M. and Lautenschlager, F. and Lauth, W. and Mistry, A. K. and Ramirez, E. Minaya and Nazarewicz, W. and Porsev, S. G. and Safronova, M. S. and Safronova, U. I. and Schuetrumpf, B. and Van Duppen, P. and Walther, T. and Wraith, C. and Yakushev, A.} } @article { ISI:000447638200072, title = {QFlow lite dataset: A machine-learning approach to the charge states in quantum dot experiments}, journal = {PLOS ONE}, volume = {13}, number = {10}, year = {2018}, month = {OCT 17}, pages = {e0205844}, issn = {1932-6203}, doi = {10.1371/journal.pone.0205844}, author = {Zwolak, Justyna P. and Kalantre, Sandesh S. and Wu, Xingyao and Ragole, Stephen and Taylor, Jacob M.} } @article {9191, title = {Quantized Majorana conductance}, journal = {Nature}, volume = {Advanced Online Publication}, year = {2018}, month = {03/2018}, url = {http://dx.doi.org/10.1038/nature26142}, author = {Zhang, Hao and Liu, Chun-Xiao and Gazibegovic, Sasa and Xu, Di and Logan, John A. and Wang, Guanzhong and van Loo, Nick and Bommer, Jouri D. S. and de Moor, Michiel W. A. and Car, Diana and Op het Veld, Roy L. M. and van Veldhoven, Petrus J. and Koelling, Sebastian and Verheijen, Marcel A. and Pendharkar, Mihir and Pennachio, Daniel J. and Shojaei, Borzoyeh and Lee, Joon Sue and Palmstr{\o}m, Chris J. and Bakkers, Erik P. A. M. and S. Das Sarma and Kouwenhoven, Leo P.} } @article { ISI:000449780400004, title = {Quantum field theory for the chiral clock transition in one spatial dimension}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {20}, year = {2018}, month = {NOV 9}, pages = {205118}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.205118}, author = {Whitsitt, Seth and Samajdar, Rhine and Sachdev, Subir} } @article { ISI:000450242200180, title = {Quantum Hall device data monitoring following encapsulating polymer deposition}, journal = {DATA IN BRIEF}, volume = {20}, year = {2018}, month = {OCT}, pages = {1201-1208}, issn = {2352-3409}, doi = {10.1016/j.dib.2018.08.121}, author = {Rigosi, Albert F. and Liu, Chieh-I and Wu, Bi Yi and Lee, Hsin-Yen and Kruskopf, Mattias and Yang, Yanfei and Hill, Heather M. and Hu, Jiuning and Bittle, Emily G. and Obrzut, Jan and Walker, Angela R. Hight and Elmquist, Randolph E. and Newell, David B.} } @article { ISI:000447918000003, title = {Quantum inverse freezing and mirror-glass order}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {14}, year = {2018}, month = {OCT 22}, pages = {144204}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.144204}, author = {Iadecola, Thomas and Schecter, Michael} } @article { ISI:000428145500001, title = {Quantum receiver for large alphabet communication}, journal = {OPTICA}, volume = {5}, number = {3}, year = {2018}, month = {MAR 20}, pages = {227-232}, issn = {2334-2536}, doi = {10.1364/OPTICA.5.000227}, author = {Burenkov, I. A. and Tikhonova, O. V. and Polyakov, S. V.} } @article { ISI:000436275400032, title = {Quantum Thermodynamics at Strong Coupling: Operator Thermodynamic Functions and Relations}, journal = {ENTROPY}, volume = {20}, number = {6}, year = {2018}, month = {JUN}, pages = {423}, keywords = {operator thermodynamic functions, quantum thermodynamics, strong coupling}, issn = {1099-4300}, doi = {10.3390/e20060423}, author = {Hsiang, Jen-Tsung and Hu, Bei-Lok} } @article { ISI:000423237900002, title = {Quantum thermodynamics from the nonequilibrium dynamics of open systems: Energy, heat capacity, and the third law}, journal = {PHYSICAL REVIEW E}, volume = {97}, number = {1}, year = {2018}, month = {JAN 23}, pages = {012135}, issn = {2470-0045}, doi = {10.1103/PhysRevE.97.012135}, author = {Hsiang, J. -T. and Chou, C. H. and Subasi, Y. and Hu, B. L.} } @article { ISI:000438348200004, title = {Quantum transport in graphene p-n junctions with moire superlattice modulation}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {4}, year = {2018}, month = {JUL 12}, pages = {045412}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.045412}, author = {Hu, Jiuning and Rigosi, Albert F. and Lee, Ji U. and Lee, Hsin-Yen and Yang, Yanfei and Liu, I, Chieh- and Elmquist, Randolph E. and Newell, David B.} } @article { ISI:000454161400003, title = {Quasiparticle gaps in multiprobe Majorana nanowires}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {22}, year = {2018}, month = {DEC 18}, pages = {224512}, abstract = {We theoretically study a spin-orbit-coupled nanowire proximitized by a superconductor in the presence of an externally applied Zeeman field ({{\textquoteright}{\textquoteright}}Majorana nanowire{{\textquoteright}{\textquoteright}}) with zero-energy Majorana bound states localized at the two ends of the wire when the Zeeman spin splitting is large enough for the system to enter the topological phase. The specific physics of interest in the current work is the effect of having several tunnel probes attached to the wire along its length. Such tunnel probes should allow, as a matter of principle, one to observe both the predicted bulk superconducting gap closing and opening associated with the topological quantum phase transition as well as the Majorana bound states at the wire ends showing up as zero-bias conductance peaks, depending on which probes are used for the tunneling spectroscopy measurement. Because of the possible invasive nature of the tunnel probes, producing local potential fluctuations in the nanowire, we find the physical situation to be quite complex. In particular, depending on the details of the tunnel barrier operational at the probes, the Majorana nanowire could manifest additional low-energy Andreev bound states which will manifest their own almost-zero-bias peaks, complicating the interpretation of the tunneling data in multiprobe Majorana nanowires. We use two complementary microscopic models to simulate the probes, finding that the tunneling conductance spectrum depends rather sensitively on the details of the tunnel barriers at the probes, but in some situations it should be possible to observe the Majorana bound-state-induced zero-bias conductance peak at the wire ends along with the gap closing and opening features associated with the bulk topological quantum phase transition in the multiprobe Majorana nanowires. Our detailed numerical results indicate that such a system should also be capable of directly manifesting the nonlocal conductance correlations arising from Majorana bound states at the two ends of the nanowire. We apply our general analysis to simulate a recent multiprobe nanowire experiment commenting on the nature of the quasiparticle gaps likely controlling the experimental observations.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.224512}, author = {Huang, Yingyi and Sau, Jay D. and Stanescu, Tudor D. and S. Das Sarma} } @article { ISI:000443584000010, title = {Quo vadis now, cold molecules?}, journal = {NATURE PHYSICS}, volume = {14}, number = {9}, year = {2018}, month = {SEP}, pages = {873-874}, issn = {1745-2473}, doi = {10.1038/s41567-018-0260-3}, author = {Julienne, Paul S.} } @article { ISI:000445322300004, title = {Radiative Enhancement of Single Quantum Emitters in WSe2 Monolayers Using Site-Controlled Metallic Nanopillars}, journal = {ACS PHOTONICS}, volume = {5}, number = {9}, year = {2018}, month = {SEP}, pages = {3466-3471}, keywords = {plasmonic nanopillars, quantum emitters, single-defect emitters, transition-metal dichalcogenide, two-dimensional semiconductors, WSe2}, issn = {2330-4022}, doi = {10.1021/acsphotonics.8b00580}, author = {Cai, Tao and Kim, Je-Hyung and Yang, Zhili and Dutta, Subhojit and Aghaeimeibodi, Shahriar and Waks, Edo} } @article {9246, title = {A Rapidly Expanding Bose-Einstein Condensate: An Expanding Universe in the Lab}, journal = {Phys. Rev. X}, volume = {8}, year = {2018}, month = {Apr}, pages = {021021}, doi = {10.1103/PhysRevX.8.021021}, url = {https://link.aps.org/doi/10.1103/PhysRevX.8.021021}, author = {Eckel, S and Kumar, A and Jacobson, T and Ian B Spielman and Campbell, G K} } @article { ISI:000437838000009, title = {Reconfigurable Topological Phases in Next-Nearest-Neighbor Coupled Resonator Lattices}, journal = {PHYSICAL REVIEW LETTERS}, volume = {121}, number = {2}, year = {2018}, month = {JUL 9}, pages = {023901}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.121.023901}, author = {Leykam, Daniel and Mittal, S. and Hafezi, M. and Chong, Y. D.} } @article { ISI:000419097100004, title = {Relativistic all-order many-body calculation of energies, wavelengths, and M1 and E2 transition rates for the 3d(n) configurations in tungsten ions}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {1}, year = {2018}, month = {JAN 3}, pages = {012502}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.012502}, author = {Safronova, M. S. and Safronova, U. I. and Porsev, S. G. and Kozlov, M. G. and Ralchenko, Yu.} } @article { ISI:000423283200042, title = {Resonantly driven CNOT gate for electron spins}, journal = {SCIENCE}, volume = {359}, number = {6374}, year = {2018}, month = {JAN 26}, pages = {439-442}, issn = {0036-8075}, doi = {10.1126/science.aao5965}, author = {Zajac, D. M. and Sigillito, A. J. and Russ, M. and Borjans, F. and Taylor, J. M. and Burkard, G. and Petta, J. R.} } @article { ISI:000419619800001, title = {Robust 2-Qubit Gates in a Linear Ion Crystal Using a Frequency-Modulated Driving Force}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {2}, year = {2018}, month = {JAN 9}, pages = {020501}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.020501}, author = {Leung, Pak Hong and Landsman, Kevin A. and Figgatt, Caroline and Linke, Norbert M. and Monroe, Christopher and Brown, Kenneth R.} } @conference { ISI:000455155000056, title = {Scalable quantum photonics using quantum dots}, booktitle = {2018 IEEE PHOTONICS SOCIETY SUMMER TOPICAL MEETING SERIES (SUM)}, year = {2018}, note = {IEEE Photonics Society Summer Topical Meeting Series (SUM), Waikoloa Village, HI, JUL 09-11, 2018}, pages = {129-130}, isbn = {978-1-5386-5343-2}, author = {Waks, Edo and Sun, Shuo and Kim, Jehyung and Richardson, Christopher and Leavitt, Richard and Solomon, Glenn} } @article { ISI:000436944600001, title = {Search for new physics with atoms and molecules}, journal = {REVIEWS OF MODERN PHYSICS}, volume = {90}, number = {2}, year = {2018}, month = {JUN 29}, pages = {025008}, issn = {0034-6861}, doi = {10.1103/RevModPhys.90.025008}, author = {Safronova, M. S. and Budker, D. and DeMille, D. and Kimball, Derek F. Jackson and Derevianko, A. and Clark, Charles W.} } @article {10056, title = {Second Chern number of a quantum-simulated non-Abelian Yang monopole}, journal = {Science}, volume = {360}, year = {2018}, pages = {1429{\textendash}1434}, abstract = {Topological properties of physical systems are reflected in so-called Chern numbers: A nonzero Chern number typically means that a system is topologically nontrivial. Sugawa et al. engineered a cold atom system with a nonzero second Chern number, in contrast to condensed matter physics, where only the first Chern number is usually invoked. The exotic topology relates to the emergence of a type of magnetic monopole called the Yang monopole (known from theoretical high-energy physics) in a five-dimensional space of internal degrees of freedom in a rubidium Bose-Einstein condensate. The results illustrate the potential of cold atoms physics to simulate high-energy phenomena.Science, this issue p. 1429Topological order is often quantified in terms of Chern numbers, each of which classifies a topological singularity. Here, inspired by concepts from high-energy physics, we use quantum simulation based on the spin degrees of freedom of atomic Bose-Einstein condensates to characterize a singularity present in five-dimensional non-Abelian gauge theories{\textemdash}a Yang monopole. We quantify the monopole in terms of Chern numbers measured on enclosing manifolds: Whereas the well-known first Chern number vanishes, the second Chern number does not. By displacing the manifold, we induce and observe a topological transition, where the topology of the manifold changes to a trivial state.

}, issn = {0036-8075}, doi = {10.1126/science.aam9031}, url = {http://science.sciencemag.org/content/360/6396/1429}, author = {Sugawa, Seiji and Salces-Carcoba, Francisco and Perry, Abigail R. and Yue, Yuchen and Ian B Spielman} } @article { ISI:000432019800008, title = {Semiclassical approach to finite-temperature quantum annealing with trapped ions}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {5}, year = {2018}, month = {MAY 7}, pages = {052310}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.052310}, author = {Raventos, David and Grass, Tobias and Julia-Diaz, Bruno and Lewenstein, Maciej} } @article { ISI:000419101400002, title = {Single-Atom Transistor as a Precise Magnetic Field Sensor}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {1}, year = {2018}, month = {JAN 3}, pages = {013401}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.013401}, author = {Jachymski, Krzysztof and Wasak, Tomasz and Idziaszek, Zbigniew and Julienne, Paul S. and Negretti, Antonio and Calarco, Tommaso} } @article { ISI:000430383200001, title = {Single-Particle Mobility Edge in a One-Dimensional Quasiperiodic Optical Lattice}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {16}, year = {2018}, month = {APR 19}, pages = {160404}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.160404}, author = {Luschen, Henrik P. and Scherg, Sebastian and Kohlert, Thomas and Schreiber, Michael and Bordia, Pranjal and Li, Xiao and S. Das Sarma and Bloch, Immanuel} } @article {10071, title = {A single-photon switch and transistor enabled by a solid-state quantum memory}, journal = {Science}, volume = {361}, year = {2018}, pages = {57}, url = {http://science.sciencemag.org/content/361/6397/57}, author = {Sun, Shuo and Kim, Hyochul and Zhouchen Luo and Glenn S Solomon and Edo Waks} } @article { ISI:000427598600006, title = {Spectral asymmetry of atoms in the van der Waals potential of an optical nanofiber}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {3}, year = {2018}, month = {MAR 15}, pages = {032509}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.032509}, author = {Patterson, B. D. and Solano, P. and Julienne, P. S. and Orozco, L. A. and Rolston, S. L.} } @article {ISI:000419619800004, title = {Spectrum Estimation of Density Operators with Alkaline-Earth Atoms}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {2}, year = {2018}, month = {JAN 9}, pages = {025301}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We show that Ramsey spectroscopy of fermionic alkaline-earth atoms in a square-well trap provides an efficient and accurate estimate for the eigenspectrum of a density matrix whose n copies are stored in the nuclear spins of n such atoms. This spectrum estimation is enabled by the high symmetry of the interaction Hamiltonian, dictated, in turn, by the decoupling of the nuclear spin from the electrons and by the shape of the square-well trap. Practical performance of this procedure and its potential applications to quantum computing and time keeping with alkaline-earth atoms are discussed.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.025301}, author = {Beverland, Michael E. and Haah, Jeongwan and Alagic, Gorjan and Campbell, Gretchen K. and Rey, Ana Maria and Gorshkov, Alexey V.} } @article { ISI:000452316100001, title = {Spin decoherence in a two-qubit CPHASE gate: the critical role of tunneling noise}, journal = {NPJ QUANTUM INFORMATION}, volume = {4}, year = {2018}, month = {NOV 27}, pages = {62}, abstract = {Rapid progress in semiconductor spin qubits has enabled experimental demonstrations of a two-qubit logic gate. Understanding spin decoherence in a two-qubit logic gate is necessary for optimal qubit operation. We study spin decoherence due to 1/f charge noise for two electrons in a double quantum dot used for a two-qubit controlled-phase gate. In contrast to the usual belief, spin decoherence can be dominated by the tunneling noise from 1/f charge noise instead of the detuning noise. Tunneling noise can dominate because the effect of tunneling noise on the spin qubit is first order in the charge admixture; while the effect of the detuning noise is only second order. The different orders of contributions result in different detuning dependence of the decoherence, which provides a way to identify the noise source. We find that decoherence in a recent two-qubit experiment was dominated by the tunneling noise from 1/f charge noise. The results illustrate the importance of considering tunneling noise to design optimal operation of spin qubits.}, issn = {2056-6387}, doi = {10.1038/s41534-018-0112-0}, author = {Huang, Peihao and Zimmerman, Neil M. and Bryant, Garnett W.} } @article { ISI:000450547500006, title = {Spin relaxation of a donor electron coupled to interface states}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {19}, year = {2018}, month = {NOV 16}, pages = {195307}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.195307}, author = {Huang, Peihao and Bryant, Garnett W.} } @article { ISI:000453476900018, title = {Spin-Mechanical Coupling of an InAs Quantum Dot Embedded in a Mechanical Resonator}, journal = {PHYSICAL REVIEW LETTERS}, volume = {121}, number = {24}, year = {2018}, month = {DEC 14}, pages = {246801}, abstract = {We demonstrate strain-induced coupling between a hole spin in a quantum dot and mechanical motion of a cantilever. The optical transitions of quantum dots integrated into GaAs mechanical resonators are measured synchronously with the motion of the driven resonators. In a Voigt magnetic field, both electron and hole spin splittings are measured, showing negligible change for the electron spin but a large change for the hole spin of up to 36\%. This large effect is attributed to the stronger spin orbit interaction of holes compared to electrons.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.121.246801}, author = {Carter, S. G. and Bracker, A. S. and Bryant, G. W. and Kim, M. and Kim, C. S. and Zalalutdinov, M. K. and Yakes, M. K. and Czarnocki, C. and Casara, J. and Scheibner, M. and Gammon, D.} } @article {9321, title = {Spin-optomechanical coupling between light and a nanofiber torsional mode}, journal = {Opt. Lett.}, volume = {43}, year = {2018}, month = {Apr}, pages = {1534{\textendash}1537}, abstract = {Light that carries linear or angular momentum can interact with a mechanical object, giving rise to optomechanical effects. In particular, a photon can transfer its intrinsic angular momentum to an object when the object either absorbs the photon or changes the photon polarization, as in an action/reaction force pair. Here, we demonstrate resonant driving of torsional mechanical modes of a single-mode tapered optical nanofiber using spin angular momentum. The nanofiber torsional mode spectrum is characterized by polarimetry, showing narrow natural resonances (Q\&\#x2248;2,000). By sending amplitude-modulated light through the nanofiber, we resonantly drive individual torsional modes as a function of the light polarization. By varying the input polarization to the fiber, we find the largest amplification of a mechanical oscillation (\>35\&\#x2009;\&\#x2009;dB) is observed when driving the system with light containing longitudinal spin on the nanofiber waist. These results present optical nanofibers as a platform suitable for quantum spin-optomechanics experiments.

}, keywords = {Fiber optics, Heterodyne, Nanophotonics and photonic crystals, Optomechanics}, doi = {10.1364/OL.43.001534}, url = {http://ol.osa.org/abstract.cfm?URI=ol-43-7-1534}, author = {Eliot F. Fenton and Adnan Khan and Pablo Solano and Luis A. Orozco and Fredrik K. Fatemi} } @article { ISI:000441857400004, title = {Spinor Bose-Einstein-condensate phase-sensitive amplifier for SU(1,1) interferometry}, journal = {PHYSICAL REVIEW A}, volume = {98}, number = {2}, year = {2018}, month = {AUG 16}, pages = {023620}, issn = {2469-9926}, doi = {10.1103/PhysRevA.98.023620}, author = {Wrubel, J. P. and Schwettmann, A. and Fahey, D. P. and Glassman, Z. and Pechkis, H. K. and Griffin, P. F. and Barnett, R. and Tiesinga, E. and Lett, P. D.} } @article { ISI:000448599200008, title = {Structure of correlated worldline theories of quantum gravity}, journal = {PHYSICAL REVIEW D}, volume = {98}, number = {8}, year = {2018}, month = {OCT 29}, pages = {084052}, issn = {2470-0010}, doi = {10.1103/PhysRevD.98.084052}, author = {Barvinsky, A. O. and Carney, D. and Stamp, P. C. E.} } @article { ISI:000441478300016, title = {Super-Radiant Emission from Quantum Dots in a Nanophotonic Waveguide}, journal = {NANO LETTERS}, volume = {18}, number = {8}, year = {2018}, month = {AUG}, pages = {4734-4740}, issn = {1530-6984}, doi = {10.1021/acs.nanolett.8b01133}, author = {Kim, Je-Hyung and Aghaeimeibodi, Shahriar and Richardson, Christopher J. K. and Leavitt, Richard P. and Waks, Edo} } @article {ISI:000423107800020, title = {Synthetic clock transitions via continuous dynamical decoupling}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {1}, year = {2018}, month = {JAN 16}, pages = {013407}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Decoherence of quantum systems due to uncontrolled fluctuations of the environment presents fundamental obstacles in quantum science. Clock transitions which are insensitive to such fluctuations are used to improve coherence, however, they are not present in all systems or for arbitrary system parameters. Here we create a trio of synthetic clock transitions using continuous dynamical decoupling in a spin-1 Bose-Einstein condensate in which we observe a reduction of sensitivity to magnetic-field noise of up to four orders of magnitude; this work complements the parallelwork byAnderson et al. {[}R. P. Anderson et al., following paper, Phys. Rev. A 97, 013408 (2018)]. In addition, using a concatenated scheme, we demonstrate suppression of sensitivity to fluctuations in our control fields. These field-insensitive states represent an ideal foundation for the next generation of cold-atom experiments focused on fragile many-body phases relevant to quantum magnetism, artificial gauge fields, and topological matter.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.013407}, author = {Trypogeorgos, D. and Valdes-Curiel, A. and Lundblad, N. and Ian B Spielman} } @conference { ISI:000450231900031, title = {A Table-Top Graphene Quantized Hall Standard}, booktitle = {2018 CONFERENCE ON PRECISION ELECTROMAGNETIC MEASUREMENTS (CPEM 2018)}, year = {2018}, note = {Conference on Precision Electromagnetic Measurements (CPEM), Paris, FRANCE, JUL 08-13, 2018}, keywords = {binary cryogenic current comparator, direct current comparator, epitaxial graphene, quantized Hall resistance, standard resistor}, isbn = {978-1-5386-0974-3}, author = {Rigosi, Albert F. and Panna, Alireza R. and Payagala, Shamith U. and Jones, George R. and Kraft, Marlin E. and Kruskopf, Mattias and Wu, Bi-Yi and Lee, Hsin-Yen and Yang, Yanfei and Jarrett, Dean G. and Elmquist, Randolph E. and Newell, David B.} } @article { ISI:000454178600013, title = {Theory of Phonon-Mediated Superconductivity in Twisted Bilayer Graphene}, journal = {PHYSICAL REVIEW LETTERS}, volume = {121}, number = {25}, year = {2018}, month = {DEC 17}, pages = {257001}, abstract = {We present a theory of phonon-mediated superconductivity in near magic angle twisted bilayer graphene. Using a microscopic model for phonon coupling to moire band electrons, we find that phonons generate attractive interactions in both s- and d-wave pairing channels and that the attraction is strong enough to explain the experimental superconducting transition temperatures. Before including Coulomb repulsion, the s-wave channel is more favorable; however, on-site Coulomb repulsion can suppress s-wave pairing relative to d wave. The pair amplitude varies spatially with the moire period, and is identical in the two layers in the s-wave channel but phase shifted by pi in the d-wave channel. We discuss experiments that can distinguish the two pairing states.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.121.257001}, author = {Wu, Fengcheng and MacDonald, A. H. and Martin, Ivar} } @article { ISI:000428165400006, title = {Thermal management and non-reciprocal control of phonon flow via optomechanics}, journal = {NATURE COMMUNICATIONS}, volume = {9}, year = {2018}, month = {MAR 23}, pages = {1207}, issn = {2041-1723}, doi = {10.1038/s41467-018-03624-y}, author = {Seif, Alireza and DeGottardi, Wade and Esfarjani, Keivan and Hafezi, Mohammad} } @article { ISI:000444775000003, title = {Time-reversal and spatial-reflection symmetry localization anomalies in (2+1)-dimensional topological phases of matter}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {11}, year = {2018}, month = {SEP 17}, pages = {115129}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.115129}, author = {Barkeshli, Maissam and Cheng, Meng} } @article { ISI:000438196300002, title = {Topological band crossings in hexagonal materials}, journal = {PHYSICAL REVIEW MATERIALS}, volume = {2}, number = {7}, year = {2018}, month = {JUL 11}, pages = {074201}, issn = {2475-9953}, doi = {10.1103/PhysRevMaterials.2.074201}, author = {Zhang, J. and Chan, Y-H. and Chiu, C-K. and Vergniory, M. G. and Schoop, L. M. and Schnyder, A. P.} } @article { ISI:000437838000015, title = {Topological Exciton Fermi Surfaces in Two-Component Fractional Quantized Hall Insulators}, journal = {PHYSICAL REVIEW LETTERS}, volume = {121}, number = {2}, year = {2018}, month = {JUL 9}, pages = {026603}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.121.026603}, author = {Barkeshli, Maissam and Nayak, Chetan and Papic, Zlatko and Young, Andrea and Zaletel, Michael} } @article {ISI:000431525200001, title = {Topological lattice using multi-frequency radiation}, journal = {NEW JOURNAL OF PHYSICS}, volume = {20}, year = {2018}, month = {MAY 3}, pages = {055001}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {We describe a novel technique for creating an artificial magnetic field for ultracold atoms using a periodically pulsed pair of counter propagating Raman lasers that drive transitions between a pair of internal atomic spin states: a multi-frequency coupling term. In conjunction with a magnetic field gradient, this dynamically generates a rectangular lattice with a non-staggered magnetic flux. For a wide range of parameters, the resulting Bloch bands have non-trivial topology, reminiscent of Landau levels, as quantified by their Chern numbers.}, \%\%Address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}, keywords = {artificial gauge fields, Floquet, flux lattice}, issn = {1367-2630}, doi = {10.1088/1367-2630/aab7a3}, author = {Andrijauskas, Tomas and Ian B Spielman and Juzeliunas, Gediminas} } @article { ISI:000439973300004, title = {Topological phases, edge modes, and the Hofstadter butterfly in coupled Su-Schrieffer-Heeger systems}, journal = {PHYSICAL REVIEW B}, volume = {98}, number = {2}, year = {2018}, month = {JUL 27}, pages = {024205}, issn = {2469-9950}, doi = {10.1103/PhysRevB.98.024205}, author = {Padavic, Karmela and Hegde, Suraj S. and DeGottardi, Wade and Vishveshwara, Smitha} } @article {8956, title = {A topological quantum optics interface}, journal = {Science}, volume = {359}, year = {2018}, chapter = {666}, doi = {10.1126/science.aaq0327}, url = {http://science.sciencemag.org/content/359/6376/666}, author = {Barik, Sabyasachi and Aziz Karasahin and Christopher Flower and Cai, Tao and Miyake, H. and DeGottardi, Wade and Mohammad Hafezi and Edo Waks} } @article {10301, title = {A topological source of quantum light}, journal = {Nature}, year = {2018}, url = {https://www.nature.com/articles/s41586-018-0478-3}, author = {S Mittal and Elizabeth A Goldschmidt and Hafezi, Mohammad} } @article { ISI:000445622500049, title = {A topological source of quantum light}, journal = {NATURE}, volume = {561}, number = {7724}, year = {2018}, month = {SEP 27}, pages = {502+}, issn = {0028-0836}, doi = {10.1038/s41586-018-0478-3}, author = {Mittal, Sunil and Goldschmidt, Elizabeth A. and Hafezi, Mohammad} } @article { ISI:000446802800024, title = {Towards epitaxial graphene p-n junctions as electrically programmable quantum resistance standards}, journal = {SCIENTIFIC REPORTS}, volume = {8}, year = {2018}, month = {OCT 9}, pages = {15018}, issn = {2045-2322}, doi = {10.1038/s41598-018-33466-z}, author = {Hu, Jiuning and Rigosi, Albert F. and Kruskopf, Mattias and Yang, Yanfei and Wu, Bi-Yi and Tian, Jifa and Panna, Alireza R. and Lee, Hsin-Yen and Payagala, Shamith U. and Jones, George R. and Kraft, Marlin E. and Jarrett, Dean G. and Watanabe, Kenji and Taniguchi, Takashi and Elmquist, Randolph E. and Newell, David B.} } @article { ISI:000423887500033, title = {Towards replacing resistance thermometry with photonic thermometry}, journal = {SENSORS AND ACTUATORS A-PHYSICAL}, volume = {269}, year = {2018}, month = {JAN 1}, pages = {308-312}, keywords = {Photonic crystal cavity, Photonic thermometry resistance thermometer}, issn = {0924-4247}, doi = {10.1016/j.sna.2017.11.055}, author = {Klimov, Nikolai and Purdy, Thomas and Ahmed, Zeeshan} } @article { ISI:000440602300120, title = {Towards superconductivity in p-type delta-doped Si/Al/Si heterostructures}, journal = {AIP ADVANCES}, volume = {8}, number = {7}, year = {2018}, month = {JUL}, pages = {075329}, issn = {2158-3226}, doi = {10.1063/1.5045338}, author = {Ramanayaka, A. N. and Kim, Hyun-Soo and Hagmann, J. A. and Murray, R. E. and Tang, Ke and Meisenkothen, F. and Zhang, H. R. and Bendersky, L. A. and Davydov, A. V. and Zimmerman, Neil M. and Richter, C. A. and Pomeroy, J. M.} } @conference { ISI:000450231900289, title = {Transport of NIST Graphene Quantized Hall Devices and Comparison with AIST Gallium-Arsenide Quantized Hall Devices}, booktitle = {2018 CONFERENCE ON PRECISION ELECTROMAGNETIC MEASUREMENTS (CPEM 2018)}, year = {2018}, note = {Conference on Precision Electromagnetic Measurements (CPEM), Paris, FRANCE, JUL 08-13, 2018}, keywords = {carrier density, cryogenic current comparator, graphene, quantized Hall resistance, standard resistor}, isbn = {978-1-5386-0974-3}, author = {Jarrett, Dean G. and Oe, Takehiko and Elmquist, Randolph E. and Kaneko, Nobu-hisa and Rigosi, Albert F. and Wu, Bi-Yi and Lee, Hsin-Yen and Yang, Yanfei} } @article { ISI:000432974400003, title = {Two Clock Transitions in Neutral Yb for the Highest Sensitivity to Variations of the Fine-Structure Constant}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {17}, year = {2018}, month = {APR 27}, pages = {173001}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.173001}, author = {Safronova, Marianna S. and Porsev, Sergey G. and Sanner, Christan and Ye, Jun} } @article { ISI:000435178200017, title = {Two-frequency operation of a Paul trap to optimise confinement of two species of ions}, journal = {INTERNATIONAL JOURNAL OF MASS SPECTROMETRY}, volume = {430}, year = {2018}, month = {JUL}, pages = {117-125}, keywords = {Ion trap, Multiple frequencies, Parametric heating}, issn = {1387-3806}, doi = {10.1016/j.ijms.2018.05.007}, author = {Foot, C. J. and Trypogeorgos, D. and Bentine, E. and Gardner, A. and Keller, M.} } @article { ISI:000428507500006, title = {Ultracold Anions for High-Precision Antihydrogen Experiments}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {13}, year = {2018}, month = {MAR 28}, pages = {133205}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.133205}, author = {Cerchiari, G. and Kellerbauer, A. and Safronova, M. S. and Safronova, U. I. and Yzombard, P.} } @article { ISI:000423107800027, title = {Ultracold atoms in multiple radio-frequency dressed adiabatic potentials}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {1}, year = {2018}, month = {JAN 16}, pages = {013616}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.013616}, author = {Harte, T. L. and Bentine, E. and Luksch, K. and Barker, A. J. and Trypogeorgos, D. and Yuen, B. and Foot, C. J.} } @conference { ISI:000450231900294, title = {Uncertainty of the Ohm Using Cryogenic and Non-Cryogenic Bridges}, booktitle = {2018 CONFERENCE ON PRECISION ELECTROMAGNETIC MEASUREMENTS (CPEM 2018)}, year = {2018}, note = {Conference on Precision Electromagnetic Measurements (CPEM), Paris, FRANCE, JUL 08-13, 2018}, keywords = {cryogenic current comparator, direct current comparator, quantized Hall resistance, standard resistor, traceability}, isbn = {978-1-5386-0974-3}, author = {Panna, Alireza R. and Kraft, Marlin E. and Rigosi, Albert F. and Jones, George R. and Payagala, Shamith U. and Kruskopf, Mattias and Jarrett, Dean G. and Elmquist, Randolph E.} } @article { ISI:000454419500004, title = {Unitary entanglement construction in hierarchical networks}, journal = {PHYSICAL REVIEW A}, volume = {98}, number = {6}, year = {2018}, month = {DEC 26}, pages = {062328}, abstract = {The construction of large-scale quantum computers will require modular architectures that allow physical resources to be localized in easy-to-manage packages. In this work we examine the impact of different graph structures on the preparation of entangled states. We begin by explaining a formal framework, the hierarchical product, in which modular graphs can be easily constructed. This framework naturally leads us to suggest a class of graphs, which we dub hierarchies. We argue that such graphs have favorable properties for quantum information processing, such as a small diameter and small total edge weight, and use the concept of Pareto efficiency to identify promising quantum graph architectures. We present numerical and analytical results on the speed at which large entangled states can be created on nearest-neighbor grids and hierarchy graphs. We also present a scheme for performing circuit placement-the translation from circuit diagrams to machine qubits-on quantum systems whose connectivity is described by hierarchies.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.98.062328}, author = {Bapat, Aniruddha and Eldredge, Zachary and Garrison, James R. and Deshpande, Abhinav and Chong, Frederic T. and Gorshkov, Alexey V.} } @article { ISI:000419468200001, title = {Universal many-body response of heavy impurities coupled to a Fermi sea: a review of recent progress}, journal = {REPORTS ON PROGRESS IN PHYSICS}, volume = {81}, number = {2}, year = {2018}, month = {FEB}, pages = {024401}, keywords = {Fermi gas, Feshbach resonances, functional determinants, non-equilibrium dynamics, orthogonality catastrophe, quantum impurities}, issn = {0034-4885}, doi = {10.1088/1361-6633/aa9593}, author = {Schmidt, Richard and Knap, Michael and Ivanov, Dmitri A. and You, Jhih-Shih and Cetina, Marko and Demler, Eugene} } @article {10436, title = {Unscrambling the physics of out-of-time-order correlators}, journal = {Nature Physics}, volume = {14}, year = {2018}, pages = {988{\textendash}990}, abstract = {Quantitative tools for measuring the propagation of information through quantum many-body systems, originally developed to study quantum chaos, have recently found many new applications from black holes to disordered spin systems.

}, isbn = {1745-2481}, doi = {10.1038/s41567-018-0295-5}, url = {https://doi.org/10.1038/s41567-018-0295-5}, author = {Swingle, Brian} } @article { ISI:000449675500001, title = {Unsupervised phase mapping of X-ray diffraction data by nonnegative matrix factorization integrated with custom clustering}, journal = {NPJ COMPUTATIONAL MATERIALS}, volume = {4}, year = {2018}, month = {AUG 6}, pages = {UNSP 43}, issn = {2057-3960}, doi = {10.1038/s41524-018-0099-2}, author = {Stanev, Valentin and Vesselinov, Velimir V. and Kusne, A. Gilad and Antoszewski, Graham and Takeuchi, Ichiro and Alexandrov, Boian S.} } @article { ISI:000423121900004, title = {Viscosity of a multichannel one-dimensional Fermi gas}, journal = {PHYSICAL REVIEW B}, volume = {97}, number = {4}, year = {2018}, month = {JAN 18}, pages = {045135}, issn = {2469-9950}, doi = {10.1103/PhysRevB.97.045135}, author = {DeGottardi, Wade and Matveev, K. A.} } @article {10331, title = {Weak-link Josephson Junctions Made from Topological Crystalline Insulators}, journal = {Phys. Rev. Lett.}, volume = {121}, year = {2018}, month = {Aug}, pages = {097701}, doi = {10.1103/PhysRevLett.121.097701}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.121.097701}, author = {Snyder, R. A. and Trimble, C. J. and Rong, C. C. and Folkes, P. A. and Taylor, P. J. and James R. Williams} } @article { ISI:000433032500022, title = {Weyl Semimetal to Metal Phase Transitions Driven by Quasiperiodic Potentials}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {20}, year = {2018}, month = {MAY 18}, pages = {207604}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.207604}, author = {Pixley, J. H. and Wilson, Justin H. and Huse, David A. and Gopalakrishnan, Sarang} } @article {ISI:000391848000004, title = {8 pi-periodic dissipationless ac Josephson effect on a quantum spin Hall edge via a quantum magnetic impurity}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {1}, year = {2017}, month = {JAN 9}, pages = {014505}, abstract = {Time-reversal invariance places strong constraints on the properties of the quantum spin Hall edge. One such restriction is the inevitability of dissipation in a Josephson junction between two superconductors formed on such an edge without the presence of interaction. Interactions and spin-conservation breaking are key ingredients for the realization of the dissipationless ac Josephson effect on such quantum spin Hall edges. We present a simple quantum impurity model that allows us to create a dissipationless fractional Josephson effect on a quantum spin Hall edge. We then use this model to substantiate a general argument that shows that any such nondissipative Josephson effect must necessarily be 8 pi periodic.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.014505}, author = {Hui, Hoi-Yin and Sau, Jay D.} } @article { ISI:000409458000006, title = {Above-threshold scattering about a Feshbach resonance for ultracold atoms in an optical collider}, journal = {NATURE COMMUNICATIONS}, volume = {8}, year = {2017}, month = {SEP 6}, issn = {2041-1723}, doi = {10.1038/s41467-017-00458-y}, author = {Horvath, Milena S. J. and Thomas, Ryan and Tiesinga, Eite and Deb, Amita B. and Kjaergaard, Niels} } @article { ISI:000408620800002, title = {Andreev bound states versus Majorana bound states in quantum dot-nanowire-superconductor hybrid structures: Trivial versus topological zero-bias conductance peaks}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {7}, year = {2017}, month = {AUG 30}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.075161}, author = {Liu, Chun-Xiao and Sau, Jay D. and Stanescu, Tudor D. and S. Das Sarma} } @article { ISI:000411472400012, title = {Bell{\textquoteright}s inequality and entanglement in qubits}, journal = {JOURNAL OF HIGH ENERGY PHYSICS}, number = {9}, year = {2017}, month = {SEP 20}, issn = {1029-8479}, doi = {10.1007/JHEP09(2017)100}, author = {Chang, Po-Yao and Chu, Su-Kuan and Ma, Chen-Te} } @article {ISI:000395511400052, title = {Brownian motion of solitons in a Bose-Einstein condensate}, journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, volume = {114}, number = {10}, year = {2017}, month = {MAR 7}, pages = {2503-2508}, abstract = {We observed and controlled the Brownian motion of solitons. We launched solitonic excitations in highly elongated Rb-87 Bose-Einstein condensates (BECs) and showed that a dilute background of impurity atoms in a different internal state dramatically affects the soliton. With no impurities and in one dimension (1D), these solitons would have an infinite lifetime, a consequence of integrability. In our experiment, the added impurities scatter off the much larger soliton, contributing to its Brownian motion and decreasing its lifetime. We describe the soliton{\textquoteright}s diffusive behavior using a quasi-1D scattering theory of impurity atoms interacting with a soliton, giving diffusion coefficients consistent with experiment.

}, issn = {0027-8424}, doi = {10.1073/pnas.1615004114}, author = {Aycock, Lauren M. and Hurst, Hilary M. and Efimkin, Dmitry K. and Genkina, Dina and Lu, Hsin-I and Galitski, Victor M. and Ian B Spielman} } @article { ISI:000413699200009, title = {Characterization of coherent population-trapped states in a circuit-QED Lambda system}, journal = {PHYSICAL REVIEW A}, volume = {96}, number = {4}, year = {2017}, month = {OCT 25}, issn = {2469-9926}, doi = {10.1103/PhysRevA.96.043858}, author = {Premaratne, Shavindra P. and Wellstood, F. C. and Palmer, B. S.} } @article { ISI:000407812000020, title = {Chemical-doping-driven crossover from graphene to {\textquoteleft}{\textquoteleft}ordinary metal{{\textquoteright}{\textquoteright}} in epitaxial graphene grown on SiC}, journal = {NANOSCALE}, volume = {9}, number = {32}, year = {2017}, month = {AUG 28}, pages = {11537-11544}, issn = {2040-3364}, doi = {10.1039/c7nr04155a}, author = {Chuang, Chiashain and Yang, Yanfei and Pookpanratana, Sujitra and Hacker, Christina A. and Liang, Chi-Te and Elmquist, Randolph E.} } @article { ISI:000405364100004, title = {Chiral anomaly and longitudinal magnetotransport in type-II Weyl semimetals}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {4}, year = {2017}, month = {JUL 13}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.045112}, author = {Sharma, Girish and Goswami, Pallab and Tewari, Sumanta} } @article {ISI:000417473700003, title = {Chiral spin condensation in a one-dimensional optical lattice}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {21}, year = {2017}, month = {DEC 7}, pages = {214502}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We study a spinor (two-component) Bose gas confined in a one-dimensional double-valley optical lattice which has a double-well structure in momentum space. Based on field theory analysis, it is found that spinor bosons in the double-valley band may form a spin-charge mixed chiral spin quasicondensate under certain conditions. Our numerical calculations in a concrete p-flux triangular ladder system confirm the robustness of the chiral spin order against interactions and quantum fluctuations. This exotic atomic Bose-Einstein condensate exhibits spatially staggered spin loop currents without any charge dynamics despite the complete absence of spin-orbit coupling in the system, creating an interesting approach to atom spintronics. The entanglement entropy scaling allows us to extract conformal-field-theory central charge and establish the low-energy effective field theory for the chiral spin condensate as a two-component Luttinger liquid. Our predictions should be detectable in atomic experiments through spin-resolved time-of-flight techniques.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.214502}, author = {Wu, Ying-Hai and Li, Xiaopeng and S. Das Sarma} } @article {ISI:000394087200002, title = {Competing orders and topology in the global phase diagram of pyrochlore iridates}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {8}, year = {2017}, month = {FEB 16}, pages = {085120}, abstract = {Strong electronic interactions and spin-orbit coupling can be conducive for realizing novel broken symmetry phases supporting quasiparticles with nontrivial band topology. 227 pyrochlore iridates provide a suitable material platform for studying such emergent phenomena where both topology and competing orders play important roles. In contrast to the most members of this material class, which are thought to display {\textquoteleft}{\textquoteleft}all-in-all-out{{\textquoteright}{\textquoteright}} (AIAO) type magnetically ordered low-temperature insulating ground states, Pr2Ir2O7 remains metallic while exhibiting {\textquoteleft}{\textquoteleft}spin-ice{{\textquoteright}{\textquoteright}} (SI) correlations at low temperatures. Additionally, this is the only 227 iridate compound, which exhibits a large anomalous Hall effect (AHE) along the {[}1,1,1] direction below 1.5 K, without possessing any measurable magnetic moment. By focusing on the normal state of 227 iridates, described by a parabolic semimetal with quadratic band touching, we use renormalization group analysis, mean-field theory, and phenomenological Landau theory as three complementary methods to construct a global phase diagram in the presence of generic local interactions among itinerant electrons of Ir ions. While the global phase diagram supports several competing multipolar orders, motivated by the phenomenology of 227 iridates we particularly emphasize the competition between AIAO and SI orders and how it can cause a mixed phase with {\textquoteleft}{\textquoteleft}three-in-one-out{{\textquoteright}{\textquoteright}} (3I1O) spin configurations. In terms of topological properties of Weyl quasiparticles of the 3I1O state, we provide an explanation for the magnitude and the direction of the observed AHE in Pr2Ir2O7. We propose a strain-induced enhancement of the onset temperature for AHE in thin films of Pr2Ir2O7 and additional experiments for studying competing orders in the vicinity of the metal-insulator transition. In addition to providing a theory for competing orders and magnetic properties of Pr2Ir2O7, the theoretical framework developed in this work should also be useful for a better understanding of competing multipolar orders in other correlated materials.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.085120}, author = {Goswami, Pallab and Roy, Bitan and S. Das Sarma} } @article {ISI:000417029900008, title = {Complete 3-Qubit Grover search on a programmable quantum computer}, journal = {NATURE COMMUNICATIONS}, volume = {8}, year = {2017}, month = {DEC 4}, pages = {1918}, publisher = {NATURE PUBLISHING GROUP}, type = {Article}, abstract = {The Grover quantum search algorithm is a hallmark application of a quantum computer with a well-known speedup over classical searches of an unsorted database. Here, we report results for a complete three-qubit Grover search algorithm using the scalable quantum computing technology of trapped atomic ions, with better-than-classical performance. Two methods of state marking are used for the oracles: a phase-flip method employed by other experimental demonstrations, and a Boolean method requiring an ancilla qubit that is directly equivalent to the state marking scheme required to perform a classical search. We also report the deterministic implementation of a Toffoli-4 gate, which is used along with Toffoli-3 gates to construct the algorithms; these gates have process fidelities of 70.5\% and 89.6\%, respectively.}, \%\%Address = {MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND}, issn = {2041-1723}, doi = {10.1038/s41467-017-01904-7}, author = {Figgatt, C. and Maslov, D. and Landsman, K. A. and Linke, N. M. and Debnath, S. and Monroe, C.} } @article { ISI:000406910800004, title = {Conductance of a superconducting Coulomb-blockaded Majorana nanowire}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {5}, year = {2017}, month = {AUG 4}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.054504}, author = {Chiu, Ching-Kai and Sau, Jay D. and S. Das Sarma} } @article {ISI:000391308200002, title = {Conductance spectroscopy of nontopological-topological superconductor junctions}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {2}, year = {2017}, month = {JAN 6}, pages = {020501}, abstract = {We calculate the zero-temperature differential conductance dI/dV of a voltage-biased one-dimensional junction between a nontopological and a topological superconductor for arbitrary junction transparency using the scattering matrix formalism. We consider two representative models for the topological superconductors: (i) spinful p-wave and (ii) s-wave with spin-orbit coupling and spin splitting. We verify that in the tunneling limit (small junction transparencies) where only single Andreev reflections contribute to the current, the conductance for voltages below the nontopological superconductor gap Delta(s) is zero and there are two symmetric conductance peaks appearing at eV = +/-Delta(s). with the quantized value (4-pi)2e(2)/h due to resonant Andreev reflection from the Majorana zero mode. However, when the junction transparency is not small, there is a finite conductance for e vertical bar V vertical bar \< Delta(s) arising from multiple Andreev reflections. The conductance at eV = +/-Delta(s). in this case is no longer quantized. In general, the conductance is particle-hole asymmetric except for sufficiently small transparencies. We further show that, for certain values of parameters, the tunneling conductance from a zero-energy conventional Andreev bound state can be made to mimic the conductance from a true Majorana mode.

}, issn = {2469-9950}, doi = {10.1102/PhysRevB.95.020501}, author = {Setiawan, F. and Cole, William S. and Sau, Jay D. and S. Das Sarma} } @article { ISI:000405197700004, title = {Continuous Symmetry Breaking in 1D Long-Range Interacting Quantum Systems}, journal = {PHYSICAL REVIEW LETTERS}, volume = {119}, number = {2}, year = {2017}, month = {JUL 11}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.119.023001}, author = {Maghrebi, Mohammad F. and Gong, Zhe-Xuan and Gorshkov, Alexey V.} } @article {7276, title = {Cooling a Harmonic Oscillator by Optomechanical Modification of Its Bath}, journal = {Phys. Rev. Lett.}, volume = {118}, year = {2017}, month = {May}, pages = {223602}, doi = {10.1103/PhysRevLett.118.223602}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.118.223602}, author = {Xu, Xunnong and Purdy, Thomas and Taylor, Jacob M.} } @article { ISI:000406334600006, title = {Correlated Photon Dynamics in Dissipative Rydberg Media}, journal = {PHYSICAL REVIEW LETTERS}, volume = {119}, number = {4}, year = {2017}, month = {JUL 26}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.119.043602}, author = {Zeuthen, Emil and Gullans, Michael J. and Maghrebi, Mohammad F. and Gorshkov, Alexey V.} } @article { ISI:000406292600001, title = {Coulomb blockade in fractional topological superconductors}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {4}, year = {2017}, month = {JUL 24}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.041123}, author = {Kim, Younghyun and Clarke, David J. and Lutchyn, Roman M.} } @article { ISI:000411687800006, title = {Coulomb drag and counterflow Seebeck coefficient in bilayer-graphene double layers}, journal = {NANO ENERGY}, volume = {40}, year = {2017}, month = {OCT}, pages = {42-48}, issn = {2211-2855}, doi = {10.1016/j.nanoen.2017.07.035}, author = {Hu, J. and Wu, T. and Tian, J. and Klimov, N. N. and Newell, D. B. and Chen, Y. P.} } @article {ISI:000415029000011, title = {Coupling Emission from Single Localized Defects in Two-Dimensional Semiconductor to Surface Plasmon Polaritons}, journal = {NANO LETTERS}, volume = {17}, number = {11}, year = {2017}, month = {NOV}, pages = {6564-6568}, publisher = {AMER CHEMICAL SOC}, type = {Article}, abstract = {Coupling of an atom-like emitter to surface plasmons provides a path toward significant optical non-linearity, which is essential in quantum information processing and quantum networks. A large coupling strength requires nanometer-scale positioning accuracy of the emitter near the surface of the plasmonic structure, which is challenging. We demonstrate the coupling of single localized defects in a tungsten diselenide (WSe2) monolayer self-aligned to the surface plasmon mode of a silver nanowire. The silver nanowire induces a strain gradient on the monolayer at the overlapping area, leading to the formation of localized defect emission sites that are intrinsically close to the surface plasmon. We measured an average coupling efficiency with a lower bound of 26\% +/- 11\% from the emitter into the plasmonic mode of the silver nanowire. This technique offers a way to achieve efficient coupling between plasmonic structures and localized defects of two-dimensional semiconductors.}, \%\%Address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, keywords = {2D semiconductors, defect emission, silver nanowire, Surface plasmon polaritons, transition metal dichalcogenide, tungsten diselenide}, issn = {1530-6984}, doi = {10.1021/acs.nanolett.7b02222}, author = {Cai, Tao and Dutta, Subhojit and Aghaeimeibodi, Shahriar and Yang, Zhili and Nah, Sanghee and Fourkas, John T. and Waks, Edo} } @article { ISI:000412435500003, title = {Decoherence of two coupled singlet-triplet spin qubits}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {16}, year = {2017}, month = {OCT 6}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.165301}, author = {Wu, Yang-Le and S. Das Sarma} } @article {ISI:000417492500001, title = {Demonstration of Two-Atom Entanglement with Ultrafast Optical Pulses}, journal = {PHYSICAL REVIEW LETTERS}, volume = {119}, number = {23}, year = {2017}, month = {DEC 8}, pages = {230501}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We demonstrate quantum entanglement of two trapped atomic ion qubits using a sequence of ultrafast laser pulses. Unlike previous demonstrations of entanglement mediated by the Coulomb interaction, this scheme does not require confinement to the Lamb-Dicke regime and can be less sensitive to ambient noise due to its speed. To elucidate the physics of an ultrafast phase gate, we generate a high entanglement rate using just ten pulses, each of similar to 20 ps duration, and demonstrate an entangled Bell state with (76 +/- 1)\% fidelity. These results pave the way for entanglement operations within a large collection of qubits by exciting only local modes of motion.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.119.230501}, author = {Wong-Campos, J. D. and Moses, S. A. and Johnson, K. G. and Monroe, C.} } @article {ISI:000396095500001, title = {Detecting topological superconductivity using low-frequency doubled Shapiro steps}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {6}, year = {2017}, month = {FEB 3}, pages = {060501}, abstract = {The fractional Josephson effect has been observed in many instances as a signature of a topological superconducting state containing zero-energy Majorana modes. We present a nontopological scenario which can produce a fractional Josephson effect generically in semiconductor-based Josephson junctions, namely, a resonant impurity bound state weakly coupled to a highly transparent channel. We show that the fractional ac Josephson effect can be generated by the Landau-Zener processes which flip the electron occupancy of the impurity bound state. The Josephson effect signature for Majorana modes become distinct from this nontopological scenario only at low frequency. We prove that a variant of the fractional ac Josephson effect, namely, the low-frequency doubled Shapiro steps, can provide a more reliable signature of the topological superconducting state.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.060501}, author = {Sau, Jay D. and Setiawan, F.} } @article { ISI:000414365000002, title = {Development of a new UHV/XHV pressure standard (cold atom vacuum standard)}, journal = {METROLOGIA}, volume = {54}, number = {6}, year = {2017}, month = {DEC}, pages = {S125-S132}, issn = {0026-1394}, doi = {10.1088/1681-7575/aa8a7b}, author = {Scherschligt, Julia and Fedchak, James A. and Barker, Daniel S. and Eckel, Stephen and Klimov, Nikolai and Makrides, Constantinos and Tiesinga, Eite} } @article { ISI:000407711300002, title = {Disorder-induced transitions in resonantly driven Floquet topological insulators}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {5}, year = {2017}, month = {AUG 16}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.054207}, author = {Titum, Paraj and Lindner, Netanel H. and Refael, Gil} } @article { ISI:000407923500006, title = {Dispersive optical detection of magnetic Feshbach resonances in ultracold gases}, journal = {PHYSICAL REVIEW A}, volume = {96}, number = {2}, year = {2017}, month = {AUG 18}, issn = {2469-9926}, doi = {10.1103/PhysRevA.96.022705}, author = {Sawyer, Bianca J. and Horvath, Milena S. J. and Tiesinga, Eite and Deb, Amita B. and Kjaergaard, Niels} } @article {ISI:000404466500004, title = {Dynamic zero modes of Dirac fermions and competing singlet phases of antiferromagnetic order}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {22}, year = {2017}, month = {JUN 30}, pages = {224438}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {In quantum spin systems, singlet phases often develop in the vicinity of an antiferromagnetic order. Typical settings for such problems arise when itinerant fermions are also present. In this paper, we develop a theoretical framework for \%\%Addressing such competing orders in an itinerant system, described by Dirac fermions strongly coupled to an O(3) nonlinear sigma model. We focus on two spatial dimensions, where upon disordering the antiferromagnetic order by quantum fluctuations the singular tunneling events also known as (anti) hedgehogs can nucleate competing singlet orders in the paramagnetic phase. In the presence of an isolated hedgehog configuration of the nonlinear sigma model field, we show that the fermion determinant vanishes as the dynamic Euclidean Dirac operator supports fermion zero modes of definite chirality. This provides a topological mechanism for suppressing the tunneling events. Using the methodology of quantum chromodynamics, we evaluate the fermion determinant in the close proximity of magnetic quantum phase transition, when the antiferromagnetic order-parameter field can be described by a dilute gas of hedgehogs and antihedgehogs. We show how the precise nature of emergent singlet order is determined by the overlap between dynamic fermion zero modes of opposite chirality, localized on the hedgehogs and antihedgehogs. For a Kondo-Heisenberg model on the honeycomb lattice, we demonstrate the competition between spin Peierls order and Kondo singlet formation, thereby elucidating its global phase diagram. We also discuss other physical problems that can be \%\%Addressed within this general framework.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.224438}, author = {Goswami, Pallab and Si, Qimiao} } @article {ISI:000393498700001, title = {Dynamical localization of coupled relativistic kicked rotors}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {6}, year = {2017}, month = {FEB 6}, abstract = {A periodically driven rotor is a prototypical model that exhibits a transition to chaos in the classical regime and dynamical localization (related to Anderson localization) in the quantum regime. In a recent work {[}Phys. Rev. B 94, 085120 (2016)], A. C. Keser et al. considered a many-body generalization of coupled quantum kicked rotors, and showed that in the special integrable linear case, dynamical localization survives interactions. By analogy with many-body localization, the phenomenon was dubbed dynamical many-body localization. In the present work, we study nonintegrable models of single and coupled quantum relativistic kicked rotors (QRKRs) that bridge the gap between the conventional quadratic rotors and the integrable linear models. For a single QRKR, we supplement the recent analysis of the angular-momentum-space dynamics with a study of the spin dynamics. Our analysis of two and three coupled QRKRs along with the proved localization in the many-body linear model indicate that dynamical localization exists in few-body systems. Moreover, the relation between QRKR and linear rotor models implies that dynamical many-body localization can exist in generic, nonintegrable many-body systems. And localization can generally result from a complicated interplay between Anderson mechanism and limiting integrability, since the many-body linear model is a high-angular-momentum limit of many-body QRKRs. We also analyze the dynamics of two coupled QRKRs in the highly unusual superballistic regime and find that the resonance conditions are relaxed due to interactions. Finally, we propose experimental realizations of the QRKR model in cold atoms in optical lattices.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.064303}, author = {Rozenbaum, Efim B. and Galitski, Victor} } @article { ISI:000407000100003, title = {Dynamically induced robust phonon transport and chiral cooling in an optomechanical system}, journal = {NATURE COMMUNICATIONS}, volume = {8}, year = {2017}, month = {AUG 7}, issn = {2041-1723}, doi = {10.1038/s41467-017-00247-7}, author = {Kim, Seunghwi and Xu, Xunnong and Taylor, Jacob M. and Bahl, Gaurav} } @article {7616, title = {Dynamics of trapped atoms around an optical nanofiber probed through polarimetry}, journal = {Opt. Lett.}, volume = {42}, year = {2017}, month = {Jun}, pages = {2283{\textendash}2286}, abstract = {The evanescent field outside an optical nanofiber (ONF) can create optical traps for neutral atoms. We present a non-destructive method to characterize such trapping potentials. An off-resonance linearly polarized probe beam that propagates through the ONF experiences a slow axis of polarization produced by trapped atoms on opposite sides along the ONF. The transverse atomic motion is imprinted onto the probe polarization through the changing atomic index of refraction. By applying a transient impulse, we measure a time-dependent polarization rotation of the probe beam that provides both a rapid and non-destructive measurement of the optical trapping frequencies.

}, keywords = {Fiber optics, Heterodyne, Laser trapping, Nanophotonics and photonic crystals}, doi = {10.1364/OL.42.002283}, url = {http://ol.osa.org/abstract.cfm?URI=ol-42-12-2283}, author = {Pablo Solano and Fredrik K. Fatemi and Luis A. Orozco and S. L. Rolston} } @article {ISI:000400662700004, title = {Effects of spin-orbit coupling on zero-energy bound states localized at magnetic impurities in multiband superconductors}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {20}, year = {2017}, month = {MAY 5}, abstract = {We investigate the effect of spin-orbit coupling on the in-gap bound states localized at magnetic impurities in multiband superconductors with unconventional (sign-changed) and conventional (sign-unchanged) s-wave pairing symmetry, which may be relevant to iron-based superconductors. Without spin-orbit coupling, for spin-singlet superconductors it is known that such bound states cross zero energy at a critical value of the impurity scattering strength and acquire a finite spin polarization. Moreover, the degenerate, spin-polarized, zero-energy bound states are unstable to applied Zeeman fields as well as a deviation of the impurity scattering strength away from criticality. Using a T-matrix formalism as well as analytical arguments, we show that, in the presence of spin-orbit coupling, the zero-energy bound states localized at magnetic impurities in unconventional, sign-changed, s-wave superconductors acquire surprising robustness to applied Zeeman fields and variation in the impurity scattering strength, an effect which is absent in the conventional, sign-unchanged, s-wave superconductors. Given that the iron-based multiband superconductors may possess a substantial spin-orbit coupling as seen in recent experiments, our results may provide one possible explanation to the recent observation of surprisingly robust zero bias scanning tunneling microscope peaks localized at magnetic impurities in iron-based superconductors provided the order parameter symmetry is sign changing s(+-)-wave.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.205107}, author = {Seo, Kangjun and Sau, Jay D. and Tewari, Sumanta} } @article {ISI:000416947500005, title = {Efimov States of Strongly Interacting Photons}, journal = {PHYSICAL REVIEW LETTERS}, volume = {119}, number = {23}, year = {2017}, month = {DEC 4}, pages = {233601}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We demonstrate the emergence of universal Efimov physics for interacting photons in cold gases of Rydberg atoms. We consider the behavior of three photons injected into the gas in their propagating frame, where a paraxial approximation allows us to consider them as massive particles. In contrast to atoms and nuclei, the photons have a large anisotropy between their longitudinal mass, arising from dispersion, and their transverse mass, arising from diffraction. Nevertheless, we show that, in suitably rescaled coordinates, the effective interactions become dominated by s-wave scattering near threshold and, as a result, give rise to an Efimov effect near unitarity. We show that the three-body loss of these Efimov trimers can be strongly suppressed and determine conditions under which these states are observable in current experiments. These effects can be naturally extended to probe few-body universality beyond three bodies, as well as the role of Efimov physics in the nonequilibrium, many-body regime.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.119.233601}, author = {Gullans, M. J. and Diehl, S. and Rittenhouse, S. T. and Ruzic, B. P. and D{\textquoteright}Incao, J. P. and Julienne, P. and Gorshkov, A. V. and Taylor, J. M.} } @article { ISI:000416023400007, title = {Electron temperature and tunnel coupling dependence of zero-bias and almost-zero-bias conductance peaks in Majorana nanowires}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {18}, year = {2017}, month = {NOV 22}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.184520}, author = {Setiawan, F. and Liu, Chun-Xiao and Sau, Jay D. and S. Das Sarma} } @article { ISI:000412747900001, title = {Electron transport in nodal-line semimetals}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {16}, year = {2017}, month = {OCT 11}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.161105}, author = {Syzranov, S. V. and Skinner, B.} } @article {ISI:000399783400014, title = {Emergent equilibrium in many-body optical bistability}, journal = {PHYSICAL REVIEW A}, volume = {95}, number = {4}, year = {2017}, month = {APR 17}, abstract = {Many-body systems constructed of quantum-optical building blocks can now be realized in experimental platforms ranging from exciton-polariton fluids to ultracold Rydberg gases, establishing a fascinating interface between traditional many-body physics and the driven-dissipative, nonequilibrium setting of cavity QED. At this interface, the standard techniques and intuitions of both fields are called into question, obscuring issues as fundamental as the role of fluctuations, dimensionality, and symmetry on the nature of collective behavior and phase transitions. Here, we study the driven-dissipative Bose-Hubbard model, a minimal description of numerous atomic, optical, and solid-state systems in which particle loss is countered by coherent driving. Despite being a lattice version of optical bistability, a foundational and patently nonequilibrium model of cavity QED, the steady state possesses an emergent equilibrium description in terms of a classical Ising model. We establish this picture by making new connections between traditional techniques from many-body physics (functional integrals) and quantum optics (the system-size expansion). To lowest order in a controlled expansion-organized around the experimentally relevant limit of weak interactions-the full quantum dynamics reduces to nonequilibrium Langevin equations, which support a phase transition described by model A of the Hohenberg-Halperin classification. Numerical simulations of the Langevin equations corroborate this picture, revealing that canonical behavior associated with the Ising model manifests readily in simple experimental observables.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.95.043826}, author = {Foss-Feig, M. and Niroula, P. and Young, J. T. and Hafezi, M. and Gorshkov, A. V. and Wilson, R. M. and Maghrebi, M. F.} } @article { ISI:000415167000009, title = {Enhancing quantum order with fermions by increasing species degeneracy}, journal = {PHYSICAL REVIEW A}, volume = {96}, number = {5}, year = {2017}, month = {NOV 15}, issn = {2469-9926}, doi = {10.1103/PhysRevA.96.053621}, author = {Najafi, Khadijeh and Maska, M. M. and Dixon, Kahlil and Julienne, P. S. and Freericks, J. K.} } @article { ISI:000413897900001, title = {Enriched axial anomaly in Weyl materials}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {16}, year = {2017}, month = {OCT 30}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.161115}, author = {Raines, Zachary M. and Galitski, Victor M.} } @conference {ISI:000423026400014, title = {Entangled Photons in 2D Topological Photonic Systems}, booktitle = {ACTIVE PHOTONIC PLATFORMS IX}, series = {Proceedings of SPIE}, volume = {10345}, year = {2017}, note = {Conference on Active Photonic Platforms IX, San Diego, CA, AUG 06-10, 2017}, pages = {UNSP 103451U}, publisher = {SPIE}, organization = {SPIE}, type = {Proceedings Paper}, abstract = {We study transport of time-bin entangled photon pairs in a 2D topological photonic system of coupled ring resonators. We show that the transport through edge bands preserves temporal correlations of input photons. Furthermore, edge transport is robust against system disorder and only marginally affects the temporal correlations of photons. In contrast, transport through bulk band leads to unwanted bunching/anti-bunching of photons and the probability of bunching/anti-bunching increases with increasing disorder. Finally, we discuss our experimentally efforts to demonstrate the robustness of edge states for quantum transport.}, \%\%Address = {1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA}, keywords = {edge states, quantum transport, Topological photonics}, isbn = {978-1-5106-1148-1; 978-1-5106-1147-4}, issn = {0277-786X}, doi = {10.1117/12.2275292}, author = {Mittal, Sunil and Orrc, Venkata Vikram and Hafezi, Mohammad}, editor = {Subramania, GS and Foteinopoulou, S} } @article { ISI:000406665400001, title = {Entanglement Area Laws for Long-Range Interacting Systems}, journal = {PHYSICAL REVIEW LETTERS}, volume = {119}, number = {5}, year = {2017}, month = {JUL 31}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.119.050501}, author = {Gong, Zhe-Xuan and Foss-Feig, Michael and Brandao, Fernando G. S. L. and Gorshkov, Alexey V.} } @article { ISI:000413668800012, title = {Evidence for magnetic Weyl fermions in a correlated metal}, journal = {NATURE MATERIALS}, volume = {16}, number = {11}, year = {2017}, month = {NOV}, pages = {1090+}, issn = {1476-1122}, doi = {10.1038/NMAT4987}, author = {Kuroda, K. and Tomita, T. and Suzuki, M. -T. and Bareille, C. and Nugroho, A. A. and Goswami, P. and Ochi, M. and Ikhlas, M. and Nakayama, M. and Akebi, S. and Noguchi, R. and Ishii, R. and Inami, N. and Ono, K. and Kumigashira, H. and Varykhalov, A. and Muro, T. and Koretsune, T. and Arita, R. and Shin, S. and Kondo, Takeshi and Nakatsuji, S.} } @article { ISI:000410860100003, title = {Exact sampling hardness of Ising spin models}, journal = {PHYSICAL REVIEW A}, volume = {96}, number = {3}, year = {2017}, month = {SEP 14}, issn = {2469-9926}, doi = {10.1103/PhysRevA.96.032324}, author = {Fefferman, B. and Foss-Feig, M. and Gorshkov, A. V.} } @article {ISI:000400772100005, title = {Exactly soluble model of boundary degeneracy}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {4}, year = {2017}, month = {JAN 25}, abstract = {We investigate the topological degeneracy that can be realized in Abelian fractional quantum spin Hall states with multiply connected gapped boundaries. Such a topological degeneracy (also dubbed as {\textquoteleft}{\textquoteleft}boundary degeneracy{{\textquoteright}{\textquoteright}}) does not require superconducting proximity effect and can be created by simply applying a depletion gate to the quantum spin Hall material and using a generic spin-mixing term (e.g., due to backscattering) to gap out the edge modes. We construct an exactly soluble microscopic model manifesting this topological degeneracy and solve it using the recently developed technique {[}S. Ganeshan and M. Levin, Phys. Rev. B 93, 075118 (2016)]. The corresponding string operators spanning this degeneracy are explicitly calculated. It is argued that the proposed scheme is experimentally reasonable.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.045309}, author = {Ganeshan, Sriram and Gorshkov, Alexey V. and Gurarie, Victor and Galitski, Victor M.} } @article {6876, title = {Experimental comparison of two quantum computing architectures}, journal = {Proceedings of the National Academy of Sciences}, volume = {114}, year = {2017}, pages = {3305-3310}, abstract = {We run a selection of algorithms on two state-of-the-art 5-qubit quantum computers that are based on different technology platforms. One is a publicly accessible superconducting transmon device (www.research.ibm.com/ibm-q) with limited connectivity, and the other is a fully connected trapped-ion system. Even though the two systems have different native quantum interactions, both can be programed in a way that is blind to the underlying hardware, thus allowing a comparison of identical quantum algorithms between different physical systems. We show that quantum algorithms and circuits that use more connectivity clearly benefit from a better-connected system of qubits. Although the quantum systems here are not yet large enough to eclipse classical computers, this experiment exposes critical factors of scaling quantum computers, such as qubit connectivity and gate expressivity. In addition, the results suggest that codesigning particular quantum applications with the hardware itself will be paramount in successfully using quantum computers in the future.

}, doi = {10.1073/pnas.1618020114}, url = {http://www.pnas.org/content/114/13/3305.abstract}, author = {Linke, Norbert M. and Maslov, Dmitri and Roetteler, Martin and Debnath, Shantanu and Figgatt, Caroline and Landsman, Kevin A. and Wright, Kenneth and Monroe, Christopher} } @article { ISI:000411592600023, title = {Experimental phase diagram of zero-bias conductance peaks in superconductor/semiconductor nanowire devices}, journal = {SCIENCE ADVANCES}, volume = {3}, number = {9}, year = {2017}, month = {SEP}, issn = {2375-2548}, doi = {10.1126/sciadv.1701476}, author = {Chen, Jun and Yu, Peng and Stenger, John and Hocevar, Moira and Car, Diana and Plissard, Sebastien R. and Bakkers, Erik P. A. M. and Stanescu, Tudor D. and Frolov, Sergey M.} } @article { ISI:000412979000001, title = {Experimental Study of Optimal Measurements for Quantum State Tomography}, journal = {PHYSICAL REVIEW LETTERS}, volume = {119}, number = {15}, year = {2017}, month = {OCT 13}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.119.150401}, author = {Sosa-Martinez, H. and Lysne, N. K. and Baldwin, C. H. and Kalev, A. and Deutsch, I. H. and Jessen, P. S.} } @article { ISI:000415087100002, title = {Experimentally accessible topological quality factor for wires with zero energy modes}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {20}, year = {2017}, month = {NOV 14}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.201109}, author = {Clarke, David J.} } @article { ISI:000412061700002, title = {Extracting Entanglement Geometry from Quantum States}, journal = {PHYSICAL REVIEW LETTERS}, volume = {119}, number = {14}, year = {2017}, month = {OCT 2}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.119.140502}, author = {Hyatt, Katharine and Garrison, James R. and Bauer, Bela} } @article { ISI:000415568700001, title = {Fast pulse sequences for dynamically corrected gates in singlet-triplet qubits}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {19}, year = {2017}, month = {NOV 17}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.195424}, author = {Throckmorton, Robert E. and Zhang, Chengxian and Yang, Xu-Chen and Wang, Xin and Barnes, Edwin and S. Das Sarma} } @article { ISI:000413663300001, title = {Fast Quantum State Transfer and Entanglement Renormalization Using Long-Range Interactions}, journal = {PHYSICAL REVIEW LETTERS}, volume = {119}, number = {17}, year = {2017}, month = {OCT 25}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.119.170503}, author = {Eldredge, Zachary and Gong, Zhe-Xuan and Young, Jeremy T. and Moosavian, Ali Hamed and Foss-Feig, Michael and Gorshkov, Alexey V.} } @article {7741, title = {Fault-tolerant quantum error detection}, journal = {Science Advances}, volume = {3}, year = {2017}, abstract = {Quantum computers will eventually reach a size at which quantum error correction becomes imperative. Quantum information can be protected from qubit imperfections and flawed control operations by encoding a single logical qubit in multiple physical qubits. This redundancy allows the extraction of error syndromes and the subsequent detection or correction of errors without destroying the logical state itself through direct measurement. We show the encoding and syndrome measurement of a fault-tolerantly prepared logical qubit via an error detection protocol on four physical qubits, represented by trapped atomic ions. This demonstrates the robustness of a logical qubit to imperfections in the very operations used to encode it. The advantage persists in the face of large added error rates and experimental calibration errors.

}, doi = {10.1126/sciadv.1701074}, url = {http://advances.sciencemag.org/content/3/10/e1701074}, author = {Linke, Norbert M. and Gutierrez, Mauricio and Landsman, Kevin A. and Figgatt, Caroline and Debnath, Shantanu and Brown, Kenneth R. and Monroe, Christopher} } @article {ISI:000402483300015, title = {Global Phase Diagram of a Three-Dimensional Dirty Topological Superconductor}, journal = {PHYSICAL REVIEW LETTERS}, volume = {118}, number = {22}, year = {2017}, month = {JUN 1}, pages = {227002}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We investigate the phase diagram of a three-dimensional, time-reversal symmetric topological superconductor in the presence of charge impurities and random s-wave pairing. Combining complimentary field theoretic and numerical methods, we show that the quantum phase transition between two topologically distinct paired states (or thermal insulators), described by thermal Dirac semimetal, remains unaffected in the presence of sufficiently weak generic randomness. At stronger disorder, however, these two phases are separated by an intervening thermal metallic phase of diffusive Majorana fermions. We show that across the insulator-insulator and metal-insulator transitions, normalized thermal conductance displays single parameter scaling, allowing us to numerically extract the critical exponents across them. The pertinence of our study in strong spin-orbit coupled, three-dimensional doped narrow gap semiconductors, such as CuxBi2Se3, is discussed.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.118.227002}, author = {Roy, Bitan and Alavirad, Yahya and Sau, Jay D.} } @article {ISI:000404469000012, title = {High-order multipole radiation from quantum Hall states in Dirac materials}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {23}, year = {2017}, month = {JUN 30}, pages = {235439}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We investigate the optical response of strongly disordered quantum Hall states in two-dimensional Dirac materials and find qualitatively different effects in the radiation properties of the bulk versus the edge. We show that the far-field radiation from the edge is characterized by large multipole moments (>50) due to the efficient transfer of angular momentum from the electrons into the scattered light. The maximum multipole transition moment is a direct measure of the coherence length of the edge states. Accessing these multipole transitions would provide new tools for optical spectroscopy and control of quantum Hall edge states. On the other hand, the far-field radiation from the bulk appears as random dipole emission with spectral properties that vary with the local disorder potential. We determine the conditions under which this bulk radiation can be used to image the disorder landscape. Such optical measurements can probe submicron-length scales over large areas and provide complementary information to scanning probe techniques. Spatially resolving this bulk radiation would serve as a novel probe of the percolation transition near half filling.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.235439}, author = {Gullans, Michael J. and Taylor, Jacob M. and Imamoglu, Atac and Ghaemi, Pouyan and Hafezi, Mohammad} } @article { ISI:000414531800009, title = {High-performance semiconductor quantum-dot single-photon sources}, journal = {NATURE NANOTECHNOLOGY}, volume = {12}, number = {11}, year = {2017}, month = {NOV}, pages = {1026-1039}, issn = {1748-3387}, doi = {10.1038/NNANO.2017.218}, author = {Senellart, Pascale and Solomon, Glenn and White, Andrew} } @article {ISI:000418393300031, title = {Hybrid Integration of Solid-State Quantum Emitters on a Silicon Photonic Chip}, journal = {NANO LETTERS}, volume = {17}, number = {12}, year = {2017}, month = {DEC}, pages = {7394-7400}, publisher = {AMER CHEMICAL SOC}, type = {Article}, abstract = {Scalable quantum photonic systems require efficient single photon sources coupled to integrated photonic devices. Solid-state quantum emitters can generate single photons with high efficiency, while silicon photonic circuits can manipulate them in an integrated device structure. Combining these two material platforms could, therefore, significantly increase the complexity of integrated quantum photonic devices. Here, we demonstrate hybrid integration of solid-state quantum emitters to a silicon photonic device. We develop a pick-and-place technique that can position epitaxially grown InAs/InP quantum dots emitting at telecom wavelengths on a silicon photonic chip deterministically with nanoscale precision. We employ an adiabatic tapering approach to transfer the emission from the quantum dots to the waveguide with high efficiency. We also incorporate an on-chip silicon-photonic beamsplitter to perform a Hanbury-Brown and Twiss measurement. Our approach could enable integration of precharacterized III-V quantum photonic devices into large-scale photonic structures to enable complex devices composed of many emitters and photons.}, \%\%Address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, keywords = {hybrid integration, Quantum Dots, Silicon quantum photonics, single photons}, issn = {1530-6984}, doi = {10.1021/acs.nanolett.7b03220}, author = {Kim, Je-Hyung and Aghaeimeibodi, Shahriar and Richardson, Christopher J. K. and Leavitt, Richard P. and Englund, Dirk and Waks, Edo} } @article { ISI:000411529000031, title = {Improved measurement of two-mode quantum correlations using a phase-sensitive amplifier}, journal = {OPTICS EXPRESS}, volume = {25}, number = {18}, year = {2017}, month = {SEP 4}, pages = {21301-21311}, issn = {1094-4087}, doi = {10.1364/OE.25.021301}, author = {Li, Tian and Anderson, Brian E. and Horrom, Travis and Schmittberger, Bonnie L. and Jones, Kevin M. and Lett, Paul D.} } @article {ISI:000418511300001, title = {Induced density correlations in a sonic black hole condensate}, journal = {SCIPOST PHYSICS}, volume = {3}, number = {3}, year = {2017}, month = {SEP}, pages = {UNSP 022}, publisher = {SCIPOST FOUNDATION}, type = {Article}, abstract = {Analog black / white hole pairs, consisting of a region of supersonic flow, have been achieved in a recent experiment by J. Steinhauer using an elongated Bose-Einstein condensate. A growing standing density wave, and a checkerboard feature in the density-density correlation function, were observed in the supersonic region. We model the density-density correlation function, taking into account both quantum fluctuations and the shot-to-shot variation of atom number normally present in ultracold-atom experiments. We find that quantum fluctuations alone produce some, but not all, of the features of the correlation function, whereas atom-number fluctuation alone can produce all the observed features, and agreement is best when both are included. In both cases, the density-density correlation is not intrinsic to the fluctuations, but rather is induced by modulation of the standing wave caused by the fluctuations.}, \%\%Address = {C/O J S CAUX, INST PHYSICS, UNIV AMSTERDAM, AMSTERDAM, 1098 XH, NETHERLANDS}, issn = {2542-4653}, doi = {10.21468/SciPostPhys.3.3.022}, author = {Wang, Yi-Hsieh and Jacobson, Ted and Edwards, Mark and Clark, Charles W.} } @article { ISI:000405364000001, title = {Interacting nodal-line semimetal: Proximity effect and spontaneous symmetry breaking}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {4}, year = {2017}, month = {JUL 12}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.041113}, author = {Roy, Bitan} } @article {ISI:000400662700001, title = {Interacting Weyl fermions: Phases, phase transitions, and global phase diagram}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {20}, year = {2017}, month = {MAY 5}, abstract = {We study the effects of short-range interactions on a generalized three-dimensional Weyl semimetal, where the band touching points act as the (anti) monopoles of Abelian Berry curvature of strength n. We show that any local interaction has a negative scaling dimension -2/n. Consequently, all Weyl semimetals are stable against weak short-range interactions. For sufficiently strong interactions, we demonstrate that the Weyl semimetal either undergoes a first-order transition into a band insulator or a continuous transition into a symmetry breaking phase. A translational symmetry breaking axion insulator and a rotational symmetry breaking semimetal are two prominent candidates for the broken symmetry phase. At the one-loop order, the correlation length exponent for continuous transitions is upsilon = n/2, indicating their non-Gaussian nature for any n > 1. We also discuss the scaling of the thermodynamic and transport quantities in general Weyl semimetals as well as inside broken symmetry phases.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.201102}, author = {Roy, Bitan and Goswami, Pallab and Juricic, Vladimir} } @article {ISI:000419193700019, title = {Interfacing a quantum dot with a spontaneous parametric down-conversion source}, journal = {QUANTUM SCIENCE AND TECHNOLOGY}, volume = {2}, number = {3}, year = {2017}, month = {SEP 1}, pages = {UNSP 034016}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {Quantum networks require interfacing stationary and flying qubits. These flying qubits are usually nonclassical states of light. Here we consider two of the leading source technologies for nonclassical light, spontaneous parametric down-conversion and single semiconductor quantum dots. Down-conversion delivers high-grade entangled photon pairs, whereas quantum dots excel at producing single photons. We report on an experiment that joins these two technologies and investigates the conditions under which optimal interference between these dissimilar light sources may be achieved.}, \%\%Address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}, keywords = {heralded single photons, Hong-Ou-Mandel interference, Quantum Dots, quantum interfaces}, issn = {2058-9565}, doi = {10.1088/2058-9565/aa7b65}, author = {Huber, Tobias and Prilmueller, Maximilian and Sehner, Michael and Solomon, Glenn S. and Predojevic, Ana and Weihs, Gregor} } @article {ISI:000391305600002, title = {Intrinsic decoherence in isolated quantum systems}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {1}, year = {2017}, month = {JAN 4}, pages = {014202}, abstract = {We study the intrinsic, disorder-induced decoherence of an isolated quantum system under its own dynamics. Specifically, we investigate the characteristic time scale (i.e., the decoherence time) associated with an interacting many-body system losing the memory of its initial state. To characterize the erasure of the initial state memory, we define a time scale, the intrinsic decoherence time, by thresholding the gradual decay of the disorder-averaged return probability. We demonstrate the system-size independence of the intrinsic decoherence time in different models, and we study its dependence on the disorder strength. We find that the intrinsic decoherence time increases monotonically as the disorder strength increases in accordance with the relaxation of locally measurable quantities. We investigate several interacting spin (e.g., Ising and Heisenberg) and fermion (e.g., Anderson and Aubry-Andre) models to obtain the intrinsic decoherence time as a function of disorder and interaction strength.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.014202}, author = {Wu, Yang-Le and Deng, Dong-Ling and Li, Xiaopeng and S. Das Sarma} } @article {6531, title = {An Introduction to the New SI}, journal = {The Physics Teacher}, volume = {55}, year = {2017}, pages = {16-21}, doi = {10.1119/1.4972491}, url = {http://aapt.scitation.org/doi/abs/10.1119/1.4972491}, author = {Sandra Knotts and Peter J. Mohr and William D. Phillips} } @article { ISI:000408565900007, title = {Ionization enhancement and suppression by phase-locked ultrafast pulse pairs}, journal = {PHYSICAL REVIEW A}, volume = {96}, number = {2}, year = {2017}, month = {AUG 29}, issn = {2469-9926}, doi = {10.1103/PhysRevA.96.023425}, author = {Foote, David B. and Lin, Y. and Pi, Liang-Wen and Djiokap, J. M. Ngoko and Starace, Anthony F. and Hill, III, W. T.} } @article { ISI:000413372300001, title = {Ising quantum criticality in Majorana nanowires}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {13}, year = {2017}, month = {OCT 20}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.134517}, author = {Cole, William S. and Sau, Jay D. and S. Das Sarma} } @article {ISI:000400652700006, title = {Kinetic theory of dark solitons with tunable friction}, journal = {PHYSICAL REVIEW A}, volume = {95}, number = {5}, year = {2017}, month = {MAY 3}, abstract = {We study controllable friction in a system consisting of a dark soliton in a one-dimensional Bose-Einstein condensate coupled to a noninteracting Fermi gas. The fermions act as impurity atoms, not part of the original condensate, that scatter off of the soliton. We study semiclassical dynamics of the dark soliton, a particlelike object with negative mass, and calculate its friction coefficient. Surprisingly, it depends periodically on the ratio of interspecies (impurity-condensate) to intraspecies (condensate-condensate) interaction strengths. By tuning this ratio, one can access a regime where the friction coefficient vanishes. We develop a general theory of stochastic dynamics for negative-mass objects and find that their dynamics are drastically different from their positive-mass counterparts: they do not undergo Brownian motion. From the exact phase-space probability distribution function (i.e., in position and velocity), we find that both the trajectory and lifetime of the soliton are altered by friction, and the soliton can undergo Brownian motion only in the presence of friction and a confining potential. These results agree qualitatively with experimental observations by Aycock et al. {[}Proc. Natl. Acad. Sci. USA 114, 2503 (2017)] in a similar system with bosonic impurity scatterers.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.95.053604}, author = {Hurst, Hilary M. and Efimkin, Dmitry K. and Ian B Spielman and Galitski, Victor} } @article { ISI:000416232300009, title = {Lieb-Robinson bounds on n-partite connected correlation functions}, journal = {PHYSICAL REVIEW A}, volume = {96}, number = {5}, year = {2017}, month = {NOV 27}, issn = {2469-9926}, doi = {10.1103/PhysRevA.96.052334}, author = {Tran, Minh Cong and Garrison, James R. and Gong, Zhe-Xuan and Gorshkov, Alexey V.} } @article {8861, title = {Light-Induced Fractional Quantum Hall Phases in Graphene}, journal = {Phys. Rev. Lett.}, volume = {119}, year = {2017}, month = {Dec}, pages = {247403}, doi = {10.1103/PhysRevLett.119.247403}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.119.247403}, author = {Ghazaryan, Areg and Gra{\ss}, Tobias and Gullans, Michael J. and Ghaemi, Pouyan and Hafezi, Mohammad} } @article {ISI:000391851800003, title = {Logarithmic entanglement lightcone in many-body localized systems}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {2}, year = {2017}, month = {JAN 10}, pages = {024202}, abstract = {We theoretically study the response of a many-body localized system to a local quench from a quantum information perspective. We find that the local quench triggers entanglement growth throughout the whole system, giving rise to a logarithmic lightcone. This saturates the modified Lieb-Robinson bound for quantum information propagation in many-body localized systems previously conjectured based on the existence of local integrals of motion. In addition, near the localization-delocalization transition, we find that the final states after the local quench exhibit volume-law entanglement. We also show that the local quench induces a deterministic orthogonality catastrophe for highly excited eigenstates, where the typical wave-function overlap between the pre- and postquench eigenstates decays exponentially with the system size.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.024202}, author = {Deng, Dong-Ling and Li, Xiaopeng and Pixley, J. H. and Wu, Yang-Le and S. Das Sarma} } @article {6621, title = {Lyapunov Exponent and Out-of-Time-Ordered Correlator{\textquoteright}s Growth Rate in a Chaotic System}, journal = {Phys. Rev. Lett.}, volume = {118}, year = {2017}, month = {Feb}, pages = {086801}, doi = {10.1103/PhysRevLett.118.086801}, url = {http://link.aps.org/doi/10.1103/PhysRevLett.118.086801}, author = {Rozenbaum, Efim B. and Ganeshan, Sriram and Galitski, Victor} } @article { ISI:000416024600002, title = {Machine learning topological states}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {19}, year = {2017}, month = {NOV 22}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.195145}, author = {Deng, Dong-Ling and Li, Xiaopeng and S. Das Sarma} } @article {ISI:000404978900007, title = {Many-body localization in incommensurate models with a mobility edge}, journal = {ANNALEN DER PHYSIK}, volume = {529}, number = {7}, year = {2017}, month = {JUL}, pages = {1600399}, publisher = {WILEY-V C H VERLAG GMBH}, type = {Review}, abstract = {We review the physics of many-body localization in models with incommensurate potentials. In particular, we consider one-dimensional quasiperiodic models with single-particle mobility edges. A conventional perspective suggests that delocalized states act as a thermalizing bath for the localized states in the presence of of interactions. However, contrary to this intuition there is evidence that such systems can display non-ergodicity. This is in part due to the fact that the delocalized states do not have any kind of protection due to symmetry or topology and are thus susceptible to localization. A study of such incommensurate models, in the non-interacting limit, shows that they admit extended, partially extended, and fully localized many-body states. Non-interacting incommensurate models cannot thermalize dynamically and remain localized upon the introduction of interactions. In particular, for a certain range of energy, the system can host a non-ergodic extended (i.e. metallic) phase in which the energy eigenstates violate the eigenstate thermalization hypothesis (ETH) but the entanglement entropy obeys volume-law scaling. The level statistics and entanglement growth also indicate the lack of ergodicity in these models. The phenomenon of localization and non-ergodicity in a system with interactions despite the presence of single-particle delocalized states is closely related to the so-called many-body proximity effect and can also be observed in models with disorder coupled to systems with delocalized degrees of freedom. Many-body localization in systems with incommensurate potentials (without single-particle mobility edges) have been realized experimentally, and we show how this can be modified to study the the effects of such mobility edges. Demonstrating the failure of thermalization in the presence of a single-particle mobility edge in the thermodynamic limit would indicate a more robust violation of the ETH.}, \%\%Address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, issn = {0003-3804}, doi = {10.1002/andp.201600399}, author = {Deng, Dong-Ling and Ganeshan, Sriram and Li, Xiaopeng and Modak, Ranjan and Mukerjee, Subroto and Pixley, J. H.} } @article { ISI:000407777100007, title = {Mechanism of stimulated Hawking radiation in a laboratory Bose-Einstein condensate}, journal = {PHYSICAL REVIEW A}, volume = {96}, number = {2}, year = {2017}, month = {AUG 17}, issn = {2469-9926}, doi = {10.1103/PhysRevA.96.023616}, author = {Wang, Yi-Hsieh and Jacobson, Ted and Edwards, Mark and Clark, Charles W.} } @article {ISI:000404467300002, title = {Metallic phases from disordered (2+1)-dimensional quantum electrodynamics}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {23}, year = {2017}, month = {JUN 26}, pages = {235145}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Metallic phases have been observed in several disordered two-dimensional (2D) systems, including thin films near superconductor-insulator transitions and quantum Hall systems near plateau transitions. The existence of 2D metallic phases at zero temperature generally requires an interplay of disorder and interaction effects. Consequently, experimental observations of 2D metallic behavior have largely defied explanation. We formulate a general stability criterion for strongly interacting, massless Dirac fermions against disorder, which describe metallic ground states with vanishing density of states. We show that (2+1)-dimensional quantum electrodynamics (QED(3)) with a large, even number of fermion flavors remains metallic in the presence of weak scalar potential disorder due to the dynamic screening of disorder by gauge fluctuations. We also show that QED3 with weak mass disorder exhibits a stable, dirty metallic phase in which both interactions and disorder play important roles.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.235145}, author = {Goswami, Pallab and Goldman, Hart and Raghu, S.} } @article { ISI:000406382800003, title = {Methods, analysis, and the treatment of systematic errors for the electron electric dipole moment search in thorium monoxide}, journal = {NEW JOURNAL OF PHYSICS}, volume = {19}, year = {2017}, month = {JUL 25}, issn = {1367-2630}, doi = {10.1088/1367-2630/aa708e}, author = {Baron, J. and Campbell, W. C. and DeMille, D. and Doyle, J. M. and Gabrielse, G. and Gurevich, Y. V. and Hess, P. W. and Hutzler, N. R. and Kirilov, E. and Kozyryev, I. and O{\textquoteright}Leary, B. R. and Panda, C. D. and Parsons, M. F. and Spaun, B. and Vutha, A. C. and West, A. D. and West, E. P. and ACME Collaboration} } @article { ISI:000407549100005, title = {Mobility edges in one-dimensional bichromatic incommensurate potentials}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {8}, year = {2017}, month = {AUG 14}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.085119}, author = {Li, Xiao and Li, Xiaopeng and S. Das Sarma} } @article {6496, title = {Modal interference in optical nanofibers for sub-Angstrom radius sensitivity}, journal = {Optica}, volume = {4}, year = {2017}, month = {Jan}, pages = {157{\textendash}162}, abstract = {Optical nanofibers (ONFs) of sub-wavelength dimensions confine light in modes with a strong evanescent field that can trap, probe, and manipulate nearby quantum systems. To measure the evanescent field and propagating modes and to optimize ONF performance, a surface probe is desirable during fabrication. We demonstrate a nondestructive near-field measurement of light propagation in ONFs by sampling the local evanescent field with a microfiber. This approach reveals the behavior of all propagating modes, and because the modal beat lengths in cylindrical waveguides depend strongly on the radius, it simultaneously provides exquisite sensitivity to the ONF radius. We show that our measured spatial frequencies provide a map of the average ONF radius (over a 600\&\#x00A0;\&\#x03BC;m window) along the 10\&\#x00A0;mm ONF waist with a 40\&\#x00A0;pm resolution and a high signal-to-noise ratio. The measurements agree with scanning electron microscopy (SEM) to within SEM instrument resolutions. This fast method is immune to polarization, intrinsic birefringence, mechanical vibrations, and scattered light and provides a set of constraints to protect from systematic errors in the measurements.

}, keywords = {Fiber characterization, Fiber optics, Nanophotonics and photonic crystals}, doi = {https://doi.org/10.1364/OPTICA.4.000157}, url = {http://www.osapublishing.org/optica/abstract.cfm?URI=optica-4-1-157}, author = {Fredrik K. Fatemi and Jonathan E. Hoffman and Pablo Solano and Eliot F. Fenton and Guy Beadie and Steven L. Rolston and Luis A. Orozco} } @article {ISI:000400050700001, title = {Multicritical behavior in dissipative Ising models}, journal = {PHYSICAL REVIEW A}, volume = {95}, number = {4}, year = {2017}, month = {APR 26}, abstract = {We analyze theoretically the many-body dynamics of a dissipative Ising model in a transverse field using a variational approach. We find that the steady-state phase diagram is substantially modified compared to its equilibrium counterpart, including the appearance of a multicritical point belonging to a different universality class. Building on our variational analysis, we establish a field-theoretical treatment corresponding to a dissipative variant of a Ginzburg-Landau theory, which allows us to compute the upper critical dimension of the system. Finally, we present a possible experimental realization of the dissipative Ising model using ultracold Rydberg gases.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.95.042133}, author = {Overbeck, Vincent R. and Maghrebi, Mohammad F. and Gorshkov, Alexey V. and Weimer, Hendrik} } @article {7296, title = {Multispecies Trapped-Ion Node for Quantum Networking}, journal = {Phys. Rev. Lett.}, volume = {118}, year = {2017}, month = {Jun}, pages = {250502}, doi = {10.1103/PhysRevLett.118.250502}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.118.250502}, author = {Inlek, I. V. and Crocker, C. and Lichtman, M. and Sosnova, K. and Monroe, C.} } @article { ISI:000413927000009, title = {Non-thermalization in trapped atomic ion spin chains}, journal = {PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES}, volume = {375}, number = {2108}, year = {2017}, month = {DEC 13}, issn = {1364-503X}, doi = {10.1098/rsta.2017.0107}, author = {Hess, P. W. and Becker, P. and Kaplan, H. B. and Kyprianidis, A. and Lee, A. C. and Neyenhuis, B. and Pagano, G. and Richerme, P. and Senko, C. and Smith, J. and Tan, W. L. and Zhang, J. and Monroe, C.} } @article {6701, title = {Observation of a discrete time crystal}, journal = {Nature}, volume = {543}, year = {2017}, month = {03/2017}, pages = {217-220}, chapter = {217}, keywords = {ions, many-body localization, time crystal}, doi = {10.1038/nature21413}, author = {J Zhang and P W. Hess and A Kyprianidis and P Becker and A Lee and J Smith and G Pagano and I.-D Potirniche and A C. Potter and A Vishwanath and N Y. Yao and C Monroe} } @article {7821, title = {Observation of a many-body dynamical phase transition with a 53-qubit quantum simulator}, journal = {Nature}, volume = {551}, year = {2017}, chapter = {601}, author = {J Zhang and G Pagano and P. W. Hess and A Kyprianidis and P. Becker and H. Kaplan and A. V. Gorshkov and Gong, Z-X and Christopher Monroe} } @article {ISI:000395052200001, title = {Observation of optomechanical buckling transitions}, journal = {NATURE COMMUNICATIONS}, volume = {8}, year = {2017}, month = {MAR 1}, pages = {14481}, abstract = {Correlated phases of matter provide long-term stability for systems as diverse as solids, magnets and potential exotic quantum materials. Mechanical systems, such as buckling transition spring switches, can have engineered, stable configurations whose dependence on a control variable is reminiscent of non-equilibrium phase transitions. In hybrid optomechanical systems, light and matter are strongly coupled, allowing engineering of rapid changes in the force landscape, storing and processing information, and ultimately probing and controlling behaviour at the quantum level. Here we report the observation of first-and second-order buckling transitions between stable mechanical states in an optomechanical system, in which full control of the nature of the transition is obtained by means of the laser power and detuning. The underlying multiwell confining potential we create is highly tunable, with a sub-nanometre distance between potential wells. Our results enable new applications in photonics and information technology, and may enable explorations of quantum phase transitions and macroscopic quantum tunnelling in mechanical systems.}, issn = {2041-1723}, doi = {10.1038/ncomms14481}, author = {Xu, H. and Kemiktarak, U. and Fan, J. and Ragole, S. and Lawall, J. and Taylor, J. M.} } @article {7481, title = {Observation of prethermalization in long-range interacting spin chains}, journal = {Science Advances}, volume = {3}, year = {2017}, abstract = {Although statistical mechanics describes thermal equilibrium states, these states may or may not emerge dynamically for a subsystem of an isolated quantum many-body system. For instance, quantum systems that are near-integrable usually fail to thermalize in an experimentally realistic time scale, and instead relax to quasi-stationary prethermal states that can be described by statistical mechanics, when approximately conserved quantities are included in a generalized Gibbs ensemble (GGE). We experimentally study the relaxation dynamics of a chain of up to 22 spins evolving under a long-range transverse-field Ising Hamiltonian following a sudden quench. For sufficiently long-range interactions, the system relaxes to a new type of prethermal state that retains a strong memory of the initial conditions. However, the prethermal state in this case cannot be described by a standard GGE; it rather arises from an emergent double-well potential felt by the spin excitations. This result shows that prethermalization occurs in a broader context than previously thought, and reveals new challenges for a generic understanding of the thermalization of quantum systems, particularly in the presence of long-range interactions.

}, doi = {10.1126/sciadv.1700672}, url = {http://advances.sciencemag.org/content/3/8/e1700672}, author = {Neyenhuis, Brian and Zhang, Jiehang and Hess, Paul W. and Smith, Jacob and Lee, Aaron C. and Richerme, Phil and Gong, Zhe-Xuan and Gorshkov, Alexey V. and Monroe, Christopher} } @article {ISI:000403271700004, title = {Observation of Topological Links Associated with Hopf Insulators in a Solid-State Quantum Simulator}, journal = {CHINESE PHYSICS LETTERS}, volume = {34}, number = {6}, year = {2017}, month = {JUN}, pages = {060302}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {Hopf insulators are intriguing three-dimensional topological insulators characterized by an integer topological invariant. They originate from the mathematical theory of Hopf fibration and epitomize the deep connection between knot theory and topological phases of matter, which distinguishes them from other classes of topological insulators. Here, we implement a model Hamiltonian for Hopf insulators in a solid-state quantum simulator and report the first experimental observation of their topological properties, including nontrivial topological links associated with the Hopf fibration and the integer-valued topological invariant obtained from a direct tomographic measurement. Our observation of topological links and Hopf fibration in a quantum simulator opens the door to probe rich topological properties of Hopf insulators in experiments. The quantum simulation and probing methods are also applicable to the study of other intricate three-dimensional topological model Hamiltonians.}, \%\%Address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}, issn = {0256-307X}, doi = {10.1088/0256-307X/34/6/060302}, author = {Yuan, X. -X. and He, L. and Wang, S. -T. and Deng, D. -L. and Wang, F. and Lian, W. -Q. and Wang, X. and Zhang, C. -H. and Zhang, H. -L. and Chang, X. -Y. and Duan, L. -M.} } @inbook {7621, title = {Optical Nanofibers: A New Platform for Quantum Optics}, booktitle = {Advances In Atomic, Molecular, and Optical Physics}, volume = {66}, year = {2017}, pages = {439}, chapter = {7}, author = {Pablo Solano and Grover, J. A. and Jonathan E Hoffman and Sylvain Ravets and Fredrik K Fatemi and Luis A Orozco and Steven L Rolston} } @article {ISI:000404461300009, title = {Optimal phase measurements with bright- and vacuum-seeded SU(1,1) interferometers}, journal = {PHYSICAL REVIEW A}, volume = {95}, number = {6}, year = {2017}, month = {JUN 27}, pages = {063843}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The SU(1,1) interferometer can be thought of as a Mach-Zehnder interferometer with its linear beam splitters replaced with parametric nonlinear optical processes. We consider the cases of bright- and vacuum-seeded SU(1,1) interferometers using intensity or homodyne detectors. A simplified truncated scheme with only one nonlinear interaction is introduced, which not only beats conventional intensity detection with a bright seed, but can saturate the phase-sensitivity bound set by the quantum Fisher information. We also show that the truncated scheme achieves a sub-shot-noise phase sensitivity in the vacuum-seeded case, despite the phase-sensing optical beams having no well-defined phase.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9926}, doi = {10.1103/PhysRevA.95.063843}, author = {Anderson, Brian E. and Schmittberger, Bonnie L. and Gupta, Prasoon and Jones, Kevin M. and Lett, Paul D.} } @article { ISI:000411527100054, title = {Optomechanical Analogy for Toy Cosmology with Quantized Scale Factor}, journal = {ENTROPY}, volume = {19}, number = {9}, year = {2017}, month = {SEP}, issn = {1099-4300}, doi = {10.3390/e19090485}, author = {Smiga, Joseph A. and Taylor, Jacob M.} } @article { ISI:000406093300012, title = {Phase sensing beyond the standard quantum limit with a variation on the SU(1,1) interferometer}, journal = {OPTICA}, volume = {4}, number = {7}, year = {2017}, month = {JUL 20}, pages = {752-756}, issn = {2334-2536}, doi = {10.1364/OPTICA.4.000752}, author = {Anderson, Brian E. and Gupta, Prasoon and Schmittberger, Bonnie L. and Horrom, Travis and Hermann-Avigliano, Carla and Jones, Kevin M. and Lett, Paul D.} } @article { ISI:000408619600008, title = {Phenomenology of the soft gap, zero-bias peak, and zero-mode splitting in ideal Majorana nanowires}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {5}, year = {2017}, month = {AUG 30}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.054520}, author = {Liu, Chun-Xiao and Setiawan, F. and Sau, Jay D. and S. Das Sarma} } @article { ISI:000416312900008, title = {Probing the dielectric response of the interfacial buffer layer in epitaxial graphene via optical spectroscopy}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {19}, year = {2017}, month = {NOV 28}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.195437}, author = {Hill, Heather M. and Rigosi, Albert F. and Chowdhury, Sugata and Yang, Yanfei and Nguyen, Nhan V. and Tavazza, Francesca and Elmquist, Randolph E. and Newell, David B. and Walker, Angela R. Hight} } @article { ISI:000405697200005, title = {Proximity-induced low-energy renormalization in hybrid semiconductor-superconductor Majorana structures}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {1}, year = {2017}, month = {JUL 17}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.014510}, author = {Stanescu, Tudor D. and S. Das Sarma} } @article {7271, title = {Quantum correlations from a room-temperature optomechanical cavity}, journal = {Science}, volume = {356}, year = {2017}, pages = {1265{\textendash}1268}, abstract = {Quantum back action{\textemdash}the {\textquotedblleft}reaction{\textquotedblright} of a quantum mechanical object to being measured{\textemdash}is normally observed at cryogenic temperatures, where it is easier to distinguish from thermal motion. Purdy et al. managed to tease out the effects of quantum back action at room temperature by using a mechanical oscillator and probing it with light (see the Perspective by Harris). The fluctuations of the force produced by the light probe caused correlated changes to the motion of the oscillator and the properties of the transmitted light. These correlations revealed the effects of the back action, which allows the system to be used as a quantum thermometer.Science, this issue p. 1265; see also p. 1232The act of position measurement alters the motion of an object being measured. This quantum measurement backaction is typically much smaller than the thermal motion of a room-temperature object and thus difficult to observe. By shining laser light through a nanomechanical beam, we measure the beam{\textquoteright}s thermally driven vibrations and perturb its motion with optical force fluctuations at a level dictated by the Heisenberg measurement-disturbance uncertainty relation. We demonstrate a cross-correlation technique to distinguish optically driven motion from thermally driven motion, observing this quantum backaction signature up to room temperature. We use the scale of the quantum correlations, which is determined by fundamental constants, to gauge the size of thermal motion, demonstrating a path toward absolute thermometry with quantum mechanically calibrated ticks.

}, issn = {0036-8075}, doi = {10.1126/science.aag1407}, url = {http://science.sciencemag.org/content/356/6344/1265}, author = {Purdy, T. P. and Grutter, K. E. and Srinivasan, K. and Taylor, J. M.} } @article {ISI:000401235900001, title = {Quantum Entanglement in Neural Network States}, journal = {PHYSICAL REVIEW X}, volume = {7}, number = {2}, year = {2017}, month = {MAY 11}, abstract = {Machine learning, one of today{\textquoteright}s most rapidly growing interdisciplinary fields, promises an unprecedented perspective for solving intricate quantum many-body problems. Understanding the physical aspects of the representative artificial neural-network states has recently become highly desirable in the applications of machine-learning techniques to quantum many-body physics. In this paper, we explore the data structures that encode the physical features in the network states by studying the quantum entanglement properties, with a focus on the restricted-Boltzmann-machine (RBM) architecture. We prove that the entanglement entropy of all short-range RBM states satisfies an area law for arbitrary dimensions and bipartition geometry. For long-range RBM states, we show by using an exact construction that such states could exhibit volume-law entanglement, implying a notable capability of RBM in representing quantum states with massive entanglement. Strikingly, the neural-network representation for these states is remarkably efficient, in the sense that the number of nonzero parameters scales only linearly with the system size. We further examine the entanglement properties of generic RBM states by randomly sampling the weight parameters of the RBM. We find that their averaged entanglement entropy obeys volume-law scaling, and the meantime strongly deviates from the Page entropy of the completely random pure states. We show that their entanglement spectrum has no universal part associated with random matrix theory and bears a Poisson-type level statistics. Using reinforcement learning, we demonstrate that RBM is capable of finding the ground state (with power-law entanglement) of a model Hamiltonian with a long-range interaction. In addition, we show, through a concrete example of the one-dimensional symmetry-protected topological cluster states, that the RBM representation may also be used as a tool to analytically compute the entanglement spectrum. Our results uncover the unparalleled power of artificial neural networks in representing quantum many-body states regardless of how much entanglement they possess, which paves a novel way to bridge computer-science-based machine-learning techniques to outstanding quantum condensed-matter physics problems.}, issn = {2160-3308}, doi = {10.1103/PhysRevX.7.021021}, author = {Deng, Dong-Ling and Li, Xiaopeng and S. Das Sarma} } @article {ISI:000396518400037, title = {Quantum frequency bridge: high-accuracy characterization of a nearly-noiseless parametric frequency converter}, journal = {OPTICS EXPRESS}, volume = {25}, number = {2}, year = {2017}, month = {JAN 23}, pages = {907-917}, abstract = {We demonstrate an efficient and inherently ultra-low noise frequency conversion via a parametric sum frequency generation. Due to the wide separation between the input and pump frequencies and the low pump frequency relative to the input photons, the upconversion results in only approximate to 100 background photons per hour. To measure such a low rate, we introduced a dark count reduction algorithm for an optical transition edge sensor. (C) 2017 Optical Society of America}, issn = {1094-4087}, doi = {10.1364/OE.25.000907}, author = {Burenkov, Ivan A. and Gerrits, Thomas and Lita, Adriana and Nam, Sae Woo and Shalm, L. Krister and Polyakov, Sergey V.} } @article {ISI:000418652100002, title = {Quantum phases of two-component bosons with spin-orbit coupling in optical lattices}, journal = {PHYSICAL REVIEW A}, volume = {96}, number = {6}, year = {2017}, month = {DEC 26}, pages = {061603}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Ultracold bosons in optical lattices are one of the few systems where bosonic matter is known to exhibit strong correlations. Here we push the frontier of our understanding of interacting bosons in optical lattices by adding synthetic spin-orbit coupling, and show that new kinds of density and chiral orders develop. The competition between the optical lattice period and the spin-orbit coupling length-which can be made comparable in experiments-along with the spin hybridization induced by a transverse field (i.e., Rabi coupling) and interparticle interactions create a rich variety of quantum phases including uniform, nonuniform, and phase-separated superfluids, as well as Mott insulators. The spontaneous symmetry-breaking phenomena at the transitions between them are explained by a two-order-parameter Ginzburg-Landau model with multiparticle umklapp processes. Finally, in order to characterize each phase, we calculated their experimentally measurable crystal momentum distributions.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9926}, doi = {10.1103/PhysRevA.96.061603}, author = {Yamamoto, Daisuke and Ian B Spielman and de Melo, C. A. R. Sa} } @article {ISI:000418786600007, title = {Quantum Redirection of Antenna Absorption to Photosynthetic Reaction Centers}, journal = {JOURNAL OF PHYSICAL CHEMISTRY LETTERS}, volume = {8}, number = {24}, year = {2017}, month = {DEC 21}, pages = {6015-6021}, publisher = {AMER CHEMICAL SOC}, type = {Article}, abstract = {The early steps of photosynthesis involve the photoexcitation of reaction centers (RCs) and light-harvesting (LH) units. Here, we show that the historically overlooked excitonic delocalization across RC and LH pigments results in a redistribution of absorption amplitudes that benefits the absorption cross section of the optical bands associated with the RC of several species. While we prove that this redistribution is robust to the microscopic details of the dephasing between these units in the purple bacterium Rhodospirillum rubrum, we are able to show that the redistribution witnesses a more fragile, but persistent, coherent population dynamics which directs excitations from the LH toward the RC units under incoherent illumination and physiological conditions. Even though the redirection does not seem to affect importantly the overall efficiency in photosynthesis, stochastic optimization allows us to delineate clear guidelines and develop simple analytic expressions in order to amplify the coherent redirection in artificial nanostructures.}, \%\%Address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, issn = {1948-7185}, doi = {10.1021/acs.jpclett.7b02714}, author = {Caycedo-Soler, Felipe and Schroeder, Christopher A. and Autenrieth, Caroline and Pick, Arne and Ghosh, Robin and Huelga, Susana F. and Plenio, Martin B.} } @article {7376, title = {Quantum simulation of a Fermi{\textendash}Hubbard model using a semiconductor quantum dot array}, journal = {Nature}, volume = {548}, year = {2017}, month = {08/2017}, pages = {70{\textendash}73}, isbn = {0028-0836}, url = {http://dx.doi.org/10.1038/nature23022}, author = {Hensgens, T and Fujita, T and Janssen, L and Li, Xiao and Van Diepen, C J. and Reichl, C and Wegscheider, W and S. Das Sarma and Vandersypen, L M. K.} } @article {ISI:000401585800006, title = {Realizing quantum advantage without entanglement in single-photon states}, journal = {NEW JOURNAL OF PHYSICS}, volume = {19}, year = {2017}, month = {MAY 16}, pages = {053009}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {We propose an optical circuit for attaining quantum measurement advantage in a system that has no quantum entanglement. Our device produces symmetric two-qubit X-states with controllable anti-diagonal elements, and does not require entangled states as input. We discuss the use of this device in a two-qubit quantum game. When entanglement is absent, the maximum quantum advantage in this game is 1/3 bit. A slightly diminished quantum advantage, 0.311 bit, can be realized with a simplified transaction protocol.}, \%\%Address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}, keywords = {encoding process, entanglement, quantum advantage, quantum discord, single photons, X-states}, issn = {1367-2630}, doi = {10.1088/1367-2630/aa6cf4}, author = {Maldonado-Trapp, A. and Solano, Pablo and Hu, Anzi and Clark, Charles W.} } @article { ISI:000404365400001, title = {Resilience of the quantum Rabi model in circuit QED}, journal = {JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL}, volume = {50}, number = {29}, year = {2017}, month = {JUL 21}, issn = {1751-8113}, doi = {10.1088/1751-8121/aa6fbc}, author = {Manucharyan, Vladimir E. and Baksic, Alexandre and Ciuti, Cristiano} } @article { ISI:000406262000010, title = {A room temperature continuous-wave nanolaser using colloidal quantum wells}, journal = {NATURE COMMUNICATIONS}, volume = {8}, year = {2017}, month = {JUL 26}, issn = {2041-1723}, doi = {10.1038/s41467-017-00198-z}, author = {Yang, Zhili and Pelton, Matthew and Fedin, Igor and Talapin, Dmitri V. and Waks, Edo} } @article { ISI:000411973900008, title = {Rydberg optical Feshbach resonances in cold gases}, journal = {PHYSICAL REVIEW A}, volume = {96}, number = {3}, year = {2017}, month = {SEP 28}, issn = {2469-9926}, doi = {10.1103/PhysRevA.96.032719}, author = {Sandor, Nora and Gonzalez-Ferez, Rosario and Julienne, Paul S. and Pupillo, Guido} } @article { ISI:000415173000002, title = {Simultaneous, Full Characterization of a Single-Photon State}, journal = {PHYSICAL REVIEW X}, volume = {7}, number = {4}, year = {2017}, month = {NOV 15}, issn = {2160-3308}, doi = {10.1103/PhysRevX.7.041036}, author = {Thomay, Tim and Polyakov, Sergey V. and Gazzano, Olivier and Goldschmidt, Elizabeth and Eldredge, Zachary D. and Huber, Tobias and Loo, Vivien and Solomon, Glenn S.} } @article {ISI:000402467200001, title = {Single-particle excitations in disordered Weyl fluids}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {23}, year = {2017}, month = {JUN 1}, pages = {235101}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We theoretically study the single-particle Green function of a three-dimensional disordered Weyl semimetal using a combination of techniques. These include analytic T-matrix and renormalization group methods with complementary regimes of validity and an exact numerical approach based on the kernel polynomial technique. We show that at any nonzero disorder, Weyl excitations are not ballistic: They instead have a nonzero linewidth that for weak short-range disorder arises from nonperturbative resonant impurity scattering. Perturbative approaches find a quantum critical point between a semimetal and a metal at a finite disorder strength, but this transition is avoided due to nonperturbative effects. At moderate disorder strength and intermediate energies the avoided quantum critical point renormalizes the scaling of single-particle properties. In this regime we compute numerically the anomalous dimension of the fermion field and find eta = 0.13 +/- 0.04, which agrees well with a renormalization group analysis (eta = 0.125). Our predictions can be directly tested by ARPES and STM measurements in samples dominated by neutral impurities.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.235101}, author = {Pixley, J. H. and Chou, Yang-Zhi and Goswami, Pallab and Huse, David A. and Nandkishore, Rahul and Radzihovsky, Leo and S. Das Sarma} } @article { ISI:000408826800004, title = {Skyrmion defects and competing singlet orders in a half-filled antiferromagnetic Kondo-Heisenberg model on the honeycomb lattice}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {12}, year = {2017}, month = {SEP 1}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.125101}, author = {Liu, Chia-Chuan and Goswami, Pallab and Si, Qimiao} } @article { ISI:000414424700002, title = {Solvable Family of Driven-Dissipative Many-Body Systems}, journal = {PHYSICAL REVIEW LETTERS}, volume = {119}, number = {19}, year = {2017}, month = {NOV 6}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.119.190402}, author = {Foss-Feig, Michael and Young, Jeremy T. and Albert, Victor V. and Gorshkov, Alexey V. and Maghrebi, Mohammad F.} } @article { ISI:000411572100009, title = {Spin-orbit coupling induced two-electron relaxation in silicon donor pairs}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {11}, year = {2017}, month = {SEP 25}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.115444}, author = {Song, Yang and S. Das Sarma} } @article { ISI:000414951500015, title = {Spontaneous avalanche dephasing in large Rydberg ensembles}, journal = {PHYSICAL REVIEW A}, volume = {96}, number = {5}, year = {2017}, month = {NOV 13}, issn = {2469-9926}, doi = {10.1103/PhysRevA.96.053409}, author = {Boulier, T. and Magnan, E. and Bracamontes, C. and Maslek, J. and Goldschmidt, E. A. and Young, J. T. and Gorshkov, A. V. and Rolston, S. L. and Porto, J. V.} } @article { ISI:000415315500001, title = {Stability of fractional quantum Hall states in disordered photonic systems}, journal = {NEW JOURNAL OF PHYSICS}, volume = {19}, year = {2017}, month = {NOV 14}, issn = {1367-2630}, doi = {10.1088/1367-2630/aa89a5}, author = {DeGottardi, Wade and Hafezi, Mohammad} } @article {7776, title = {State-to-state chemistry for three-body recombination in an ultracold rubidium gas}, journal = {Science}, volume = {358}, year = {2017}, pages = {921{\textendash}924}, abstract = {Crossed molecular beams have provided decades{\textquoteright} worth of knowledge into how quantum mechanics governs chemical reactivity. Nonetheless, the technique is generally limited to the collision of two partners. Wolf et al. report on a three-body process with full quantum state resolution. By cooling rubidium atoms to ultralow temperatures in an optical trap, they were able to observe dimer formation, stabilized by collision with a third atom, and extract the precise dependence of product states on the initial states of the atoms involved.Science, this issue p. 921Experimental investigation of chemical reactions with full quantum state resolution for all reactants and products has been a long-term challenge. Here we prepare an ultracold few-body quantum state of reactants and demonstrate state-to-state chemistry for the recombination of three spin-polarized ultracold rubidium (Rb) atoms to form a weakly bound Rb2 molecule. The measured product distribution covers about 90\% of the final products, and we are able to discriminate between product states with a level splitting as small as 20 megahertz multiplied by Planck{\textquoteright}s constant. Furthermore, we formulate propensity rules for the distribution of products, and we develop a theoretical model that predicts many of our experimental observations. The scheme can readily be adapted to other species and opens a door to detailed investigations of inelastic or reactive processes.

}, issn = {0036-8075}, doi = {10.1126/science.aan8721}, url = {http://science.sciencemag.org/content/358/6365/921}, author = {Wolf, Joschka and Dei{\ss}, Markus and Kr{\"u}kow, Artjom and Tiemann, Eberhard and Ruzic, Brandon P. and Wang, Yujun and D{\textquoteright}Incao, Jos{\'e} P. and Julienne, Paul S. and Denschlag, Johannes Hecker} } @article {ISI:000400371800001, title = {Statistical bubble localization with random interactions}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {2}, year = {2017}, month = {JAN 24}, abstract = {We study one-dimensional spinless fermions with random interactions, but without any on-site disorder. We find that random interactions generically stabilize a many-body localized phase, in spite of the completely extended single-particle degrees of freedom. In the large randomness limit, we construct {\textquoteleft}{\textquoteleft}bubble-neck{{\textquoteright}{\textquoteright}} eigenstates having a universal area-law entanglement entropy on average, with the number of volume-law states being exponentially suppressed. We argue that this statistical localization is beyond the phenomenological local-integrals-of-motion description of many-body localization. With exact diagonalization, we confirm the robustness of the many-body localized phase at finite randomness by investigating eigenstate properties such as level statistics, entanglement/participation entropies, and nonergodic quantum dynamics. At weak random interactions, the system develops a thermalization transition when the single-particle hopping becomes dominant.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.020201}, author = {Li, Xiaopeng and Deng, Dong-Ling and Wu, Yang-Le and S. Das Sarma} } @article { ISI:000411880800029, title = {Storing light in a tiny box A cavity containing rare-earth atoms in a glass stores light pulses for quantum memories}, journal = {SCIENCE}, volume = {357}, number = {6358}, year = {2017}, month = {SEP 29}, pages = {1354-1355}, issn = {0036-8075}, doi = {10.1126/science.aao2437}, author = {Waks, Edo and Goldschmidt, Elizabeth A.} } @article { ISI:000413442100006, title = {Strong-coupling phases of the spin-orbit-coupled spin-1 Bose-Hubbard chain: Odd-integer Mott lobes and helical magnetic phases}, journal = {PHYSICAL REVIEW A}, volume = {96}, number = {4}, year = {2017}, month = {OCT 23}, issn = {2469-9926}, doi = {10.1103/PhysRevA.96.043622}, author = {Pixley, J. H. and Cole, William S. and Ian B Spielman and Rizzi, Matteo and S. Das Sarma} } @article {7871, title = {Super-radiance reveals infinite-range dipole interactions through a nanofiber}, journal = {Nature Communications}, volume = {8}, year = {2017}, pages = {1857}, abstract = {Atoms interact with each other through the electromagnetic field, creating collective states that can radiate faster or slower than a single atom, i.e., super- and sub-radiance. When the field is confined to one dimension it enables infinite-range atom{\textendash}atom interactions. Here we present the first report of infinite-range interactions between macroscopically separated atomic dipoles mediated by an optical waveguide. We use cold 87Rb atoms in the vicinity of a single-mode optical nanofiber (ONF) that coherently exchange evanescently coupled photons through the ONF mode. In particular, we observe super-radiance of a few atoms separated by hundreds of resonant wavelengths. The same platform allows us to measure sub-radiance, a rarely observed effect, presenting a unique tool for quantum optics. This result constitutes a proof of principle for collective behavior of macroscopically delocalized atomic states, a crucial element for new proposals in quantum information and many-body physics.

}, issn = {2041-1723}, doi = {10.1038/s41467-017-01994-3}, url = {https://doi.org/10.1038/s41467-017-01994-3}, author = {Solano, P and Barberis-Blostein, P and Fatemi, F K and Orozco, L A and Rolston, S L} } @article {ISI:000394086900002, title = {Superuniversality of topological quantum phase transition and global phase diagram of dirty topological systems in three dimensions}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {7}, year = {2017}, month = {FEB 16}, pages = {075131}, abstract = {The quantum phase transition between two clean, noninteracting topologically distinct gapped states in three dimensions is governed by a massless Dirac fermion fixed point, irrespective of the underlying symmetry class, and this constitutes a remarkably simple example of superuniversality. For a sufficiently weak disorder strength, we show that the massless Dirac fixed point is at the heart of the robustness of superuniversality. We establish this by considering both perturbative and nonperturbative effects of disorder. The superuniversality breaks down at a critical strength of disorder, beyond which the topologically distinct localized phases become separated by a delocalized diffusive phase. In the global phase diagram, the disorder controlled fixed point where superuniversality is lost, serves as a multicritical point, where the delocalized diffusive and two topologically distinct localized phases meet and the nature of the localization-delocalization transition depends on the underlying symmetry class. Based on these features, we construct the global phase diagrams of noninteracting, dirty topological systems in three dimensions. We also establish a similar structure of the phase diagram and the superuniversality for weak disorder in higher spatial dimensions. By noting that 1/r(2) power-law correlated disorder acts as a marginal perturbation for massless Dirac fermions in any spatial dimension d, we have established a general renormalization group framework for addressing disorder driven critical phenomena for fixed spatial dimension d > 2.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.075131}, author = {Goswami, Pallab and Chakravarty, Sudip} } @article {7146, title = {Surface-dominated conduction up to 240K in the Kondo insulator SmB6 under strain}, journal = {Nature Materials}, volume = {advance online publication}, year = {2017}, month = {04/2017}, pages = {{\textendash}}, isbn = {1476-4660}, url = {http://dx.doi.org/10.1038/nmat4888}, author = {Stern, A. and Dzero, M. and Galitski, V. M. and Fisk, Z. and Xia, J.} } @article {ISI:000394654700001, title = {Temperature-induced decay of persistent currents in a superfluid ultracold gas}, journal = {PHYSICAL REVIEW A}, volume = {95}, number = {2}, year = {2017}, month = {FEB 24}, pages = {021602}, abstract = {We study how temperature affects the lifetime of a quantized, persistent current state in a toroidal Bose-Einstein condensate. When the temperature is increased, we find a decrease in the persistent current lifetime. Comparing our measured decay rates to simple models of thermal activation and quantum tunneling, we do not find agreement. We also measured the size of the hysteresis loops in our superfluid ring as a function of temperature, enabling us to extract the critical velocity. The measured critical velocity is found to depend strongly on temperature, approaching the zero-temperature mean-field solution as the temperature is decreased. This indicates that an appropriate definition of critical velocity must incorporate the role of thermal fluctuations, something not explicitly contained in traditional theories.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.95.021602}, author = {Kumar, A. and Eckel, S. and Jendrzejewski, F. and Campbell, G. K.} } @article { ISI:000412247200006, title = {Temporal and spectral manipulations of correlated photons using a time lens}, journal = {PHYSICAL REVIEW A}, volume = {96}, number = {4}, year = {2017}, month = {OCT 4}, issn = {2469-9926}, doi = {10.1103/PhysRevA.96.043807}, author = {Mittal, Sunil and Orre, Venkata Vikram and Restelli, Alessandro and Salem, Reza and Goldschmidt, Elizabeth A. and Hafezi, Mohammad} } @article { ISI:000405362900007, title = {Theoretical study of the g factor and lifetime of the 6s6 p P-3(0) state of mercury}, journal = {PHYSICAL REVIEW A}, volume = {96}, number = {1}, year = {2017}, month = {JUL 13}, issn = {2469-9926}, doi = {10.1103/PhysRevA.96.012509}, author = {Porsev, S. G. and Safronova, U. I. and Safronova, M. S.} } @article {ISI:000394660600014, title = {Theory of interaction-induced renormalization of Drude weight and plasmon frequency in chiral multilayer graphene}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {8}, year = {2017}, month = {FEB 21}, abstract = {We develop a theory for the optical conductivity of doped ABC-stacked multilayer graphene including the effects of electron-electron interactions. Applying the quantum kinetic formalism, we formulate a set of pseudospin Bloch equations that govern the dynamics of the nonequilibrium density matrix driven by an external ac electric field under the influence of Coulomb interactions. These equations reveal a dynamical mechanism that couples theDrude and interband responses arising from the chirality of pseudospin textures in multilayer graphene systems. We demonstrate that this results in an interaction-induced enhancement of the Drude weight and plasmon frequency strongly dependent on the pseudospin winding number. Using bilayer graphene as an example, we also study the influence of higher-energy bands and find that they contribute considerable renormalization effects not captured by a low-energy two-band description. We argue that this enhancement of Drude weight and plasmon frequency occurs generally in materials characterized by electronic chirality.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.085428}, author = {Li, Xiao and Tse, Wang-Kong} } @article { ISI:000414954400003, title = {Thermodynamic limits for optomechanical systems with conservative potentials}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {18}, year = {2017}, month = {NOV 13}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.184106}, author = {Ragole, Stephen and Xu, Haitan and Lawall, John and Taylor, Jacob M.} } @article { ISI:000408705200026, title = {Threshold Dynamics of a Semiconductor Single Atom Maser}, journal = {PHYSICAL REVIEW LETTERS}, volume = {119}, number = {9}, year = {2017}, month = {AUG 31}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.119.097702}, author = {Liu, Y. -Y. and Stehlik, J. and Eichler, C. and Mi, X. and Hartke, T. R. and Gullans, M. J. and Taylor, J. M. and Petta, J. R.} } @article {7261, title = {Time-reversal symmetry-breaking superconductivity in epitaxial bismuth/nickel bilayers}, journal = {Science Advances}, volume = {3}, year = {2017}, abstract = {Superconductivity that spontaneously breaks time-reversal symmetry (TRS) has been found, so far, only in a handful of three-dimensional (3D) crystals with bulk inversion symmetry. We report an observation of spontaneous TRS breaking in a 2D superconducting system without inversion symmetry: the epitaxial bilayer films of bismuth and nickel. The evidence comes from the onset of the polar Kerr effect at the superconducting transition in the absence of an external magnetic field, detected by the ultrasensitive loop-less fiber-optic Sagnac interferometer. Because of strong spin-orbit interaction and lack of inversion symmetry in a Bi/Ni bilayer, superconducting pairing cannot be classified as singlet or triplet. We propose a theoretical model where magnetic fluctuations in Ni induce the superconducting pairing of the orbital symmetry between the electrons in Bi. In this model, the order parameter spontaneously breaks the TRS and has a nonzero phase winding number around the Fermi surface, thus making it a rare example of a 2D topological superconductor.

}, doi = {10.1126/sciadv.1602579}, url = {http://advances.sciencemag.org/content/3/3/e1602579}, author = {Gong, Xinxin and Kargarian, Mehdi and Stern, Alex and Yue, Di and Zhou, Hexin and Jin, Xiaofeng and Galitski, Victor M. and Yakovenko, Victor M. and Xia, Jing} } @article {ISI:000396271900006, title = {Topological spin ordering via Chern-Simons superconductivity}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {9}, year = {2017}, month = {MAR 15}, pages = {094511}, abstract = {We use the Chern-Simons (CS) fermion representation of s = 1/2 spin operators to construct topological, long-range magnetically ordered states of interacting two-dimensional (2D) quantum spin models. We show that the fermion-fermion interactions mediated by the dynamic CS flux attachment may give rise to Cooper pairing of the fermions. Specifically, in an XY model on the honeycomb lattice, this construction leads to a {\textquoteleft}{\textquoteleft}CS superconductor{{\textquoteright}{\textquoteright}}, which belongs to a topologically nontrivial in 2D symmetry class DIII, with particle-hole and time-reversal symmetries. It is shown that in the original spin language, this state corresponds to a symmetry protected topological state, which coexists with a magnetic long-range order. We discuss physical manifestations of the topological character of the corresponding state.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.094511}, author = {Sedrakyan, Tigran A. and Galitski, Victor M. and Kamenev, Alex} } @article {ISI:000401997600008, title = {Transport in superconductor-normal metal-superconductor tunneling structures: Spinful p-wave and spin-orbit-coupled topological wires}, journal = {PHYSICAL REVIEW B}, volume = {95}, number = {17}, year = {2017}, month = {MAY 22}, pages = {174515}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We theoretically study transport properties of voltage-biased one-dimensional superconductor-normal metal-superconductor tunnel junctions with arbitrary junction transparency where the superconductors can have trivial or nontrivial topology. Motivated by recent experimental efforts on Majorana properties of superconductor-semiconductor hybrid systems, we consider two explicit models for topological superconductors: (i) spinful p-wave, and (ii) spin-split spin-orbit-coupled s-wave. We provide a comprehensive analysis of the zero-temperature dc current I and differential conductance dI/dV of voltage-biased junctions with or without Majorana zero modes (MZMs). The presence of an MZM necessarily gives rise to two tunneling conductance peaks at voltages eV = +/-Delta(lead), i.e., the voltage at which the superconducting gap edge of the lead aligns with the MZM. We find that the MZM conductance peak probed by a superconducting lead without a BCS singularity has a nonuniversal value, which decreases with decreasing junction transparency. This is in contrast to the MZM tunneling conductance measured by a superconducting lead with a BCS singularity, where the conductance peak in the tunneling limit takes the quantized value GM = (4 - pi)2e(2)/h independent of the junction transparency. We also discuss the {\textquoteleft}{\textquoteleft}subharmonic gap structure{{\textquoteright}{\textquoteright}}, a consequence of multiple Andreev reflections, in the presence and absence of MZMs. Finally, we show that for finite-energy Andreev bound states (ABSs), the conductance peaks shift away from the gap bias voltage eV = +/-Delta(lead) to a larger value set by the ABSs energy. Our work should have important implications for the extensive current experimental efforts toward creating topological superconductivity and MZMs in semiconductor nanowires proximity coupled to ordinary s-wave superconductors.}, \%\%Address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA

}, issn = {2469-9950}, doi = {10.1103/PhysRevB.95.174515}, author = {Setiawan, F. and Cole, William S. and Sau, Jay D. and S. Das Sarma} } @article { ISI:000411162600002, title = {Transport properties across the many-body localization transition in quasiperiodic and random systems}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {10}, year = {2017}, month = {SEP 19}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.104205}, author = {Setiawan, F. and Deng, Dong-Ling and Pixley, J. H.} } @article {7641, title = {Ultrafast creation of large Schr{\"o}dinger cat states of an atom}, journal = {Nature Communications}, volume = {8}, year = {2017}, pages = {697}, abstract = {Mesoscopic quantum superpositions, or Schr{\"o}dinger cat states, are widely studied for fundamental investigations of quantum measurement and decoherence as well as applications in sensing and quantum information science. The generation and maintenance of such states relies upon a balance between efficient external coherent control of the system and sufficient isolation from the environment. Here we create a variety of cat states of a single trapped atom{\textquoteright}s motion in a harmonic oscillator using ultrafast laser pulses. These pulses produce high fidelity impulsive forces that separate the atom into widely separated positions, without restrictions that typically limit the speed of the interaction or the size and complexity of the resulting motional superposition. This allows us to quickly generate and measure cat states larger than previously achieved in a harmonic oscillator, and create complex multi-component superposition states in atoms.

}, isbn = {2041-1723}, doi = {10.1038/s41467-017-00682-6}, url = {https://doi.org/10.1038/s41467-017-00682-6}, author = {Johnson, K. G. and Wong-Campos, J. D. and Neyenhuis, B. and Mizrahi, J. and Monroe, C.} } @article { ISI:000414956700009, title = {Valley blockade in a silicon double quantum dot}, journal = {PHYSICAL REVIEW B}, volume = {96}, number = {20}, year = {2017}, month = {NOV 13}, issn = {2469-9950}, doi = {10.1103/PhysRevB.96.205302}, author = {Perron, Justin K. and Gullans, Michael J. and Taylor, Jacob M. and Stewart, Jr., M. D. and Zimmerman, Neil M.} } @article { ISI:000411773400029, title = {Visible spectra of highly charged holmium ions observed with a compact electron beam ion trap}, journal = {NUCLEAR INSTRUMENTS \& METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS}, volume = {408}, year = {2017}, note = {18th International Conference on the Physics of Highly Charged Ions (HCI), Jan Kochanowski Univ, Kielce, POLAND, SEP 11-16, 2016}, month = {OCT 1}, pages = {118-121}, issn = {0168-583X}, doi = {10.1016/j.nimb.2017.03.135}, author = {Nakajima, Takayuki and Okada, Kunihiro and Wada, Michiharu and Dzuba, Vladimir A. and Safronova, Marianna S. and Safronova, Ulyana I. and Ohmae, Noriaki and Katori, Hidetoshi and Nakamura, Nobuyuki} } @article { ISI:000415687200020, title = {Z(3) Parafermionic Zero Modes without Andreev Backscattering from the 2/3 Fractional Quantum Hall State}, journal = {PHYSICAL REVIEW LETTERS}, volume = {119}, number = {21}, year = {2017}, month = {NOV 20}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.119.217701}, author = {Alavirad, Yahya and Clarke, David and Nag, Amit and Sau, Jay D.} } @article {ISI:000379187600030, title = {Active stabilization of ion trap radiofrequency potentials}, journal = {REVIEW OF SCIENTIFIC INSTRUMENTS}, volume = {87}, number = {5}, year = {2016}, month = {JUN}, pages = {053110}, issn = {0034-6748}, doi = {10.1063/1.4948734}, author = {Johnson, K. G. and Wong-Campos, J. D. and Restelli, A. and Landsman, K. A. and Neyenhuis, B. and Mizrahi, J. and Monroe, C.} } @article { ISI:000381478800008, title = {Amperean Pairing at the Surface of Topological Insulators}, journal = {PHYSICAL REVIEW LETTERS}, volume = {117}, number = {7}, year = {2016}, month = {AUG 12}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.117.076806}, author = {Kargarian, Mehdi and Efimkin, Dmitry K. and Galitski, Victor} } @article {4380, title = {Anomalous broadening in driven dissipative Rydberg systems}, journal = {Phys. Rev. Lett.}, volume = {116}, year = {2016}, month = {03/2016}, pages = {113001}, abstract = {We observe interaction-induced broadening of the two-photon 5s-18s transition in 87Rb atoms trapped in a 3D optical lattice. The measured linewidth increases by nearly two orders of magnitude with increasing atomic density and excitation strength, with corresponding suppression of resonant scattering and enhancement of off-resonant scattering. We attribute the increased linewidth to resonant dipole-dipole interactions of 18s atoms with blackbody induced population in nearby np states. Over a range of initial atomic densities and excitation strengths, the transition width is described by a single function of the steady-state density of Rydberg atoms, and the observed resonant excitation rate corresponds to that of a two-level system with the measured, rather than natural, linewidth. The broadening mechanism observed here is likely to have negative implications for many proposals with coherently interacting Rydberg atoms.

}, doi = {10.1103/PhysRevLett.116.113001}, author = {Goldschmidt, E A and Boulier, T and Brown, R C and Koller, S B and Young, J T and Gorshkov, A V and Rolston, S L and Porto, J V} } @article { ISI:000369337200015, title = {Anomalous Coulomb Drag in Electron-Hole Bilayers due to the Formation of Excitons}, journal = {PHYSICAL REVIEW LETTERS}, volume = {116}, number = {4}, year = {2016}, month = {JAN 26}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.116.046801}, author = {Efimkin, Dmitry K. and Galitski, Victor} } @article { ISI:000368473600004, title = {Anomalous supersolidity in a weakly interacting dipolar Bose mixture on a square lattice}, journal = {PHYSICAL REVIEW A}, volume = {93}, number = {1}, year = {2016}, month = {JAN 19}, issn = {1050-2947}, doi = {10.1103/PhysRevA.93.011605}, author = {Wilson, Ryan M. and Shirley, Wilbur E. and Natu, Stefan S.} } @article { ISI:000380586600042, title = {Are the surface Fermi arcs in Dirac semimetals topologically protected?}, journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, volume = {113}, number = {31}, year = {2016}, month = {AUG 2}, pages = {8648-8652}, issn = {0027-8424}, doi = {10.1073/pnas.1524787113}, author = {Kargarian, Mehdi and Randeria, Mohit and Lu, Yuan-Ming} } @article { ISI:000375984800011, title = {Beliaev damping in quasi-two-dimensional dipolar condensates}, journal = {PHYSICAL REVIEW A}, volume = {93}, number = {5}, year = {2016}, month = {MAY 9}, issn = {2469-9926}, doi = {10.1103/PhysRevA.93.053606}, author = {Wilson, Ryan M. and Natu, Stefan} } @article { ISI:000376250800005, title = {Ca3P2 and other topological semimetals with line nodes and drumhead surface states}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {20}, year = {2016}, month = {MAY 17}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.205132}, author = {Chan, Y. -H. and Chiu, Ching-Kai and Chou, M. Y. and Schnyder, Andreas P.} } @article { ISI:000371398000004, title = {Calculation for polar Kerr effect in high-temperature cuprate superconductors}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {7}, year = {2016}, month = {FEB 29}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.075156}, author = {Sharma, Girish and Tewari, Sumanta and Goswami, Pallab and Yakovenko, Victor M. and Chakravarty, Sudip} } @article {ISI:000372413300003, title = {Causality and quantum criticality in long-range lattice models}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {12}, year = {2016}, month = {MAR 17}, pages = {125128}, chapter = {125128}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.125128}, author = {Maghrebi, Mohammad F. and Gong, Zhe-Xuan and Foss-Feig, Michael and Gorshkov, Alexey V.} } @article {ISI:000372407200003, title = {Characterization of the local charge environment of a single quantum dot via resonance fluorescence}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {11}, year = {2016}, month = {MAR 14}, pages = {115307}, chapter = {115307}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.115307}, author = {Chen, Disheng and Lander, Gary R. and Krowpman, Kyle S. and Solomon, Glenn S. and Flagg, Edward B.} } @article { ISI:000382008100013, title = {Charge 2e/3 Superconductivity and Topological Degeneracies without Localized Zero Modes in Bilayer Fractional Quantum Hall States}, journal = {PHYSICAL REVIEW LETTERS}, volume = {117}, number = {9}, year = {2016}, month = {AUG 24}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.117.096803}, author = {Barkeshli, Maissam} } @article { ISI:000383053400001, title = {Classification of topological quantum matter with symmetries}, journal = {REVIEWS OF MODERN PHYSICS}, volume = {88}, number = {3}, year = {2016}, month = {AUG 31}, issn = {0034-6861}, doi = {10.1103/RevModPhys.88.035005}, author = {Chiu, Ching-Kai and Teo, Jeffrey C. Y. and Schnyder, Andreas P. and Ryu, Shinsei} } @article {ISI:000392283300002, title = {Co-designing a scalable quantum computer with trapped atomic ions}, journal = {NPJ QUANTUM INFORMATION}, volume = {2}, year = {2016}, month = {NOV 8}, pages = {16034}, abstract = {The first generation of quantum computers are on the horizon, fabricated from quantum hardware platforms that may soon be able to tackle certain tasks that cannot be performed or modelled with conventional computers. These quantum devices will not likely be universal or fully programmable, but special-purpose processors whose hardware will be tightly co-designed with particular target applications. Trapped atomic ions are a leading platform for first-generation quantum computers, but they are also fundamentally scalable to more powerful general purpose devices in future generations. This is because trapped ion qubits are atomic clock standards that can be made identical to a part in 1015, and their quantum circuit connectivity can be reconfigured through the use of external fields, without modifying the arrangement or architecture of the qubits themselves. In this forwardlooking overview, we show how a modular quantum computer with thousands or more qubits can be engineered from ion crystals, and how the linkage between ion trap qubits might be tailored to a variety of applications and quantum-computing protocols.}, issn = {2056-6387}, doi = {10.1038/npjqi.2016.34}, author = {Brown, Kenneth R. and Kim, Jungsang and Monroe, Christopher} } @article { ISI:000375997500002, title = {Coherence and degree of time-bin entanglement from quantum dots}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {20}, year = {2016}, month = {MAY 12}, pages = {201301}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.201301}, author = {Huber, Tobias and Ostermann, Laurin and Prilmueller, Maximilian and Solomon, Glenn S. and Ritsch, Helmut and Weihs, Gregor and Predojevic, Ana} } @article {ISI:000382794600007, title = {Collective phases of strongly interacting cavity photons}, journal = {PHYSICAL REVIEW A}, volume = {94}, number = {3}, year = {2016}, month = {SEP 1}, pages = {033801}, issn = {2469-9926}, doi = {10.1103/PhysRevA.94.033801}, author = {Wilson, Ryan M. and Mahmud, Khan W. and Hu, Anzi and Gorshkov, Alexey V. and Hafezi, Mohammad and Foss-Feig, Michael} } @article { ISI:000377497200003, title = {Competing ground states of strongly correlated bosons in the Harper-Hofstadter-Mott model}, journal = {PHYSICAL REVIEW A}, volume = {93}, number = {6}, year = {2016}, month = {JUN 10}, pages = {063610}, issn = {2469-9926}, doi = {10.1103/PhysRevA.93.063610}, author = {Natu, Stefan S. and Mueller, Erich J. and S. Das Sarma} } @article {ISI:000377796500006, title = {Contact resistance and phase slips in mesoscopic superfluid-atom transport}, journal = {PHYSICAL REVIEW A}, volume = {93}, number = {6}, year = {2016}, month = {JUN 15}, pages = {063619}, issn = {2469-9926}, doi = {10.1103/PhysRevA.93.063619}, author = {Eckel, S. and Lee, Jeffrey G. and Jendrzejewski, F. and Lobb, C. J. and Campbell, G. K. and Hill, III, W. T.} } @article { ISI:000378910200001, title = {Continuous and discontinuous topological quantum phase transitions}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {4}, year = {2016}, month = {JUL 1}, pages = {041101}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.041101}, author = {Roy, Bitan and Goswami, Pallab and Sau, Jay D.} } @article {4682, title = {Demonstration of a small programmable quantum computer with atomic qubits}, journal = {Nature}, volume = {536}, year = {2016}, month = {08/2016}, pages = {63-66}, doi = {10.1038/nature18648}, url = {http://www.nature.com/nature/journal/v536/n7614/full/nature18648.html}, author = {Debnath, S and Linke, N M and Figgatt, C and Landsman, K A and Wright, K and Monroe, C} } @article { ISI:000382794800002, title = {Detecting pi-phase superfluids with p-wave symmetry in a quasi-one-dimensional optical lattice}, journal = {PHYSICAL REVIEW A}, volume = {94}, number = {3}, year = {2016}, month = {SEP 2}, issn = {2469-9926}, doi = {10.1103/PhysRevA.94.031602}, author = {Liu, Bo and Li, Xiaopeng and Hulet, Randall G. and Liu, W. Vincent} } @article { ISI:000376250800002, title = {Dirty Weyl semimetals: Stability, phase transition, and quantum criticality}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {20}, year = {2016}, month = {MAY 17}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.201302}, author = {Bera, Soumya and Sau, Jay D. and Roy, Bitan} } @article {ISI:000369402400006, title = {Disorder-driven itinerant quantum criticality of three-dimensional massless Dirac fermions}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {8}, year = {2016}, month = {FEB 1}, pages = {085103}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.085103}, author = {Pixley, J. H. and Goswami, Pallab and S. Das Sarma} } @article {4424, title = {Doublon dynamics and polar molecule production in an optical lattice}, journal = {Nature Communications}, volume = {7}, year = {2016}, month = {04/2016}, pages = {11279}, doi = {10.1038/ncomms11279}, author = {Covey, Jacob P and Moses, Stephen A and G{\"a}rttner, Martin and Safavi-Naini, Arghavan and Miecnikowski, Matthew T and Fu, Zhengkun and Schachenmayer, Johannes and Julienne, Paul S and Rey, Ana M. and Jin, Deborah S and Ye, Jun} } @article { ISI:000372799400003, title = {Drumhead surface states and topological nodal-line fermions in TlTaSe2}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {12}, year = {2016}, month = {MAR 28}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.121113}, author = {Bian, Guang and Chang, Tay-Rong and Zheng, Hao and Velury, Saavanth and Xu, Su-Yang and Neupert, Titus and Chiu, Ching-Kai and Huang, Shin-Ming and Sanchez, Daniel S. and Belopolski, Ilya and Alidoust, Nasser and Chen, Peng-Jen and Chang, Guoqing and Bansil, Arun and Jeng, Horng-Tay and Lin, Hsin and Hasan, M. Zahid} } @article { ISI:000381399500005, title = {Dynamical many-body localization in an integrable model}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {8}, year = {2016}, month = {AUG 11}, pages = {085120}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.085120}, author = {Keser, Aydin Cem and Ganeshan, Sriram and Refael, Gil and Galitski, Victor} } @article { ISI:000368290900012, title = {Dynamics of an ion coupled to a parametric superconducting circuit}, journal = {PHYSICAL REVIEW A}, volume = {93}, number = {1}, year = {2016}, month = {JAN 14}, pages = {013412}, issn = {1050-2947}, doi = {10.1103/PhysRevA.93.013412}, author = {Kafri, Dvir and Adhikari, Prabin and Taylor, Jacob M.} } @article { ISI:000381485200004, title = {Dynamics of two coupled semiconductor spin qubits in a noisy environment}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {4}, year = {2016}, month = {JUL 27}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.045435}, author = {S. Das Sarma and Throckmorton, Robert E. and Wu, Yang-Le} } @article {ISI:000385227100098, title = {Effect of input phase modulation to a phase-sensitive optical amplifier}, journal = {OPTICS EXPRESS}, volume = {24}, number = {17}, year = {2016}, month = {AUG 22}, pages = {19871-19880}, issn = {1094-4087}, doi = {10.1364/OE.24.019871}, author = {Li, Tian and Anderson, Brian E. and Horrom, Travis and Jones, Kevin M. and Lett, Paul D.} } @article {ISI:000383248700006, title = {Effective Field Theory for Rydberg Polaritons}, journal = {PHYSICAL REVIEW LETTERS}, volume = {117}, number = {11}, year = {2016}, month = {SEP 6}, pages = {113601}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.117.113601}, author = {Gullans, M. J. and Thompson, J. D. and Wang, Y. and Liang, Q. -Y. and Vuletic, V. and Lukin, M. D. and Gorshkov, A. V.} } @article { ISI:000368483600011, title = {Effects of nonequilibrium quasiparticles in a thin-film superconducting microwave resonator under optical illumination}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {2}, year = {2016}, month = {JAN 19}, pages = {024514}, issn = {1098-0121}, doi = {10.1103/PhysRevB.93.024514}, author = {Budoyo, R. P. and Hertzberg, J. B. and Ballard, C. J. and Voigt, K. D. and Kim, Z. and Anderson, J. R. and Lobb, C. J. and Wellstood, F. C.} } @article {6261, title = {Effects of photo-neutralization on the emission properties of quantum dots}, journal = {Opt. Express}, volume = {24}, year = {2016}, month = {Sep}, pages = {21794{\textendash}21801}, abstract = {In this paper we investigate the coherence properties of a quantum dot used as photon pair source, under two-photon resonant excitation in combination with an additional photo-neutralization laser. The photo-neutralization increases the efficiency of the excitation process and thus, the brightness of the source, by a factor of approximately 1.5 for biexciton-exciton pairs. This enhancement does not degrade the relevant coherences in the system; neither the single photon coherence time, nor the coherence of the excitation process.

}, keywords = {-wire and -dot devices, and noise, Fluctuations, Quantum optics, Quantum-well, relaxations}, doi = {10.1364/OE.24.021794}, url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-24-19-21794}, author = {Tobias Huber and Ana Predojevi{\'c} and Glenn S. Solomon and Gregor Weihs} } @article { ISI:000375331200002, title = {Emergent Lorentz symmetry near fermionic quantum critical points in two and three dimensions}, journal = {JOURNAL OF HIGH ENERGY PHYSICS}, number = {4}, year = {2016}, month = {APR 5}, issn = {1029-8479}, doi = {10.1007/JHEP04(2016)018}, author = {Roy, Bitan and Juricic, Vladimir and Herbut, Igor F.} } @article {ISI:000385239800002, title = {Engineering large Stark shifts for control of individual clock state qubits}, journal = {PHYSICAL REVIEW A}, volume = {94}, number = {4}, year = {2016}, month = {OCT 7}, pages = {042308}, issn = {2469-9926}, doi = {10.1103/PhysRevA.94.042308}, author = {Lee, A. C. and Smith, J. and Richerme, P. and Neyenhuis, B. and Hess, P. W. and Zhang, J. and Monroe, C.} } @article { ISI:000380952800001, title = {Enigmatic 12/5 fractional quantum Hall effect}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {7}, year = {2016}, month = {AUG 4}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.075108}, author = {Pakrouski, Kiryl and Troyer, Matthias and Wu, Yang-Le and S. Das Sarma and Peterson, Michael R.} } @article { ISI:000379647900004, title = {Fast control of semiconductor qubits beyond the rotating-wave approximation}, journal = {PHYSICAL REVIEW A}, volume = {94}, number = {1}, year = {2016}, month = {JUL 14}, issn = {2469-9926}, doi = {10.1103/PhysRevA.94.012321}, author = {Song, Yang and Kestner, J. P. and Wang, Xin and S. Das Sarma} } @article { ISI:000372413000004, title = {Filter function formalism beyond pure dephasing and non-Markovian noise in singlet-triplet qubits}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {12}, year = {2016}, month = {MAR 16}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.121407}, author = {Barnes, Edwin and Rudner, Mark S. and Martins, Frederico and Malinowski, Filip K. and Marcus, Charles M. and Kuemmeth, Ferdinand} } @article {ISI:000369217400001, title = {Flight of a heavy particle nonlinearly coupled to a quantum bath}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {1}, year = {2016}, month = {JAN 28}, pages = {014309}, abstract = {Fluctuation and dissipation are byproducts of coupling to the {\textquoteleft}{\textquoteleft}environment.{{\textquoteright}{\textquoteright}} The Caldeira-Leggett model, a successful paradigm of quantum Brownian motion, views the environment as a collection of harmonic oscillators linearly coupled to the system. However, symmetry considerations may forbid a linear coupling, e.g., for a neutral particle in quantum electrodynamics. We argue that the absence of linear couplings can lead to a fundamentally different behavior. Specifically, we consider a heavy particle quadratically coupled to quantum fluctuations of the bath. In one dimension the particle undergoes anomalous diffusion, unfolding as a power-law distribution in space, reminiscent of Levy flights. We suggest condensed matter analogs where similar effects may arise.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.014309}, author = {Maghrebi, Mohammad F. and Krueger, Matthias and Kardar, Mehran} } @article { ISI:000369727700005, title = {Formalism for the solution of quadratic Hamiltonians with large cosine terms}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {7}, year = {2016}, month = {FEB 8}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.075118}, author = {Ganeshan, Sriram and Levin, Michael} } @article {4468, title = {Geometrical Pumping with a Bose-Einstein Condensate}, journal = {Phys. Rev. Lett.}, volume = {116}, year = {2016}, month = {05/2016}, pages = {200402}, abstract = {We realized a quantum geometric {\textquotedblleft}charge{\textquotedblright} pump for a Bose-Einstein condensate (BEC) in the lowest Bloch band of a novel bipartite magnetic lattice. Topological charge pumps in filled bands yield quantized pumping set by the global{\textemdash}topological{\textemdash}properties of the bands. In contrast, our geometric charge pump for a BEC occupying just a single crystal momentum state exhibits nonquantized charge pumping set by local{\textemdash}geometrical{\textemdash}properties of the band structure. Like topological charge pumps, for each pump cycle we observed an overall displacement (here, not quantized) and a temporal modulation of the atomic wave packet{\textquoteright}s position in each unit cell, i.e., the polarization.

}, doi = {10.1103/PhysRevLett.116.200402}, url = {http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.200402}, author = {Lu, H and Schemmer, M and Aycock, L M and Genkina, D and Sugawa, S and Ian B Spielman} } @article { ISI:000373760500009, title = {Half vortex and fractional electrical charge in two dimensions}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {15}, year = {2016}, month = {APR 11}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.155415}, author = {Roy, Bitan and Herbut, Igor F.} } @article {ISI:000382800500015, title = {High-resolution adaptive imaging of a single atom}, journal = {NATURE PHOTONICS}, volume = {10}, number = {9}, year = {2016}, month = {SEP}, pages = {606-610}, issn = {1749-4885}, author = {Wong-Campos, J. D. and Johnson, K. G. and Neyenhuis, B. and Mizrahi, J. and Monroe, C.} } @article {6241, title = {Holography with a neutron interferometer}, journal = {Opt. Express}, volume = {24}, year = {2016}, month = {Oct}, pages = {22528{\textendash}22535}, abstract = {We use a Mach-Zehnder interferometer to perform neutron holography of a spiral phase plate. The object beam passes through a spiral phase plate, acquiring the phase twist characteristic of orbital angular momentum states. The reference beam passes through a fused silica prism, acquiring a linear phase gradient. The resulting hologram is a fork dislocation image, which could be used to reconstruct neutron beams with various orbital angular momenta. This work paves the way for novel applications of neutron holography, diffraction and imaging.

}, keywords = {Digital holography, Interferometry, Optical vortices, Propagation}, doi = {10.1364/OE.24.022528}, url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-24-20-22528}, author = {Dusan Sarenac and Michael G. Huber and Benjamin Heacock and Muhammad Arif and Charles W. Clark and David G. Cory and Chandra B. Shahi and Dmitry A. Pushin} } @article { ISI:000380100300003, title = {How to infer non-Abelian statistics and topological visibility from tunneling conductance properties of realistic Majorana nanowires}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {3}, year = {2016}, month = {JUL 20}, pages = {035143}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.035143}, author = {S. Das Sarma and Nag, Amit and Sau, Jay D.} } @article { ISI:000383235000012, title = {Induced spectral gap and pairing correlations from superconducting proximity effect}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {12}, year = {2016}, month = {SEP 6}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.125304}, author = {Chiu, Ching-Kai and Cole, William S. and S. Das Sarma} } @article {6361, title = {Interacting Atomic Interferometry for Rotation Sensing Approaching the Heisenberg Limit}, journal = {Phys. Rev. Lett.}, volume = {117}, year = {2016}, month = {Nov}, pages = {203002}, doi = {10.1103/PhysRevLett.117.203002}, url = {http://link.aps.org/doi/10.1103/PhysRevLett.117.203002}, author = {Ragole, Stephen and Taylor, Jacob M.} } @article {ISI:000369402400001, title = {Interaction-driven exotic quantum phases in spin-orbit-coupled spin-1 bosons}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {8}, year = {2016}, month = {FEB 1}, pages = {081101}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.081101}, author = {Pixley, J. H. and Natu, Stefan S. and Ian B Spielman and S. Das Sarma} } @article { ISI:000373117500001, title = {Interplanar coupling-dependent magnetoresistivity in high-purity layered metals}, journal = {NATURE COMMUNICATIONS}, volume = {7}, year = {2016}, month = {MAR}, issn = {2041-1723}, doi = {10.1038/ncomms10903}, author = {Kikugawa, N. and Goswami, P. and Kiswandhi, A. and Choi, E. S. and Graf, D. and Baumbach, R. E. and Brooks, J. S. and Sugii, K. and Iida, Y. and Nishio, M. and Uji, S. and Terashima, T. and Rourke, P. M. C. and Hussey, N. E. and Takatsu, H. and Yonezawa, S. and Maeno, Y. and Balicas, L.} } @article {ISI:000399139100002, title = {Interrupted orbital motion in density-wave systems}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {20}, year = {2016}, month = {NOV 2}, abstract = {In conventional metals, electronic transport in a magnetic field is characterized by the motion of electrons along orbits on the Fermi surface, which usually causes an increase in the resistivity through averaging over velocities. Here, we show that large deviations from this behavior can arise in density-wave systems close to their ordering temperature. Specifically, enhanced scattering off collective fluctuations can lead to a change of direction of the orbital motion on reconstructed pockets. In weak magnetic fields, this leads to linear magnetoconductivity, the sign of which depends on the electric-field direction. At a critical magnetic field, the conductivity crosses zero for certain directions, signifying a thermodynamic instability of the density-wave state.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.205103}, author = {Breitkreiz, Maxim and Brydon, P. M. R. and Timm, Carsten} } @article { ISI:000375997100002, title = {Kaleidoscope of quantum phases in a long-range interacting spin-1 chain}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {20}, year = {2016}, month = {MAY 11}, pages = {205115}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.205115}, author = {Gong, Z. -X. and Maghrebi, M. F. and Hu, A. and Foss-Feig, M. and Richerme, P. and Monroe, C. and Gorshkov, A. V.} } @article {ISI:000386099300008, title = {Landauer formulation of photon transport in driven systems}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {15}, year = {2016}, month = {OCT 20}, pages = {155437}, abstract = {Understanding the behavior of light in nonequilibrium scenarios underpins much of quantum optics and optical physics. While lasers provide a severe example of a nonequilibrium problem, recent interests in the near-equilibrium physics of so-called photon gases, such as in Bose condensation of light or in attempts to make photonic quantum simulators, suggest one re-examine some near-equilibrium cases. Here we consider how a sinusoidal parametric coupling between two semi-infinite photonic transmission lines leads to the creation and flow of photons between the two lines. Our approach provides a photonic analog to the Landauer transport formula, and using nonequilbrium Green{\textquoteright}s functions, we can extend it to the case of an interacting region between two photonic leads where the sinusoid frequency plays the role of a voltage bias. Crucially, we identify both the mathematical framework and the physical regime in which photonic transport is directly analogous to electronic transport and regimes in which other behavior such as two-mode squeezing can emerge.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.155437}, author = {Wang, Chiao-Hsuan and Taylor, Jacob M.} } @article {ISI:000379697900007, title = {Magic wavelengths, matrix elements, polarizabilities, and lifetimes of Cs}, journal = {PHYSICAL REVIEW A}, volume = {94}, number = {1}, year = {2016}, month = {JUL 6}, pages = {012505}, abstract = {Motivated by recent interest in their applications, we report a systematic study of Cs atomic properties calculated by a high-precision relativistic all-order method. Excitation energies, reduced matrix elements, transition rates, and lifetimes are determined for levels with principal quantum numbers n <= 12 and orbital angular momentum quantum numbers l <= 3. Recommended values and estimates of uncertainties are provided for a number of electric-dipole transitions and the electric dipole polarizabilities of the ns, np, and nd states. We also report a calculation of the electric quadrupole polarizability of the ground state. We display the dynamic polarizabilities of the 6s and 7p states for optical wavelengths between 1160 and 1800 nm and identify corresponding magic wavelengths for the 6s - 7p(1/2) and 6s - 7p(3/2) transitions. The values of relevant matrix elements needed for polarizability calculations at other wavelengths are provided.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.94.012505}, author = {Safronova, M. S. and Safronova, U. I. and Clark, Charles W.} } @article {4390, title = {Magnetic phases of spin-1 spin{\textendash}orbit-coupled Bose gases}, journal = {Nature Communications}, volume = {7}, year = {2016}, month = {03/2016}, pages = {10897}, abstract = {Phases of matter are characterized by order parameters describing the type and degree of order in a system. Here we experimentally explore the magnetic phases present in a near-zero temperature spin-1 spin{\textendash}orbit-coupled atomic Bose gas and the quantum phase transitions between these phases. We observe ferromagnetic and unpolarized phases, which are stabilized by spin{\textendash}orbit coupling{\textquoteright}s explicit locking between spin and motion. These phases are separated by a critical curve containing both first- and second-order transitions joined at a tricritical point. The first-order transition, with observed width as small as h {\texttimes} 4\ Hz, gives rise to long-lived metastable states. These measurements are all in agreement with theory.

}, doi = {10.1038/ncomms10897}, author = {Daniel L Campbell and Ryan M. Price and Andika Putra and Ana Vald{\'e}s-Curiel and Dimitrios Trypogeorgos and Ian B Spielman} } @article { ISI:000379648400004, title = {Majorana spintronics}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {1}, year = {2016}, month = {JUL 14}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.014511}, author = {Liu, Xin and Li, Xiaopeng and Deng, Dong-Ling and Liu, Xiong-Jun and S. Das Sarma} } @article {ISI:000385514800001, title = {Many-body decoherence dynamics and optimized operation of a single-photon switch}, journal = {NEW JOURNAL OF PHYSICS}, volume = {18}, year = {2016}, month = {SEP 13}, pages = {092001}, abstract = {Wedevelop a theoretical framework to characterize the decoherence dynamics due to multi-photon scattering in an all-optical switch based on Rydberg atom induced nonlinearities. By incorporating the knowledge of this decoherence process into optimal photon storage and retrieval strategies, we establish optimized switching protocols for experimentally relevant conditions, and evaluate the corresponding limits in the achievable fidelities. Based on these results we work out a simplified description that reproduces recent experiments (Nat. Commun. 7 12480) and provides a new interpretation in terms of many-body decoherence involving multiple incident photons and multiple gate excitations forming the switch. Aside from offering insights into the operational capacity of realistic photon switching capabilities, our work provides a complete description of spin wave decoherence in a Rydberg quantum optics setting, and has immediate relevance to a number of further applications employing photon storage in Rydberg media.}, issn = {1367-2630}, doi = {10.1088/1367-2630/18/9/092001}, author = {Murray, C. R. and Gorshkov, A. V. and Pohl, T.} } @article {4632, title = {Many-body localization in a quantum simulator with programmable random disorder}, journal = {Nature Physics}, year = {2016}, month = {06/2016}, doi = {10.1038/nphys3783}, url = {http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3783.html}, author = {Smith, J and Lee, A and Richerme, P and Neyenhuis, B and Hess, P W and Hauke, P and Heyl, M and Huse, D A and Monroe, C} } @article {ISI:000390255800002, title = {Measurement of many-body chaos using a quantum clock}, journal = {PHYSICAL REVIEW A}, volume = {94}, number = {6}, year = {2016}, month = {DEC 22}, pages = {062329}, abstract = {There has been recent progress in understanding chaotic features in many-body quantum systems. Motivated by the scrambling of information in black holes, it has been suggested that the time dependence of out-of-time-ordered (OTO) correlation functions such as < O-2(t)O-1(0)O-2(t)O-1(0)> is a faithful measure of quantum chaos. Experimentally, these correlators are challenging to access since they apparently require access to both forward and backward time evolution with the system Hamiltonian. Here we propose a protocol to measure such OTO correlators using an ancilla that controls the direction of time. Specifically, by coupling the state of the ancilla to the system Hamiltonian of interest, we can emulate the forward and backward time propagation, where the ancilla plays the role of a quantum clock. Within this scheme, the continuous evolution of the entire system (the system of interest and the ancilla) is governed by a time-independent Hamiltonian. We discuss the implementation of our protocol with current circuit-QED technology for a class of interacting Hamiltonians. Our protocol is immune to errors that could occur when the direction of time evolution is externally controlled by a classical switch.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.94.062329}, author = {Zhu, Guanyu and Hafezi, Mohammad and Grover, Tarun} } @article {4175, title = {Measurement of Topological Invariants in a 2D Photonic System}, journal = {Nature Photonics}, volume = {10}, year = {2016}, month = {02/2016}, pages = {180}, doi = {10.1038/nphoton.2016.10}, url = {http://www.nature.com/nphoton/journal/v10/n3/full/nphoton.2016.10.html}, author = {S Mittal and Ganeshan, S and Jingyun Fan and A Vaezi and Mohammad Hafezi} } @article {ISI:000388280000002, title = {Measurement Protocol for the Entanglement Spectrum of Cold Atoms}, journal = {PHYSICAL REVIEW X}, volume = {6}, number = {4}, year = {2016}, month = {NOV 17}, pages = {041033}, abstract = {Entanglement, and, in particular, the entanglement spectrum, plays a major role in characterizing many-body quantum systems. While there has been a surge of theoretical works on the subject, no experimental measurement has been performed to date because of the lack of an implementable measurement scheme. Here, we propose a measurement protocol to access the entanglement spectrum of many-body states in experiments with cold atoms in optical lattices. Our scheme effectively performs a Ramsey spectroscopy of the entanglement Hamiltonian and is based on the ability to produce several copies of the state under investigation, together with the possibility to perform a global swap gate between two copies conditioned on the state of an auxiliary qubit. We show how the required conditional swap gate can be implemented with cold atoms, either by using Rydberg interactions or coupling the atoms to a cavity mode. We illustrate these ideas on a simple (extended) Bose-Hubbard model where such a measurement protocol reveals topological features of the Haldane phase.}, issn = {2160-3308}, doi = {10.1103/PhysRevX.6.041033}, author = {Pichler, Hannes and Zhu, Guanyu and Seif, Alireza and Zoller, Peter and Hafezi, Mohammad} } @article {ISI:000372462400001, title = {Minimally destructive, Doppler measurement of a quantized flow in a ring-shaped Bose-Einstein condensate}, journal = {NEW JOURNAL OF PHYSICS}, volume = {18}, year = {2016}, month = {FEB 1}, pages = {025001}, issn = {1367-2630}, doi = {10.1088/1367-2630/18/2/025001}, author = {Kumar, A. and Anderson, N. and Phillips, W. D. and Eckel, S. and Campbell, G. K. and Stringari, S.} } @article { ISI:000367162300001, title = {Multi-channel entanglement distribution using spatial multiplexing from four-wave mixing in atomic vapor}, journal = {JOURNAL OF MODERN OPTICS}, volume = {63}, number = {3}, year = {2016}, pages = {185-189}, issn = {0950-0340}, doi = {10.1080/09500340.2015.1071891}, author = {Gupta, Prasoon and Horrom, Travis and Anderson, Brian E. and Glasser, Ryan and Lett, Paul D.} } @article {ISI:000383412100015, title = {Nanostructure-Induced Distortion in Single-Emitter Microscopy}, journal = {NANO LETTERS}, volume = {16}, number = {9}, year = {2016}, month = {SEP}, pages = {5415-5419}, issn = {1530-6984}, doi = {10.1021/acs.nanolett.6b01708}, author = {Lim, Kangmook and Ropp, Chad and Barik, Sabyasachi and Fourkas, John and Shapiro, Benjamin and Waks, Edo} } @article { ISI:000368295000003, title = {Nernst and magnetothermal conductivity in a lattice model of Weyl fermions}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {3}, year = {2016}, month = {JAN 13}, issn = {1098-0121}, doi = {10.1103/PhysRevB.93.035116}, author = {Sharma, Girish and Goswami, Pallab and Tewari, Sumanta} } @article { ISI:000372432300003, title = {Noise Suppression Using Symmetric Exchange Gates in Spin Qubits}, journal = {PHYSICAL REVIEW LETTERS}, volume = {116}, number = {11}, year = {2016}, month = {MAR 16}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.116.116801}, author = {Martins, Frederico and Malinowski, Filip K. and Nissen, Peter D. and Barnes, Edwin and Fallahi, Saeed and Gardner, Geoffrey C. and Manfra, Michael J. and Marcus, Charles M. and Kuemmeth, Ferdinand} } @article { ISI:000370245900009, title = {Noise-induced collective quantum state preservation in spin qubit arrays}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {8}, year = {2016}, month = {FEB 16}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.085420}, author = {Barnes, Edwin and Deng, Dong-Ling and Throckmorton, Robert E. and Wu, Yang-Le and S. Das Sarma} } @article { ISI:000369216400001, title = {Nonequilibrium many-body steady states via Keldysh formalism}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {1}, year = {2016}, month = {JAN 27}, pages = {014307}, chapter = {014307}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.014307}, author = {Maghrebi, Mohammad F. and Gorshkov, Alexey V.} } @article {14296, title = {Nonlinear looped band structure of Bose-Einstein condensates in an optical lattice}, journal = {Phys. Rev. A}, volume = {94}, year = {2016}, pages = {063634}, author = {Koller, Silvio B and Goldschmidt, Elizabeth A and Brown, Roger C and Wyllie, Robert and Wilson, Ryan W and Porto, J V} } @article {4655, title = {Non-Markovian Quantum Friction of Bright Solitons in Superfluids}, journal = {Phys. Rev. Lett.}, volume = {116}, year = {2016}, month = {05/2016}, pages = {225301}, doi = {10.1103/PhysRevLett.116.225301}, url = {http://link.aps.org/doi/10.1103/PhysRevLett.116.225301}, author = {Efimkin, Dmitry K. and Hofmann, Johannes and Galitski, Victor} } @article { ISI:000374964400012, title = {Pairing of j=3/2 Fermions in Half-Heusler Superconductors}, journal = {PHYSICAL REVIEW LETTERS}, volume = {116}, number = {17}, year = {2016}, month = {APR 27}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.116.177001}, author = {Brydon, P. M. R. and Wang, Limin and Weinert, M. and Agterberg, D. F.} } @article { ISI:000377796000001, title = {Parity effect in a mesoscopic Fermi gas}, journal = {PHYSICAL REVIEW A}, volume = {93}, number = {6}, year = {2016}, month = {JUN 13}, pages = {061602}, issn = {2469-9926}, doi = {10.1103/PhysRevA.93.061602}, author = {Hofmann, Johannes and Lobos, Alejandro M. and Galitski, Victor} } @article {ISI:000385398800001, title = {Physics of higher orbital bands in optical lattices: a review}, journal = {REPORTS ON PROGRESS IN PHYSICS}, volume = {79}, number = {11}, year = {2016}, month = {NOV}, pages = {116401}, abstract = {The orbital degree of freedom plays a fundamental role in understanding the unconventional properties in solid state materials. Experimental progress in quantum atomic gases has demonstrated that high orbitals in optical lattices can be used to construct quantum emulators of exotic models beyond natural crystals, where novel many-body states such as complex Bose-Einstein condensates and topological semimetals emerge. A brief introduction of orbital degrees of freedom in optical lattices is given and a summary of exotic orbital models and resulting many-body phases is provided. Experimental consequences of the novel phases are also discussed.}, issn = {0034-4885}, doi = {10.1088/0034-4885/79/11/116401}, author = {Li, Xiaopeng and Liu, W. Vincent} } @article {4436, title = {A Practical Phase Gate for Producing Bell Violations in Majorana Wires}, journal = {Phys. Rev. X}, volume = {6}, year = {2016}, month = {04/2016}, pages = {021005}, doi = {10.1103/PhysRevX.6.021005}, author = {Clarke, D J and Sau, J D and S. Das Sarma} } @article {ISI:000374560300010, title = {Projected Dipole Moments of Individual Two-Level Defects Extracted Using Circuit Quantum Electrodynamics}, journal = {PHYSICAL REVIEW LETTERS}, volume = {116}, number = {16}, year = {2016}, month = {APR 22}, pages = {167002}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.116.167002}, author = {Sarabi, B. and Ramanayaka, A. N. and Burin, A. L. and Wellstood, F. C. and Osborn, K. D.} } @article {ISI:000390349100003, title = {Proximity effect and Majorana bound states in clean semiconductor nanowires coupled to disordered superconductors}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {14}, year = {2016}, month = {OCT 27}, pages = {140505}, abstract = {We model a semiconductor wire with strong spin-orbit coupling which is proximity-coupled to a superconductor with chemical potential disorder. When tunneling at the semiconductor-superconductor interface is very weak, disorder in the superconductor does not affect the induced superconductivity nor, therefore, the effective topological superconductivity that emerges above a critical magnetic field. Here we demonstrate, nonperturbatively, how this result breaks down with stronger proximity coupling by obtaining the low-energy (i.e., subgap) excitation spectrum through direct numerical diagonalization of an appropriate Bogoliubov-de Gennes Hamiltonian. We find that the combination of strong proximity coupling and superconductor disorder suppresses the (nontopological) induced gap at zero magnetic field by disordering the induced pair potential. In the topological superconducting phase at large magnetic field, strong proximity coupling also reduces the localization length of Majorana bound states, such that the induced disorder eliminates the topological gap while bulk zero modes proliferate, even for short wires.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.140505}, author = {Cole, William S. and Sau, Jay D. and S. Das Sarma} } @article {6431, title = {Proximity effects in cold atom artificial graphene}, journal = {2D Materials}, volume = {4}, year = {2016}, month = {12/2016}, abstract = {Cold atoms in an optical lattice with brick-wall geometry have been used to mimic graphene, a two-dimensional material with characteristic Dirac excitations. Here we propose to bring such artificial graphene into the proximity of a second atomic layer with a square lattice geometry. For non-interacting fermions, we find that such bilayer system undergoes a phase transition from a graphene-like semi-metal phase, characterized by a band structure with Dirac points, to a gapped band insulator phase. In the presence of attractive interactions between fermions with pseudospin-1/2 degree of freedom, a competition between semi-metal and superfluid behavior is found at the mean-field level. Using the quantum Monte Carlo method, we also investigate the case of strong repulsive interactions. In the Mott phase, each layer exhibits a different amount of long-range magnetic order. Upon coupling both layers, a valence-bond crystal is formed at a critical coupling strength. Finally, we discuss how these bilayer systems could be realized in existing cold atom experiments.

}, doi = {10.1088/2053-1583/aa50c6}, url = {http://iopscience.iop.org/article/10.1088/2053-1583/aa50c6/meta;jsessionid=D34C5DE028C6A9A2A9B6D6A0A65569AF.c2.iopscience.cld.iop.org}, author = {Tobias Grass and Ravindra W Chhajlany and Leticia Tarruell and Vittorio Pellegrini and Maciej Lewenstein} } @article {ISI:000374726000029, title = {QUANTUM CONNECTIONS}, journal = {SCIENTIFIC AMERICAN}, volume = {314}, number = {5}, year = {2016}, month = {MAY}, pages = {50-57}, issn = {0036-8733}, author = {Monroe, Christopher R. and Schoelkopf, Robert J. and Lukin, Mikhail D.} } @article {ISI:000376992800002, title = {Quantum model for entropic springs}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {21}, year = {2016}, month = {JUN 2}, pages = {214102}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.214102}, author = {Wang, Chiao-Hsuan and Taylor, Jacob M.} } @article { ISI:000376908700003, title = {Quantum nonergodicity and fermion localization in a system with a single-particle mobility edge}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {18}, year = {2016}, month = {MAY 31}, pages = {184204}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.184204}, author = {Li, Xiaopeng and Pixley, J. H. and Deng, Dong-Ling and Ganeshan, Sriram and S. Das Sarma} } @article { ISI:000370215200053, title = {Quantum Phase Slips in 6 mm Long Niobium Nanowire}, journal = {NANO LETTERS}, volume = {16}, number = {2}, year = {2016}, month = {FEB}, pages = {1173-1178}, issn = {1530-6984}, doi = {10.1021/acs.nanolett.5b04473}, author = {Zhao, Weiwei and Liu, Xin and Chan, M. H. W.} } @article {4154, title = {A quantum phase switch between a single solid-state spin and a photon}, journal = {Nature Nanotechnology}, volume = {11}, year = {2016}, month = {02/2016}, pages = {539}, doi = {10.1038/nnano.2015.334}, url = {http://www.nature.com/nnano/journal/vaop/ncurrent/full/nnano.2015.334.html}, author = {Sun, Shuo and Kim, Hyochul and Solomon, Glenn S. and Waks, Edo} } @article { ISI:000383144000007, title = {Quantum phases of interacting electrons in three-dimensional dirty Dirac semimetals}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {11}, year = {2016}, month = {SEP 14}, pages = {115137}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.115137}, author = {Roy, Bitan and S. Das Sarma} } @article {ISI:000383849400001, title = {Quantum-Enhanced Machine Learning}, journal = {PHYSICAL REVIEW LETTERS}, volume = {117}, number = {13}, year = {2016}, month = {SEP 20}, pages = {130501}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.117.130501}, author = {Dunjko, Vedran and Taylor, Jacob M. and Briegel, Hans J.} } @article {4416, title = {Radio Frequency Tunable Oscillator Device Based on a SmB6 Microcrystal}, journal = {Phys. Rev. Lett.}, volume = {116}, year = {2016}, month = {04/2016}, pages = {166603}, doi = {10.1103/PhysRevLett.116.166603}, author = {Stern, Alex and Efimkin, Dmitry K. and Galitski, Victor and Fisk, Zachary and Xia, Jing} } @article { ISI:000367835400023, title = {Raman coherence in a circuit quantum electrodynamics lambda system}, journal = {NATURE PHYSICS}, volume = {12}, number = {1}, year = {2016}, month = {JAN}, pages = {75-U104}, issn = {1745-2473}, doi = {10.1038/NPHYS3537}, author = {Novikov, S. and Sweeney, T. and Robinson, J. E. and Premaratne, S. P. and Suri, B. and Wellstood, F. C. and Palmer, B. S.} } @article { ISI:000378876200001, title = {Rare-Region-Induced Avoided Quantum Criticality in Disordered Three-Dimensional Dirac and Weyl Semimetals}, journal = {PHYSICAL REVIEW X}, volume = {6}, number = {2}, year = {2016}, month = {JUN 29}, pages = {021042}, issn = {2160-3308}, doi = {10.1103/PhysRevX.6.021042}, author = {Pixley, J. H. and Huse, David A. and S. Das Sarma} } @article {ISI:000373727800001, title = {Rashba realization: Raman with RF}, journal = {NEW JOURNAL OF PHYSICS}, volume = {18}, year = {2016}, month = {APR 1}, pages = {033035}, issn = {1367-2630}, doi = {10.1088/1367-2630/18/3/033035}, author = {Campbell, D. L. and Ian B Spielman} } @article {ISI:000375524900002, title = {Realizing exactly solvable SU(N) magnets with thermal atoms}, journal = {PHYSICAL REVIEW A}, volume = {93}, number = {5}, year = {2016}, month = {MAY 6}, pages = {051601}, issn = {2469-9926}, doi = {10.1103/PhysRevA.93.051601}, author = {Beverland, Michael E. and Alagic, Gorjan and Martin, Michael J. and Koller, Andrew P. and Rey, Ana M. and Gorshkov, Alexey V.} } @article {ISI:000390246200008, title = {Real-space mean-field theory of a spin-1 Bose gas in synthetic dimensions}, journal = {PHYSICAL REVIEW A}, volume = {94}, number = {6}, year = {2016}, month = {DEC 15}, pages = {063613}, abstract = {The internal degrees of freedom provided by ultracold atoms provide a route for realizing higher dimensional physics in systems with limited spatial dimensions. Nonspatial degrees of freedom in these systems are dubbed {\textquoteleft}{\textquoteleft}synthetic dimensions.{{\textquoteright}{\textquoteright}} This connection is useful from an experimental standpoint but complicated by the fact that interactions alter the condensate ground state. Here we use the Gross-Pitaevskii equation to study the ground-state properties of a spin-1 Bose gas under the combined influence of an optical lattice, spatially varying spin-orbit coupling, and interactions at the mean-field level. The associated phases depend on the sign of the spin-dependent interaction parameter and the strength of the spin-orbit field. We find {\textquoteleft}{\textquoteleft}charge{{\textquoteright}{\textquoteright}}- and spin-density-wave phases which are directly related to helical spin order in real space and affect the behavior of edge currents in the synthetic dimension. We determine the resulting phase diagram as a function of the spin-orbit coupling and spin-dependent interaction strength, considering both attractive (ferromagnetic) and repulsive (polar) spin-dependent interactions, and we provide a direct comparison of our results with the noninteracting case. Our findings are applicable to current and future experiments, specifically with Rb-87, Li-7, K-41, and Na-23.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.94.063613}, author = {Hurst, Hilary M. and Wilson, Justin H. and Pixley, J. H. and Ian B Spielman and Natu, Stefan S.} } @article {ISI:000375705300002, title = {Renyi information from entropic effects in one higher dimension}, journal = {JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT}, year = {2016}, month = {APR}, pages = {043102}, abstract = {Computing entanglement entropy and its cousins is often challenging even in the simplest continuum and lattice models, partly because such entropies depend nontrivially on all geometric characteristics of the entangling region. Quantum information measures between two or more regions are even more complicated, but contain more, and universal, information. In this paper, we focus on Renyi entropy and information of the order n = 2. For a free field theory, we show that these quantities are mapped to the change of the thermodynamic free energy by introducing boundaries subject to Dirichlet and Neumann boundary conditions in one higher dimension. This mapping allows us to exploit the powerful tools available in the context of thermal Casimir effect, specifically a multipole expansion suited for computing the Renyi information between arbitrarily-shaped regions. In particular, we compute the Renyi information between two disk-shaped regions at an arbitrary separation distance. We provide an alternative representation of the Renyi information as a sum over closed-loop polymers, which establishes a connection to purely entropic effects, and proves useful in deriving information inequalities. Finally, we discuss extensions of our results beyond free field theories.}, issn = {1742-5468}, doi = {10.1088/1742-5468/2016/04/043102}, author = {Maghrebi, Mohammad F.} } @article {ISI:000384068400002, title = {Role of boundary conditions, topology, and disorder in the chiral magnetic effect in Weyl semimetals}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {11}, year = {2016}, month = {SEP 27}, pages = {115160}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.115160}, author = {Alavirad, Yahya and Sau, Jay D.} } @article {ISI:000388814500011, title = {Self-organization of atoms coupled to a chiral reservoir}, journal = {PHYSICAL REVIEW A}, volume = {94}, number = {5}, year = {2016}, month = {NOV 29}, pages = {053855}, abstract = {Tightly confined modes of light, as in optical nanofibers or photonic crystal waveguides, can lead to large optical coupling in atomic systems, which mediates long-range interactions between atoms. These one-dimensional systems can naturally possess couplings that are asymmetric between modes propagating in different directions. Strong long-range interaction among atoms via these modes can drive them to a self-organized periodic distribution. In this paper, we examine the self-organizing behavior of atoms in one dimension coupled to a chiral reservoir. We determine the solution to the equations of motion in different parameter regimes, relative to both the detuning of the pump laser that initializes the atomic dipole-dipole interactions and the degree of reservoir chirality. In addition, we calculate possible experimental signatures such as reflectivity from self-organized atoms and motional sidebands.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.94.053855}, author = {Eldredge, Zachary and Solano, Pablo and Chang, Darrick and Gorshkov, Alexey V.} } @article {ISI:000390255800014, title = {Semisynthetic zigzag optical lattice for ultracold bosons}, journal = {PHYSICAL REVIEW A}, volume = {94}, number = {6}, year = {2016}, month = {DEC 22}, pages = {063632}, abstract = {We propose a cold-atom realization of a zigzag ladder. The two legs of the ladder correspond to a {\textquoteleft}{\textquoteleft}synthetic{{\textquoteright}{\textquoteright}} dimension given by two internal (spin) states of the atoms, so that tunneling between them can be realized as a laser-assisted process. The zigzag geometry is achieved by employing a spin-dependent optical lattice with the site position depending on the internal atomic state, i.e., on the ladder{\textquoteright}s leg. The lattice offers a possibility to tune the single-particle dispersion from a double-well to a single-minimum configuration. In contrast to previously considered semisynthetic lattices with a square geometry, the tunneling in the synthetic dimension is accompanied by spatial displacements of atoms. Therefore, the atom-atom interactions are nonlocal and act along the diagonal (semisynthetic) direction. We investigate the ground-state properties of the system for the case of strongly interacting bosons. In particular, we find that the interplay between the frustration induced by the magnetic field and the interactions gives rise to an interesting gapped phase at fractional filling factors corresponding to one particle per magnetic unit cell.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.94.063632}, author = {Anisimovas, E. and Raciunas, M. and Straeter, C. and Eckardt, A. and Ian B Spielman and Juzeliunas, G.} } @article {ISI:000383977500002, title = {Serialized quantum error correction protocol for high-bandwidth quantum repeaters}, journal = {NEW JOURNAL OF PHYSICS}, volume = {18}, year = {2016}, month = {SEP 2}, pages = {093008}, issn = {1367-2630}, doi = {10.1088/1367-2630/18/9/093008}, author = {Glaudell, A. N. and Waks, E. and Taylor, J. M.} } @article {ISI:000379697300009, title = {Single-shot optical readout of a quantum bit using cavity quantum electrodynamics}, journal = {PHYSICAL REVIEW A}, volume = {94}, number = {1}, year = {2016}, month = {JUL 5}, pages = {012307}, issn = {2469-9926}, doi = {10.1103/PhysRevA.94.012307}, author = {Sun, Shuo and Waks, Edo} } @article {ISI:000381468300006, title = {Sisyphus Thermalization of Photons in a Cavity-Coupled Double Quantum Dot}, journal = {PHYSICAL REVIEW LETTERS}, volume = {117}, number = {5}, year = {2016}, month = {JUL 25}, pages = {056801}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.117.056801}, author = {Gullans, M. J. and Stehlik, J. and Liu, Y. -Y. and Eichler, C. and Petta, J. R. and Taylor, J. M.} } @article { ISI:000368286300013, title = {SU(3) Quantum Hall Ferromagnetism in SnTe}, journal = {PHYSICAL REVIEW LETTERS}, volume = {116}, number = {2}, year = {2016}, month = {JAN 15}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.116.026803}, author = {Li, Xiao and Zhang, Fan and MacDonald, A. H.} } @article {ISI:000390960500015, title = {Subwavelength-width optical tunnel junctions for ultracold atoms}, journal = {PHYSICAL REVIEW A}, volume = {94}, number = {6}, year = {2016}, month = {DEC 27}, pages = {063422}, abstract = {We propose a method for creating far-field optical barrier potentials for ultracold atoms with widths that are narrower than the diffraction limit and can approach tens of nanometers. The reduced widths stem from the nonlinear atomic response to control fields that create spatially varying dark resonances. The subwavelength barrier is the result of the geometric scalar potential experienced by an atom prepared in such a spatially varying dark state. The performance of this technique, as well as its applications to the study of many-body physics and to the implementation of quantum-information protocols with ultracold atoms, are discussed, with a focus on the implementation of tunnel junctions.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.94.063422}, author = {Jendrzejewski, F. and Eckel, S. and Tiecke, T. G. and Juzeliunas, G. and Campbell, G. K. and Jiang, Liang and Gorshkov, A. V.} } @article {ISI:000381882800009, title = {Superfluid transport dynamics in a capacitive atomtronic circuit}, journal = {PHYSICAL REVIEW A}, volume = {94}, number = {2}, year = {2016}, month = {AUG 22}, pages = {023626}, abstract = {We simulate transport in an atomtronic circuit of a Bose-Einstein condensate that flows from a source region into a drain through a gate channel. The time-dependent Gross-Pitaevskii equation (GPE) solution matches the data of a recent experiment. The atomtronic circuit is found to be similar to a variable-resistance RLC circuit, which is critically damped at early times and shows LC oscillations later. The GPE also predicts atom loss from the drain. Studies of the dependence of condensate transport upon gate parameters suggest the utility of the GPE for investigation of atomtronic circuits.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.94.023626}, author = {Li, Aijun and Eckel, Stephen and Eller, Benjamin and Warren, Kayla E. and Clark, Charles W. and Edwards, Mark} } @article { ISI:000377499700002, title = {Surface plasmon polaritons in topological Weyl semimetals}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {24}, year = {2016}, month = {JUN 9}, pages = {241402}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.241402}, author = {Hofmann, Johannes and S. Das Sarma} } @article {ISI:000384214600001, title = {Synthetic gauge potentials for ultracold neutral atoms}, journal = {JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS}, volume = {48}, number = {18}, year = {2016}, month = {SEP 28}, pages = {183001}, issn = {0953-4075}, doi = {10.1088/0953-4075/49/18/183001}, author = {Lin, Yu-Ju and Ian B Spielman} } @article { ISI:000376242200008, title = {Three-photon process for producing a degenerate gas of metastable alkaline-earth-metal atoms}, journal = {PHYSICAL REVIEW A}, volume = {93}, number = {5}, year = {2016}, month = {MAY 18}, pages = {053417}, issn = {2469-9926}, doi = {10.1103/PhysRevA.93.053417}, author = {Barker, D. S. and Pisenti, N. C. and Reschovsky, B. J. and Campbell, G. K.} } @article { ISI:000367187000009, title = {Topological defect lasers}, journal = {JOURNAL OF OPTICS}, volume = {18}, number = {1}, year = {2016}, month = {JAN}, issn = {2040-8978}, doi = {10.1088/2040-8978/18/1/014005}, author = {Knitter, Sebastian and Liew, Seng Fatt and Xiong, Wen and Guy, Mikhael I. and Solomon, Glenn S. and Cao, Hui} } @article { ISI:000372709600010, title = {Topological phases via engineered orbital hybridization in noncentrosymmetric optical lattices}, journal = {PHYSICAL REVIEW A}, volume = {93}, number = {3}, year = {2016}, month = {MAR 23}, issn = {2469-9926}, doi = {10.1103/PhysRevA.93.033643}, author = {Liu, Bo and Li, Xiaopeng and Liu, W. Vincent} } @article { ISI:000367780600001, title = {Topological phases with long-range interactions}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {4}, year = {2016}, month = {JAN 8}, pages = {041102}, issn = {1098-0121}, doi = {10.1103/PhysRevB.93.041102}, author = {Gong, Z. -X. and Maghrebi, M. F. and Hu, A. and Wall, M. L. and Foss-Feig, M. and Gorshkov, A. V.} } @article {ISI:000381770500058, title = {Topologically robust transport of entangled photons in a 2D photonic system}, journal = {OPTICS EXPRESS}, volume = {24}, number = {14}, year = {2016}, month = {JUL 11}, pages = {15631-15641}, issn = {1094-4087}, doi = {10.1364/OE.24.015631}, author = {Mittal, Sunil and Orre, Venkata Vikram and Hafezi, Mohammad} } @article {ISI:000379747100019, title = {Toward optical quantum information processing with quantum dots coupled to microstructures {[}Invited]}, journal = {JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS}, volume = {33}, number = {7}, year = {2016}, month = {JUL 1}, pages = {C160}, issn = {0740-3224}, doi = {10.1364/JOSAB.33.00C160}, author = {Gazzano, Olivier and Solomon, Glenn S.} } @article { ISI:000377301200003, title = {Transport of Dirac electrons in a random magnetic field in topological heterostructures}, journal = {PHYSICAL REVIEW B}, volume = {93}, number = {24}, year = {2016}, month = {JUN 6}, issn = {2469-9950}, doi = {10.1103/PhysRevB.93.245111}, author = {Hurst, Hilary M. and Efimkin, Dmitry K. and Galitski, Victor} } @article {ISI:000389023600008, title = {Two coupled nonlinear cavities in a driven-dissipative environment}, journal = {PHYSICAL REVIEW A}, volume = {94}, number = {6}, year = {2016}, month = {DEC 1}, pages = {063805}, abstract = {We investigate two coupled nonlinear cavities that are coherently driven in a dissipative environment. We perform semiclassical, numerical, and analytical quantum studies of this dimer model when both cavities are symmetrically driven. In the semiclassical analysis, we find steady-state solutions with different photon occupations in two cavities. Such states can be considered analogs of the closed system double-well symmetry-breaking states. We analyze the occurrence and properties of these localized states in the system parameter space and examine how the symmetry-breaking states, in the form of a bistable pair, are associated with the single-cavity bistable behavior. In a full quantum calculation of the master equation dynamics that includes quantum fluctuations, the symmetry-breaking states and bistability disappear due to the quantum fluctuations. In the quantum trajectory picture, we observe enhanced quantum jumps and switching, which indicate the presence of the underlying semiclassical symmetry-breaking states. Finally, we present a set of analytical solutions for the steady-state correlation functions by using the complex P representation and discuss its regime of validity.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.94.063805}, author = {Cao, Bin and Mahmud, Khan W. and Hafezi, Mohammad} } @article {ISI:000388016200001, title = {Two-dimensionally confined topological edge states in photonic crystals}, journal = {NEW JOURNAL OF PHYSICS}, volume = {18}, year = {2016}, month = {NOV 7}, pages = {113013}, abstract = {We present an all-dielectric photonic crystal structure that supports two-dimensionally confined helical topological edge states. The topological properties of the system are controlled by the crystal parameters. An interface between two regions of differing band topologies gives rise to topological edge states confined in a dielectric slab that propagate around sharp corners without backscattering. Three-dimensional finite-difference time-domain calculations show these edges to be confined in the out-of-plane direction by total internal reflection. Such nanoscale photonic crystal architectures could enable strong interactions between photonic edge states and quantum emitters.}, issn = {1367-2630}, doi = {10.1088/1367-2630/18/11/113013}, author = {Barik, Sabyasachi and Miyake, Hirokazu and DeGottardi, Wade and Waks, Edo and Hafezi, Mohammad} } @article {ISI:000378847400004, title = {Two-photon interference from a bright single-photon source at telecom wavelengths}, journal = {OPTICA}, volume = {3}, number = {6}, year = {2016}, month = {JUN 20}, pages = {577-584}, issn = {2334-2536}, doi = {10.1364/OPTICA.3.000577}, author = {Kim, Je-Hyung and Cai, Tao and Richardson, Christopher J. K. and Leavitt, Richard P. and Waks, Edo} } @article {ISI:000387625000051, title = {Two-Photon Interference from the Far-Field Emission of Chip-Integrated Cavity-Coupled Emitters}, journal = {NANO LETTERS}, volume = {16}, number = {11}, year = {2016}, month = {NOV}, pages = {7061-7066}, abstract = {Interactions between solid-state quantum emitters and cavities are important for a broad range of applications in quantum communication, linear optical quantum computing, nonlinear photonics, and photonic quantum simulation. These applications often require combining many devices on a single chip with identical emission wavelengths in order to generate two-photon interference, the primary mechanism for achieving effective photon photon interactions. Such integration remains extremely challenging due to inhomogeneous broadening and fabrication errors that randomize the resonant frequencies of both the emitters and cavities. In this Letter, we demonstrate two-photon interference from independent cavity-coupled emitters on the same chip, providing a potential solution to this long-standing problem. We overcome spectral mismatch between different cavities due to fabrication errors by depositing and locally evaporating a thin layer of condensed nitrogen. We integrate optical heaters to tune individual dots within each cavity to the same resonance with better than 3 mu eV of precision. Combining these tuning methods, we demonstrate two-photon interference between two devices spaced by less than 15 mu m on the same chip with a postselected visibility of 33\%, which is limited by timing resolution of the detectors and background. These results pave the way to integrate multiple quantum light sources on the same chip to develop quantum photonic devices.}, issn = {1530-6984}, doi = {10.1021/acs.nanolett.6b03295}, author = {Kim, Je-Hyung and Richardson, Christopher J. K. and Leavitt, Richard P. and Waks, Edo} } @article {ISI:000392096800044, title = {An ultra-low noise, high-voltage piezo-driver}, journal = {REVIEW OF SCIENTIFIC INSTRUMENTS}, volume = {87}, number = {12}, year = {2016}, month = {DEC}, pages = {124702}, abstract = {We present an ultra-low noise, high-voltage driver suited for use with piezoelectric actuators and other low-current applications. The architecture uses a flyback switching regulator to generate up to 250 V in our current design, with an output of 1 kV or more possible with small modifications. A high slew-rate op-amp suppresses the residual switching noise, yielding a total root-mean-square noise of approximate to 100 mu V (1 Hz-100 kHz). A low-voltage (+/- 10 V), high bandwidth signal can be summed with unity gain directly onto the output, making the driver well-suited for closed-loop feedback applications. Digital control enables both repeatable setpoints and sophisticated control logic, and the circuit consumes less than 150 mA at +/- 15 V.}, issn = {0034-6748}, doi = {10.1063/1.4969059}, author = {Pisenti, N. C. and Restelli, A. and Reschovsky, B. J. and Barker, D. S. and Campbell, G. K.} } @article { ISI:000383238600001, title = {Uncovering the hidden quantum critical point in disordered massless Dirac and Weyl semimetals}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {12}, year = {2016}, month = {SEP 8}, pages = {121107}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.121107}, author = {Pixley, J. H. and Huse, David A. and S. Das Sarma} } @article {ISI:000371389100004, title = {Understanding analog quantum simulation dynamics in coupled ion-trap qubits}, journal = {PHYSICAL REVIEW A}, volume = {93}, number = {2}, year = {2016}, month = {FEB 29}, pages = {022332}, issn = {2469-9926}, doi = {10.1103/PhysRevA.93.022332}, author = {Wu, Yang-Le and S. Das Sarma} } @article {ISI:000391982700001, title = {Universal optical conductivity of a disordered Weyl semimetal}, journal = {SCIENTIFIC REPORTS}, volume = {6}, year = {2016}, month = {AUG 30}, pages = {32446}, abstract = {Topological Weyl semimetals, besides manifesting chiral anomaly, can also accommodate a disorder-driven unconventional quantum phase transition into a metallic phase. A fundamentally and practically important question in this regard concerns an experimentally measurable quantity that can clearly distinguish these two phases. We show that the optical conductivity while serving this purpose can also play the role of a bonafide order parameter across such disorder-driven semimetal-metal quantum phase transition by virtue of displaying distinct scaling behavior in the semimetallic and metallic phases, as well as inside the quantum critical fan supporting a non-Fermi liquid. We demonstrate that the correction to the dielectric constant and optical conductivity in a dirty Weyl semimetal due to weak disorder is independent of the actual nature of point-like impurity scatterers. Therefore, optical conductivity can be used as an experimentally measurable quantity to study the critical properties and to pin the universality class of the disorder-driven quantum phase transition in Weyl semimetals.}, issn = {2045-2322}, doi = {10.1038/srep32446}, author = {Roy, Bitan and Juricic, Vladimir and S. Das Sarma} } @article {ISI:000387905800007, title = {Vortex nucleation in a Bose-Einstein condensate: from the inside out}, journal = {NEW JOURNAL OF PHYSICS}, volume = {18}, year = {2016}, month = {NOV 4}, pages = {113009}, abstract = {We observed a new mechanism for vortex nucleation in Bose-Einstein condensates (BECs) subject to synthetic magnetic fields. We made use of a strong synthetic magnetic field initially localized between a pair of merging BECs to rapidly create vortices in the bulk of the merged condensate. Unlike previous implementations and in agreement with our Gross-Pitaevskii equation simulations, our dynamical process rapidly injects vortices into our system{\textquoteright}s bulk, and with initial number in excess of the system{\textquoteright}s equilibrium vortex number.}, issn = {1367-2630}, doi = {10.1088/1367-2630/18/11/113009}, author = {Price, R. M. and Trypogeorgos, D. and Campbell, D. L. and Putra, A. and Valdes-Curiel, A. and Ian B Spielman} } @article {ISI:000388818000002, title = {Weyl fermions with arbitrary monopoles in magnetic fields: Landau levels, longitudinal magnetotransport, and density-wave ordering}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {19}, year = {2016}, month = {NOV 28}, pages = {195144}, abstract = {We theoretically address the effects of strong magnetic fields in three-dimensional Weyl semimetals (WSMs) built out of Weyl nodes with a monopole charge n. For n = 1, 2, and 3 we realize single, double, and triple WSM, respectively, and the monopole charge n determines the integer topological invariant of the WSM. Within the linearized continuum description, the quasiparticle spectrum is then composed of Landau levels (LLs), containing exactly n number of chiral zeroth Landau levels (ZLLs), irrespective of the orientation of the magnetic field. In the presence of strong backscattering, for example (due to quenched disorder associated with random impurities), these systems generically give rise to longitudinal magnetotransport. Restricting ourselves to the quantum limit (and assuming only the subspace of the ZLLs to be partially filled) and mainly accounting for Gaussian impurities, we show that the longitudinal magnetoconductivity (LMC) in all members of the Weyl family displays a positive linear-B scaling when the field is applied along the axis that separates the Weyl nodes. But, in double and triple WSM, LMC displays a smooth crossover to a nonlinear B dependence as the field is tilted away from such a high-symmetry direction. In addition, due to the enhanced density of states, the LL quantization can trigger instabilities toward the formation of translational symmetry-breaking density-wave orderings for sufficiently weak interaction (BCS instability), which gaps out the ZLLs. Concomitantly as the temperature (magnetic field) is gradually decreased (increased) the LMC becomes negative. Thus WSMs with arbitrary monopole charge (n) can host an intriguing interplay of LL quan