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 { 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 {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: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: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: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: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: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: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: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: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: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: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: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: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: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: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: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: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: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: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: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: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: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: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: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: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: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 { 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: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: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 {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:000361376200011, title = {Bound States of a Ferromagnetic Wire in a Superconductor}, journal = {PHYSICAL REVIEW LETTERS}, volume = {115}, number = {12}, year = {2015}, month = {SEP 18}, pages = {127003}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.115.127003}, author = {Sau, Jay D. and Brydon, P. M. R.} } @article { ISI:000364471100002, title = {Bulk disorder in the superconductor affects proximity-induced topological superconductivity}, journal = {PHYSICAL REVIEW B}, volume = {92}, number = {17}, year = {2015}, month = {NOV 12}, pages = {174512}, issn = {1098-0121}, doi = {10.1103/PhysRevB.92.174512}, author = {Hui, Hoi-Yin and Sau, Jay D. and S. Das Sarma} } @article { ISI:000356473300003, title = {Conductance spectroscopy of topological superconductor wire junctions}, journal = {PHYSICAL REVIEW B}, volume = {91}, number = {21}, year = {2015}, month = {JUN 18}, pages = {214513}, issn = {1098-0121}, doi = {10.1103/PhysRevB.91.214513}, author = {Setiawan, F. and Brydon, P. M. R. and Sau, Jay D. and S. Das Sarma} } @article { ISI:000364024800001, title = {Dynamical Detection of Topological Phase Transitions in Short-Lived Atomic Systems}, journal = {PHYSICAL REVIEW LETTERS}, volume = {115}, number = {19}, year = {2015}, month = {NOV 4}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.115.190401}, author = {Setiawan, F. and Sengupta, K. and Ian B Spielman and Sau, Jay D.} } @article { ISI:000358373600004, title = {Equivalence of topological mirror superconductivity and chiral superconductivity in one dimension}, journal = {PHYSICAL REVIEW B}, volume = {92}, number = {4}, year = {2015}, month = {JUL 22}, issn = {1098-0121}, doi = {10.1103/PhysRevB.92.045421}, author = {Dumitrescu, Eugene and Sharma, Girish and Sau, Jay D. and Tewari, Sumanta} } @article { ISI:000367065800003, title = {Excitonic and nematic instabilities on the surface of topological Kondo insulators}, journal = {PHYSICAL REVIEW B}, volume = {92}, number = {24}, year = {2015}, month = {DEC 21}, issn = {1098-0121}, doi = {10.1103/PhysRevB.92.245431}, author = {Roy, Bitan and Hofmann, Johannes and Stanev, Valentin and Sau, Jay D. and Galitski, Victor} } @article { ISI:000361665700003, title = {Magnetic catalysis and axionic charge density wave in Weyl semimetals}, journal = {PHYSICAL REVIEW B}, volume = {92}, number = {12}, year = {2015}, month = {SEP 22}, issn = {1098-0121}, doi = {10.1103/PhysRevB.92.125141}, author = {Roy, Bitan and Sau, Jay D.} } @article {ISI:000351341100004, title = {Majorana fermions in chiral topological ferromagnetic nanowires}, journal = {PHYSICAL REVIEW B}, volume = {91}, number = {9}, year = {2015}, month = {MAR 12}, pages = {094505}, issn = {1098-0121}, doi = {10.1103/PhysRevB.91.094505}, author = {Dumitrescu, Eugene and Roberts, Brenden and Tewari, Sumanta and Sau, Jay D. and S. Das Sarma} } @article {ISI:000350480100001, title = {Majorana fermions in ferromagnetic chains on the surface of bulk spin-orbit coupled s-wave superconductors}, journal = {SCIENTIFIC REPORTS}, volume = {5}, year = {2015}, month = {MAR 6}, pages = {8880}, issn = {2045-2322}, doi = {10.1038/srep08880}, author = {Hui, Hoi-Yin and Brydon, P. M. R. and Sau, Jay D. and Tewari, S. and S. Das Sarma} } @article { ISI:000358372100002, title = {Proposal to probe quantum nonlocality of Majorana fermions in tunneling experiments}, journal = {PHYSICAL REVIEW B}, volume = {92}, number = {2}, year = {2015}, month = {JUL 22}, issn = {1098-0121}, doi = {10.1103/PhysRevB.92.020511}, author = {Sau, Jay D. and Swingle, Brian and Tewari, Sumanta} } @article { ISI:000357263100001, title = {Substrate-induced Majorana renormalization in topological nanowires}, journal = {NEW JOURNAL OF PHYSICS}, volume = {17}, year = {2015}, month = {JUL 2}, pages = {075001}, issn = {1367-2630}, doi = {10.1088/1367-2630/17/7/075001}, author = {S. Das Sarma and Hui, Hoi-Yin and Brydon, P. M. R. and Sau, Jay D.} } @article {ISI:000352302300005, title = {Topological Yu-Shiba-Rusinov chain from spin-orbit coupling}, journal = {PHYSICAL REVIEW B}, volume = {91}, number = {6}, year = {2015}, month = {FEB 17}, pages = {064505}, issn = {1098-0121}, doi = {10.1103/PhysRevB.91.064505}, author = {Brydon, P. M. R. and S. Das Sarma and Hui, Hoi-Yin and Sau, Jay D.} } @article { ISI:000358599300004, title = {Universal spin-triplet superconducting correlations of Majorana fermions}, journal = {PHYSICAL REVIEW B}, volume = {92}, number = {1}, year = {2015}, month = {JUL 27}, pages = {014513}, issn = {1098-0121}, doi = {10.1103/PhysRevB.92.014513}, author = {Liu, Xin and Sau, Jay D. and S. Das Sarma} } @article { ISI:000341263400005, title = {Competing charge-density wave, magnetic, and topological ground states at and near Dirac points in graphene in axial magnetic fields}, journal = {PHYSICAL REVIEW B}, volume = {90}, number = {7}, year = {2014}, month = {AUG 25}, issn = {1098-0121}, doi = {10.1103/PhysRevB.90.075427}, author = {Roy, Bitan and Sau, Jay D.} } @article {ISI:000353707900002, title = {Disorder-induced subgap states and Majorana zero-energy edge modes in two-dimensional topological insulator-superconductor hybrid structures}, journal = {PHYSICAL REVIEW B}, volume = {90}, number = {17}, year = {2014}, month = {NOV 25}, pages = {174206}, issn = {1098-0121}, doi = {10.1103/PhysRevB.90.174206}, author = {Hui, Hoi-Yin and Sau, Jay D. and S. Das Sarma} } @article { ISI:000341258500007, title = {Generalized Eilenberger theory for Majorana zero-mode-carrying disordered p-wave superconductors}, journal = {PHYSICAL REVIEW B}, volume = {90}, number = {6}, year = {2014}, month = {AUG 27}, issn = {1098-0121}, doi = {10.1103/PhysRevB.90.064516}, author = {Hui, Hoi-Yin and Sau, Jay D. and S. Das Sarma} } @article { ISI:000349891600004, title = {Magnetic field response and chiral symmetry of time-reversal-invariant topological superconductors}, journal = {PHYSICAL REVIEW B}, volume = {90}, number = {24}, year = {2014}, month = {DEC 31}, issn = {1098-0121}, doi = {10.1103/PhysRevB.90.245438}, author = {Dumitrescu, Eugene and Sau, Jay D. and Tewari, Sumanta} } @article { ISI:000334594900003, title = {Migdal{\textquoteright}s theorem and electron-phonon vertex corrections in Dirac materials}, journal = {PHYSICAL REVIEW B}, volume = {89}, number = {16}, year = {2014}, month = {APR 17}, issn = {1098-0121}, doi = {10.1103/PhysRevB.89.165119}, author = {Roy, Bitan and Sau, Jay D. and S. Das Sarma} } @article { ISI:000345422200008, title = {Odd-parity superconductivity from phonon-mediated pairing: Application to CuxBi2Se3}, journal = {PHYSICAL REVIEW B}, volume = {90}, number = {18}, year = {2014}, month = {NOV 14}, issn = {1098-0121}, doi = {10.1103/PhysRevB.90.184512}, author = {Brydon, P. M. R. and S. Das Sarma and Hui, Hoi-Yin and Sau, Jay D.} } @article { ISI:000349342300006, title = {Proximity-induced superconductivity and Josephson critical current in quantum spin Hall systems}, journal = {PHYSICAL REVIEW B}, volume = {90}, number = {22}, year = {2014}, month = {DEC 18}, pages = {224517}, issn = {1098-0121}, doi = {10.1103/PhysRevB.90.224517}, author = {Hui, Hoi-Yin and Lobos, Alejandro M. and Sau, Jay D. and S. Das Sarma} } @article { ISI:000344014700003, title = {Suppressing defect production during passage through a quantum critical point}, journal = {PHYSICAL REVIEW B}, volume = {90}, number = {10}, year = {2014}, month = {SEP 22}, issn = {1098-0121}, doi = {10.1103/PhysRevB.90.104306}, author = {Sau, Jay D. and Sengupta, K.} } @article { ISI:000344022600002, title = {Surface theory of a family of topological Kondo insulators}, journal = {PHYSICAL REVIEW B}, volume = {90}, number = {15}, year = {2014}, month = {OCT 21}, issn = {1098-0121}, doi = {10.1103/PhysRevB.90.155314}, author = {Roy, Bitan and Sau, Jay D. and Dzero, Maxim and Victor M Galitski} } @article { ISI:000348728400003, title = {Transport in Two-Dimensional Disordered Semimetals}, journal = {PHYSICAL REVIEW LETTERS}, volume = {113}, number = {18}, year = {2014}, month = {OCT 27}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.113.186801}, author = {Knap, Michael and Sau, Jay D. and Halperin, Bertrand I. and Demler, Eugene} } @article { ISI:000306995000036, title = {Realizing a robust practical Majorana chain in a quantum-dot-superconductor linear array}, journal = {NATURE COMMUNICATIONS}, volume = {3}, year = {2012}, month = {JUL}, issn = {2041-1723}, doi = {10.1038/ncomms1966}, author = {Sau, Jay D. and S. Das Sarma} } @article { ISI:000312693900001, title = {Splitting of the zero-bias conductance peak as smoking gun evidence for the existence of the Majorana mode in a superconductor-semiconductor nanowire}, journal = {PHYSICAL REVIEW B}, volume = {86}, number = {22}, year = {2012}, month = {DEC 21}, issn = {1098-0121}, doi = {10.1103/PhysRevB.86.220506}, author = {S. Das Sarma and Sau, Jay D. and Stanescu, Tudor D.} } @article {2538, title = {Topological minigap in quasi-one-dimensional spin-orbit-coupled semiconductor Majorana wires}, journal = {PHYSICAL REVIEW B}, volume = {86}, year = {2012}, month = {JUL 5}, pages = {024504}, issn = {1098-0121}, doi = {10.1103/PhysRevB.86.024504}, author = {Tewari, Sumanta and Stanescu, T. D. and Sau, Jay D. and S. Das Sarma} } @article { ISI:000289742100023, title = {Electrodynamic and Excitonic Intertube Interactions in Semiconducting Carbon Nanotube Aggregates}, journal = {ACS NANO}, volume = {5}, number = {4}, year = {2011}, month = {APR}, pages = {2611-2618}, issn = {1936-0851}, doi = {10.1021/nn200427r}, author = {Crochet, Jared J. and Sau, Jay D. and Duque, Juan G. and Doorn, Stephen K. and Cohen, Marvin L.} } @article { ISI:000293128900003, title = {Majorana fermion exchange in quasi-one-dimensional networks}, journal = {PHYSICAL REVIEW B}, volume = {84}, number = {3}, year = {2011}, month = {JUL 25}, issn = {1098-0121}, doi = {10.1103/PhysRevB.84.035120}, author = {Clarke, David J. and Sau, Jay D. and Tewari, Sumanta} } @article { ISI:000290162000003, title = {Prediction of a gapless topological Haldane liquid phase in a one-dimensional cold polar molecular lattice}, journal = {PHYSICAL REVIEW B}, volume = {83}, number = {17}, year = {2011}, month = {MAY 3}, issn = {1098-0121}, doi = {10.1103/PhysRevB.83.174409}, author = {Kestner, J. P. and Wang, Bin and Sau, Jay D. and S. Das Sarma} } @article { ISI:000281280100001, title = {Spin squeezing of high-spin, spatially extended quantum fields}, journal = {NEW JOURNAL OF PHYSICS}, volume = {12}, year = {2010}, month = {AUG 25}, issn = {1367-2630}, doi = {10.1088/1367-2630/12/8/085011}, author = {Sau, Jay D. and Leslie, Sabrina R. and Cohen, Marvin L. and Stamper-Kurn, Dan M.} }