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March 13, 2018 | PFC | Research News

Two-toned light pattern creates steep quantum walls for atoms

Exotic physics can happen when quantum particles come together and talk to each other. Understanding such processes is challenging for scientists, because the particle interactions can be hard to glimpse and even harder to control. Moreover, modern computer simulations struggle to make sense of all the intricate dynamics going on in a large group of particles. Luckily, atoms cooled to near zero temperatures can provide insight into this problem.Lasers can make cold atoms mimic the physics seen in other systems—an approach that is familiar terrain for atomic physicists. They regularly use intersecting laser beams to capture atoms in a landscape of rolling hills and valleys called an optical lattice. Atoms, when cooled, don’t have enough energy to walk up the hills, and they get stuck in the valleys. In this environment, the atoms behave similarly to the electrons in the crystal structure of many solids, so this approach provides a straightforward way to learn about interactions inside real materials.But the conventional way to make optical lattices has some limitations. The wavelength of the laser light determines the location of the hills and valleys, and so the distance between neighboring valleys—and with that the spacing between atoms—can only be shrunk to half of the light’s wavelength. Bringing atoms closer than this limit could activate much stronger interactions between them and reveal effects that otherwise remain in the dark.Now, a team of scientists from the Joint Quantum Institute (JQI), in collaboration with researchers from the Institute for Quantum Optics and Quantum Information in Innsbruck, Austria, has circumvented the wavelength limit by leveraging the atoms’ inherent quantum features, which should allow atomic lattice neighbors to get closer than ever before. The new technique manages to squeeze the gentle lattice hills into steep walls separated by only one-fiftieth of the laser’s wavelength—25 times narrower than possible with conventional methods. The work, which is based on two prior theoretical proposals, was recently published in Physical Review Letters.
March 9, 2018 | Podcast

Physics at the edge of the world

Deep within the ice covering the South Pole, thousands of sensitive cameras strain their digital eyes in search of a faint blue glow—light that betrays the presence of high-energy neutrinos. For this episode, Chris sat down with UMD graduate student Liz Friedman and physics professor Kara Hoffman to learn more about IceCube, the massive underground neutrino observatory located in one of the most desolate spots on Earth. It turns out that IceCube is blind to the highest-energy neutrinos, and Friedman is heading down to the South Pole to help install stations for a new observatory—the Askaryan Radio Array—which uses radio waves instead of blue light to tune into the whispers of these ghostly visitors.
February 15, 2018 | People News

JQI Fellow Barkeshli receives 2018 Sloan Research Fellowship

Maissam Barkeshli, an assistant professor of physics at the University of Maryland and fellow of the Joint Quantum Institute, has been awarded a 2018 Sloan Research Fellowship. Granted by the Alfred P. Sloan Foundation, this award identifies 126 early-career scientists based on their potential to contribute fundamentally significant research to a wider academic community. Barkeshli, a theoretical condensed matter physicist interested in complex quantum many-body phenomena, will use the fellowship to further his research into the collective behavior that emerges in systems of strongly interacting particles governed by the laws of quantum mechanics.“I am honored to receive this prestigious fellowship,” said Barkeshli. “It represents an affirmation of my work by distinguished members of the physics community, and it encourages me to continue my efforts in understanding the complexities of quantum matter.”Barkeshli’s research mixes physics with mathematics and draws motivation from the ongoing pursuit to build next-generation computing devices ruled by quantum physics. Beyond the applications, his research explores the many ways that atoms and electrons—prototypical quantum particles—can combine in large numbers to produce a range of novel behaviors. For example, interesting things seem to happen at the interface between two different quantum materials. In 2014, Barkeshli and several colleagues showed that, at least theoretically, electrons can lose their electric charge or shed a quantum property called spin when they hop between two quantum materials. With the Sloan Research Fellowship, Barkeshli hopes to continue studying the novel ways that electrons and other, more exotic particles behave at these interfaces. This research could uncover new ways of building quantum computers that are virtually immune to noise, and has led to experimental proposals that could soon be tested in the lab.Barkeshli has authored more than 35 peer-reviewed journal articles. Before joining the UMD faculty in 2016, Barkeshli worked as a postdoctoral researcher at Microsoft Research’s Station Q (2013-2016) and at Stanford University (2010-2013). He earned a bachelor’s degree in physics and a second bachelor’s degree in electrical engineering and computer science from the University of California, Berkeley, in 2004. He received his doctoral degree in physics from the Massachusetts Institute of Technology in 2010.Barkeshli joins the list of 39 current UMD College of Computer, Mathematical, and Natural Sciences faculty members who have received Sloan Research Fellowships.The two-year $65,000 Sloan Research Fellowships are awarded to U.S. and Canadian researchers in the fields of chemistry, computer science, economics, mathematics, computational and evolutionary molecular biology, neuroscience, ocean sciences, and physics. Candidates must be nominated by their fellow scientists and winning fellows are selected by independent panels of senior scholars on the basis of each candidate’s independent research accomplishments, creativity and potential to become a leader in his or her field. “The Sloan Research Fellows represent the very best science has to offer,” said Adam Falk, president of the Alfred P. Sloan Foundation. “The brightest minds, tackling the hardest problems, and succeeding brilliantly—Fellows are quite literally the future of twenty-first century science.”
February 13, 2018 | People News

JQI Fellow Vladimir Manucharyan receives DARPA 2017 Young Faculty Award

JQI Fellow Vladimir Manucharyan has recently received the 2017 Young Faculty Award (YFA) from the Defence Advanced Research Projects Agency (DARPA) to support his research on topological superconductivity. According to DARPA, the YFA program seeks to “identify and engage rising research stars in junior faculty positions at U.S. academic institutions”. During the 2-year support period, DARPA grants awardees with mentoring and financial support.Manucharyan plans to use the award to implement superconducting semiconductors, novel devices that could become the building blocks of topological quantum computers. If the project is successful, DARPA will provide continuing support. Superconductivity arises when certain materials—usually at very low temperatures—lose all of their electric resistivity. This phenomenon occurs because electrons pair up to freely flow within the material due to an attractive interaction between them. Usually, semiconductors—substances that partially conduct electricity—don’t exhibit superconductivity, because their electrons are not close enough to each other to pair up. However, semiconductors are beneficial in other ways, and one of their biggest advantages is the ability to externally control their resistivity with an electric field. Manucharyan plans to create multi-terminal Josephson junctions, a novel device which incorporates the features of both superconductors and semiconductors. “It's a device where a central part consists of a small semiconducting region and more than two superconducting leads are connected to it,” he explains. Theory predicts that the nearby superconducting leads should induce superconductivity in the semiconducting region.Such devices could serve as superconducting transistors with reduced power loss and less heat dissipation, a major advance for the semiconductor chip technology. The multi-terminal Josephson junctions could also be used to study topological effects in exotic materials and to even model physics in more than three dimensions. Because of its topological properties, the novel device could form the basic units of topological quantum computers, paving the way towards a practical quantum computer.
February 12, 2018 | PFC | Research News

New hole-punched crystal clears a path for quantum light

Optical highways for light are at the heart of modern communications. But when it comes to guiding individual blips of light called photons, reliable transit is far less common. Now, a collaboration of researchers from the Joint Quantum Institute (JQI), led by JQI Fellows Mohammad Hafezi and Edo Waks, has created a photonic chip that both generates single photons, and steers them around. The device, described in the Feb. 9 issue of Science, features a way for the quantum light to seamlessly move, unaffected by certain obstacles."This design incorporates well-known ideas that protect the flow of current in certain electrical devices," says Hafezi. "Here, we create an analogous environment for photons, one that protects the integrity of quantum light, even in the presence of certain defects."The chip starts with a photonic crystal, which is an established, versatile technology used to create roadways for light. They are made by punching holes through a sheet of semiconductor. For photons, the repeated hole pattern looks very much like a real crystal made from a grid of atoms. Researchers use different hole patterns to change the way that light bends and bounces through the crystal. For instance, they can modify the hole sizes and separations to make restricted lanes of travel that allow certain light colors to pass, while prohibiting others.
January 12, 2018 | PFC | Research News

Light may unlock a new quantum dance for electrons in graphene

A team of researchers has devised a simple way to tune a hallmark quantum effect in graphene—the material formed from a single layer of carbon atoms—by bathing it in light. Their theoretical work, which was published recently in Physical Review Letters, suggests a way to realize novel quantum behavior that was previously predicted but has so far remained inaccessible in experiments."Our idea is to use light to engineer these materials in place," says Tobias Grass, a postdoctoral researcher at the Joint Quantum Institute (JQI) and a co-author of the paper. "The big advantage of light is its flexibility. It’s like having a knob that can change the physics in your sample."
January 12, 2018 | PFC | People News

Former JQI researcher wins Chilean L'Oréal-UNESCO Award For Women in Science

Carla Hermann Avigliano, a former postdoc with JQI Fellow Paul Lett, is one of two women scientists to receive the Chilean L'Oréal-UNESCO Award For Women in Science. She was selected for the prize out of 77 applications and cited for her research achievements during her early career. The award is part of a larger program that aims to internationally recognize women researchers in science and operates throughout the world. In Chile, 21 women from various areas of science such as physics, chemistry, biology, nursing, geology, forestry, biotechnology and ecology, among others, have received the prize since 2007. 
December 21, 2017 | Podcast

Ancient timekeeping with a modern twist

Trey Porto, a NIST physicist and Fellow of the Joint Quantum Institute, spends his days using atoms and lasers to study quantum physics. But even outside of the lab, he views the world as one great physics problem to tackle. So one morning when he spotted some sunlight dancing across his wall, he couldn’t help but dive in and calculate its movements. He then took his project a step further and began constructing a sundial. Emily sat down with Porto to hear about his clock-making hobby and how today’s time-keeping differs from its ancient counterparts. This episode of Relatively Certain was produced by Emily Edwards and Chris Cesare. It features music by Dave Depper and Poddington Bear. Relatively Certain is a production of the Joint Quantum Institute, a research partnership between the University of Maryland and the National Institute of Standards and Technology, and you can find it on iTunes, Google Play or Soundcloud.
December 4, 2017 | PFC | Research News

Narrow glass threads synchronize the light emissions of distant atoms

If you holler at someone across your yard, the sound travels on the bustling movement of air molecules. But over long distances your voice needs help to reach its destination—help provided by a telephone or the Internet. Atoms don’t yell, but they can share information through light. And they also need help connecting over long distances.Now, researchers at the Joint Quantum Institute (JQI) have shown that nanofibers can provide a link between far-flung atoms, serving as a light bridge between them. Their research, which was conducted in collaboration with the Army Research Lab and the National Autonomous University of Mexico, was published last week in Nature Communications. The new technique could eventually provide secure communication channels between distant atoms, molecules or even quantum dots. 
November 29, 2017 | PFC | Research News

Quantum simulators wield control over more than 50 qubits

Two independent teams of scientists, including one from the Joint Quantum Institute, have used more than 50 interacting atomic qubits to mimic magnetic quantum matter, blowing past the complexity of previous demonstrations. The results appear in this week’s issue of Nature.As the basis for its quantum simulation, the JQI team deploys up to 53 individual ytterbium ions—charged atoms trapped in place by gold-coated and razor-sharp electrodes. A complementary design by Harvard and MIT researchers uses 51 uncharged rubidium atoms confined by an array of laser beams. With so many qubits these quantum simulators are on the cusp of exploring physics that is unreachable by even the fastest modern supercomputers. And adding even more qubits is just a matter of lassoing more atoms into the mix. 

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