QTC, NRL Announce New Partnership

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Category: Department News

Published: Tuesday, September 01 2020 12:21

The Quantum Technology Center (QTC)—a joint venture between the University of Maryland’s A. James Clark School of Engineering and the College of Computer, Mathematical, and Natural Sciences (CMNS)—entered into an Education Partnership Agreement with the U.S. Naval Research Laboratory (NRL) to identify and pursue opportunities related to quantum technology research. 

The new partnership with NRL is specifically focused on advancing quantum technology for applications that are relevant to the warfighter, and will involve exchanges of expertise and samples; collaborations in experimental, theoretical, and educational work; mutual research proposals; and the exchange of researchers.

"The University of Maryland is excited to partner with the U.S. Naval Research Laboratory to explore the diverse applications of quantum technologies," said Dr. Laurie Locascio, vice president for research at UMD.

Launched in 2019, QTC capitalizes on the university’s strong research programs and partnerships in quantum science and systems engineering, and pursues collaborations with industry and government labs to help take promising quantum advances from the lab to the marketplace. QTC has a long rooted history of working with the Department of Defense Research Labs, as QTC’s founding partner is the Combat Capabilities Development Command (CCDC) Army Research Laboratory.

Quantum technology is making a huge impact in industry and government sectors, and the partnership between UMD and NRL will help move critical technologies forward.

“Research in quantum information science and technologies has the potential to bring new warfighting capabilities to the U.S. Navy and Marine Corps as well as to provide benefits to society at large,” said Gerald M. Borsuk, Ph.D., associate director of research for the systems directorate at NRL. “We are excited about working with the Quantum Technology Center at the University of Maryland to advance leading edge quantum technologies. We share a mutual commitment to providing students and faculty with high quality educational outreach, knowledge sharing, and research opportunities.”

Both the QTC and NRL aim to build and improve STEM educational and research capacities, and provide resources and equipment for research activities. There have been collaborations and joint proposals between these groups in recent years, particularly in work on solid state systems. Moving forward, future interactions are expected to involve work on quantum dots and defects, and on systems for quantum memory and networking, with a goal to advance the scaling and integration of quantum technologies. 

“Quantum technology is developing rapidly, and many organizations are quickly getting involved. We are thrilled to collaborate with NRL to strengthen the current research and training activities within QTC, expand our research in areas such as machine learning and quantum networking, and notably, accelerate realization of the quantum internet,” said Ronald Walsworth, founding director of the QTC and UMD professor of electrical and computer engineering and physics. Mohammad Hafezi, Alicia Kollár, Norbert Linke, Chris Monroe and Steve Rolston are also QTC members.

The partners are also interested in collaborating on technologies associated with creating and implementing a quantum internet network. This research would involve quantum memory, quantum repeaters and routers, as well as associated classical network theory and associated implementations. Another area of interest to both QTC and NRL include defect states in semiconductors, such as diamond and silicon carbide, for opportunities in networking and in sensing, particularly magnetometry.

“QTC translates quantum science into new capabilities and technologies for real world applications. This partnership gives QTC, UMD and the Navy the opportunity for joint research to advance quantum technology for the Navy and will help prepare a workforce trained in this critical area,” said Walsworth.

Arnold J. Glick, 1931- 2020

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Category: Department News

Published: Thursday, August 27 2020 00:01

Professor Emeritus Arnold J. Glick died on Aug. 16, after falling ill two days earlier.

Glick was the only child of immigrants who met and married in Brooklyn and operated a small clothing store. His early interest and acuity in math and science led to acceptance into New York’s renowned and specialized Stuyvesant High School.

After graduation, Glick moved to Israel to work at Kibbutz Gal On at a time of scarcity in the new nation. Undernourished and in receipt of a U.S. Army draft notice, he returned home and was sent to the 82^nd Airborne Division at Fort Bragg, North Carolina, where he worked on radio communications during the Korean War. Near the end of his service, he was charged in a McCarthy-era military court with being a communist. Eventually, it was revealed that the accusation stemmed from his father’s attendance at a lecture by the writer Howard Fast.  Once Glick was cleared and honorably discharged, he earned his bachelor’s degree in physics from Brooklyn College and entered the UMD physics graduate program under the tutelage of Richard A. Ferrell, studying how electrons in metals respond when heated or subjected to electric fields.

Glick received his doctorate in 1961 and accepted a postdoctoral position in nuclear physics at the Weizmann Institute of Science in Israel. There he did his most recognized work, on many-particle phenomena, including a paper with well over 1,000 citations. He was then invited to join the UMD physics faculty by then-chair John Sampson Toll.

Glick developed a new major focus on the properties of 1D (one-dimensional) polyacetylene, an intrinsically conducting polymer invented in 1958; interest flourished after a landmark 1979 paper showing that it supports solitons. Collaborating with him was postdoc Garnett W. Bryant, now Group Leader of the Atomic-Scale Device Group at NIST. “It was very fun at the time working with Arnie on these projects and having a chance, for the first time, to experience the excitement of working in a high profile, emerging area of physics,” said Bryant.

Collaborating with his student Shyamalendu M. Bose and Prof. Angelo Bardasis, Glick calculated quasiparticle damping in a free-electron gas. With George A Ausman, Jr., he studied many-body effects that occurred near the threshold for core excitations in metals caused by soft x-rays.  Other work included Auger emission spectra in metals with student Amy Liu Hagen, many-body effects in core-level spectroscopy with student Harvey Gotts, fluctuation-induced tunneling in a 1D tight-binding model with student Ronald J. Cohen and soliton contributions with student David M. Mackie.

Glick’s student William R. Bandy, the department’s 2012 Distinguished Alumnus, studied electron tunneling and diagonal disorder with Glick. Bandy recalled “sitting in his office talking through my latest technical challenge, hearing about the latest engine replacement for his aging VW bus camper that he drove to Aspen every summer…. he was always giving me recommendations for good hiking trails in the region.”

Glick's parents taught him to hike as a youngster. The days spent ascending New Hampshire's White Mountains and snacking on mulberries inspired a love of nature that lasted throughout his lifetime.    

Another keen interest was folk dancing, which he enjoyed for decades. Glick also availed himself of UMD’s breadth and studied modern dance, ballet, scuba diving, squash, movies and sculpture. He and his wife Rachel were frequent visitors at the department’s special lectures, retreats and retirement celebrations and enjoyed lectures and performances at the Clarice Smith Performing Arts Center.

In addition to Rachel, survivors include his first wife, Nevet Montgomery; daughters Jody Glick, Jeri Glick (Charles Anderson), and Ora DeMorrow (Shannon Lynch); and four grandchildren.

His obituary in the Greenbelt News Review is here: https://greenbeltnewsreview.com/issues/GNR20200827.pdf

Arnie Glick and Rick Greene at a holiday gathering.

Richard Prange, Ching-Ping Wang, Arnie Glick and Victor Yakovenko.

Physics faculty, 1970s.

Physics faculty, 1977.

Physics faculty, 1975.

UMD Researchers Included in DoE Quantum Project

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Category: Research News

Published: Wednesday, August 26 2020 05:33

Quantum Computers Do the (Instantaneous) Twist

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Category: Research News

Published: Wednesday, August 19 2020 05:33

Regardless of what makes up the innards of a quantum computer, its speedy calculations all boil down to sequences of simple instructions applied to qubits—the basic units of information inside a quantum computer.

Whether that computer is built from chains of ions, junctions of superconductors, or silicon chips, it turns out that a handful of simple operations, which affect only one or two qubits at a time, can mix and match to create any quantum computer program—a feature that makes a particular handful “universal.” Scientists call these simple operations quantum gates, and they have spent years optimizing the way that gates fit together. They’ve slashed the number of gates (and qubits) required for a given computation and discovered how to do it all while ensuring that errors don’t creep in and cause a failure.

Now, researchers at JQI have discovered ways to implement robust, error-resistant gates using just a constant number of simple building blocks—achieving essentially the best reduction possible in a parameter called circuit depth. Their findings, which apply to quantum computers based on topological quantum error correcting codes, were reported in two papers published recently in the journals Physical Review Letters(link is external) and Physical Review B(link is external), and expanded on in a third paper published earlier in the journal Quantum(link is external).Unlike other kinds of quantum computers, quantum computers built atop topological error correction smear a single qubit’s worth of information out among a network of many qubits. (Credit: Gerd Altmann/Pixabay)

Circuit depth counts the number of gates that affect each qubit, and a constant depth means that the number of gates needed for a given operation won’t increase as the computer grows—a necessity if errors are to be kept at bay. This is a promising feature for robust and universal quantum computers, says Associate Professor Maissam Barkeshli. 

“We have discovered that a huge class of operations in topological states of matter and topological error correcting codes can be implemented via constant depth unitary circuits,” says Barkeshli, who is a member of the Joint Quantum Institute and the Condensed Matter Theory Center at UMD.

Unlike other kinds of quantum computers, quantum computers built atop topological error correction—which so far have only been studied theoretically—don’t store information in individual physical qubits. Instead, they smear a single qubit’s worth of information out among a network of many qubits—or, more exotically, across special topological materials.

This information smearing provides resilience against stray bits of light or tiny vibrations—quantum disturbances that may cause errors—and it allows small errors to be detected and then actively corrected during a computation. It’s one of the main advantages that quantum computers based on topological error correction offer. But the advantage comes at a cost: If noise can’t get to the information easily, neither can you.

Until now it seemed that operating such a quantum computer required small, sequential changes to the network that stores the information—often depicted as a grid or lattice in two dimensions. In time, these small changes add up and effectively move one region of the lattice in a loop around another region, leaving the network looking the same as when it started.

These transformations of the network are known as braids because the patterns they trace out in space and time look like braided hair or a plaited loaf of bread. If you imagine stacking snapshots of the network up like pancakes, they will form—step by step—an abstract braid. Depending on the underlying physics of the network—including the kinds of particles, called anyons, that can hop around on it—these braids can be enough to run any quantum program.

In the new work, the authors showed that braiding can be accomplished almost instantaneously. Gone are the knotted diagrams, replaced by in-situ rearrangements of the network.

“It was kind of a textbook dogma that these braids can only be done adiabatically or very slowly so as to avoid creating errors in the process,” says Guanyu Zhu, a former JQI postdoctoral researcher who is currently a research staff member at the IBM Thomas J. Watson Research Center. “However, in this work, we realized that instead of slowly moving regions with anyons around each other, we could just stretch or squeeze the space between them in a constant number of steps.”

The new recipe requires two ingredients. One is the ability to make local modifications that reconfigure the interactions between the physical qubits that make up the network. This part isn’t too different from what ordinary braiding requires, but it is assumed to happen in parallel across the region being braided. The second ingredient is the ability to swap the information on physical qubits that are not close to each other—potentially even at opposite corners of the braiding region.

Networks of qubits (represented by black dots in the image on the right) are deformed in order to braid two regions (represented by red and blue dots) around each other. These images show two intermediate stages of the process. Images provided courtesy of the authors.

Networks of qubits (represented by black dots in the image on the right) are deformed in order to braid two regions (represented by red and blue dots) around each other. These images show two intermediate stages of the process. Images provided courtesy of the authors.

This second requirement is a big ask for some quantum computing hardware, but the authors say that there are systems that could naturally support it.

“A variety of experimental platforms with long-range connectivity could support our scheme, including ion traps, circuit QED systems with long transmission-line resonators, modular architectures with superconducting cavities, and silicon photonic devices,” says Zhu. “Or you could imagine using platforms with movable qubits. One can think of such platforms as fluid quantum computers, where qubits can freely flow around via classical motion.”

In the paper in Physical Review Letters, the authors provided explicit instructions for how to achieve their instantaneous braids in a particular class of topological quantum codes. In the Physical Review B and Quantum papers, they extended this result to a more general setting and even examined how it would apply to a topological code in hyperbolic space (where, additionally, adding a new smeared out qubit requires adding only a constant number of physical qubits to the network).

The authors haven’t yet worked out how their new braiding techniques will mesh with the additional goals of detecting and correcting errors; that remains an open problem for future research.

“We hope our results may ultimately be useful for establishing the possibility of fault-tolerant quantum computation with constant space-time overhead,” says Barkeshli.

Original story by Chris Cesare: https://jqi.umd.edu/news/quantum-computers-do-instantaneous-twist

In addition to Barkeshli and Zhu, the three papers had one additional co-author: Ali Lavasani, a JQI graduate fellow and physics graduate student at UMD.