Chicago Quantum Exchange Profile: Jennifer Choy

profile photo of Jen Choy

WQI’s Jennifer Choy was recently featured as part of a series of profiles of scientists and engineers from across the Chicago Quantum Exchange member institutions. This post was originally published by CQE


Jennifer Choy is an assistant professor of engineering physics at the University of Wisconsin–Madison who studies quantum sensing and nanophotonics. She aspires to be a great mentor to undergraduate and graduate students and encourages students to study quantum science, even if they don’t plan to go into the field.

Tell us about what you’re working on now.

We are developing miniaturized and mobile quantum sensors and engineering quantum platforms to improve their sensing performance. We are interested in two material platforms in particular: neutral atoms and solid-state color centers. Our group is applying techniques in nanoscale optics and integrated photonics to exert precise control over atom-photon interactions and miniaturize atomic sensors. We are currently developing chip-scale, near-infrared polarization optics for alkali vapor magnetometers, which could enable compact, sensitive magnetic-field-imaging devices.

How does UW–Madison help advance your work?

UW-Madison has a strong research community in quantum computing and sensing platforms and is supported by groups across many science and engineering departments. It has been very inspiring and exciting to establish relationships and collaborations with top-notch quantum researchers at UW-Madison and in the Midwest under the Wisconsin Quantum Institute and the Chicago Quantum Exchange.

How did you become interested in quantum research?

As a freshman in the Nuclear Science and Engineering department at MIT, I joined David Cory’s group, working on using liquid-state nuclear magnetic resonance as a testbed for quantum computing. I think how someone gravitates toward a field depends greatly on formative experiences and environments. I had no prior knowledge in quantum physics, but graduate students in the group were very supportive and David always graciously answered questions and offered advice, even long after I graduated. I aspire to being able to foster a similar mentoring approach and attitude.

What does the future hold for quantum technology? 

The use of quantum science in sensors and sensing brings a set of tools that can promise greater sensitivity and accuracy than conventional technologies, some of which are already in use. However, to make the next leap to other practical applications outside of the lab, a combination of fundamental science research and engineering will be needed to realize functional and robust sensor systems. Broader applications would include quantum accelerometers, gyroscopes, and clocks that can provide accurate navigation solutions without the need for GPS.

Quantum technology has a workforce shortage. What would you say to a young person who is interested in studying quantum information science?

I think part of the excitement of working in the field of quantum information science is that it offers interesting research directions in almost every science and engineering discipline. Developing quantum technologies requires partnership among academia, national labs, and industry. With several federally funded quantum initiatives, job opportunities will likely open up in all these sectors.

As someone who worked in industry (as a scientist at Draper Laboratory), what I really appreciated about my training in quantum research is that I was able to apply my skills to other unrelated fields, which were just as interesting and fulfilling. Therefore, I think a quantum workforce will generate well-rounded talents that will also benefit other industries.

MSPQC student Jacques Van Damme publishes first-author paper with WQI faculty

a group of students in front of a white board with physics equations on it

Congrats to Jacques Van Damme, a member of the first class of MSPQC students who graduated this past August, on his first-author publication! The study, published in Physical Review A, is titled, “Impacts of random filling on spin squeezing via Rydberg dressing in optical clocks.” Co-authors include WQI faculty members Mark Saffman, Maxim Vavilov, and senior author Shimon Kolkowitz. | Link to the PRA publication

Shimon Kolkowitz awarded two grants to push optical atomic clocks past the standard quantum limit

a metallic chamber with a blue fluorescence glowing orb of atoms in the center

Optical atomic clocks are already the gold standard for precision timekeeping, keeping time so accurately that they would only lose one second every 14 billion years. Still, they could be made to be even more precise if they could be pushed past the current limits imposed on them by quantum mechanics.

With two new grants from the U.S. Army Research Office, an element of the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory, UW–Madison physics professor Shimon Kolkowitz proposes to introduce quantum entanglement — where atoms interact with each other even when physically distant — to optical atomic clocks. The improved clocks would allow researchers to ask questions about fundamental physics, and they have applications in improving quantum computing and GPS.

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WQI researchers awarded DOE Quantum Information Science grant

Three UW–Madison physics professors and their colleagues have been awarded a U.S. Department of Energy (DOE) High Energy Physics Quantum Information Science award for an interdisciplinary collaboration between theoretical and experimental physicists and experts on quantum algorithms.

The grant, entitled “Detection of dark matter and neutrinos enhanced through quantum information,” will bring a total of $2.3 million directly to UW-Madison. Physics faculty include principal investigator Baha Balantekin as well as Mark Saffman, and Sue Coppersmith. Collaborators on the grant include Kim Palladino at the University of Oxford, Peter Love at Tufts University, and Calvin Johnson at San Diego State University.

With the funding, the researchers plan to use a quantum simulator to calculate the detector response to dark matter particles and neutrinos. The simulator to be used is an array of 121 neutral atom qubits currently being developed by Saffman’s group. Much of the research plan is to understand and mitigate the behavior of the neutral atom array so that high accuracy and precision calculations can be performed. The primary goal of this project is to apply lessons from the quantum information theory in high energy physics, while a secondary goal is to contribute to the development of quantum information theory itself.

Surprising communication between atoms could improve quantum computing

A dark room with pink-hued lasers reflecting off of mirrors
In their experiments, UW–Madison physicists led by Deniz Yavuz immobilized a group of rubidium atoms by laser-cooling them to just slightly above absolute zero. Then, they shined a laser at rubidium’s excitation wavelength to energize electrons. | Photo provided by Yuvuz Lab

A group of University of Wisconsin­–Madison physicists has identified conditions under which relatively distant atoms communicate with each other in ways that had previously only been seen in atoms closer together — a development that could have applications to quantum computing.

The physicists’ findings, published Oct. 14 in the journal Physical Review A, open up new prospects for generating entangled atoms, the term given to atoms that share information at large distances, which are important for quantum communications and the development of quantum computers.

“Building a quantum computer is very tough, so one approach is that you build smaller modules that can talk to each other,” says Deniz Yavuz, a UW–Madison physics professor and senior author of the study. “This effect we’re seeing could be used to increase the communication between these modules.”

The scenario at hand depends on the interplay between light and the electrons that orbit atoms. An electron that has been hit with a photon of light can be excited to a higher energy state. But electrons loathe excess energy, so they quickly shed it by emitting a photon in a process known as decay. The photons atoms release have less energy than the ones that boosted the electron up — the same phenomenon that causes some chemicals to fluoresce, or some jellyfish to have a green-glowing ring.

“Now, the problem gets very interesting if you have more than one atom,” says Yavuz. “The presence of other atoms modifies the decay of each atom; they talk to each other.”

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Two WQI students named to QISE-NET’s Fall 2020 cohort

split screen profile photo of Vincent Liu and Cecilia Vollbrecht

Two WQI graduate students, Chuanhong (Vincent) Liu (McDermott Group) and Cecilia Vollbrecht (Goldsmith Group), have had their projects awarded funding through QISE-NET, the Quantum Information Science and Engineering Network. Run through the University of Chicago, QISE-NET is open to any student pursuing an advanced degree in any field of quantum science. Liu, Vollbrecht, and other students in their cohort earn up to three years of support, including funding, mentoring and training at annual workshops. All awardees are paired with a mentoring QISE company or national lab, at which they will complete part of their projects. Liu and Vollbrecht explain their projects below.

Profile photo of Vincent Liu
Chuanhong (Vincent) Liu
Chuanhong (Vincent) Liu | McDermott Group | Mentoring partner: NIST

“The Single Flux Quantum (SFQ) digital logic family has been proposed as a scalable approach for the control of next-generation multiqubit arrays. With NIST’s strong track record in the field of SFQ digital logic and the expertise of McDermott’s lab in the superconducting qubit area, we expect to achieve high fidelity SFQ-based qubit control. The successful completion of this research program will represent a major step forward in the development of a scalable quantum-classical interface, a critical component of a fully error-corrected fault-tolerant quantum computer.”

profile photo of Cecilia Vollbrecht
Cecilia Vollbrecht
Cecilia Vollbrecht | Goldsmith Group | Mentoring Partner: NIST

“The goal of my proposal is to develop a coupled cavity array that will allow us to simulate complex quantum phenomena. With the partnership between NIST and Prof. Goldsmith’s group I can combine the expertise of both groups to create an array where we characterize energy transfer and loss pathways, couplings, and coherence. The knowledge gained from these experiments will help to make a highly controlled cavity quantum electrodynamics platform.”

Q-NEXT collaboration awarded National Quantum Initiative funding

The University of Wisconsin–Madison solidified its standing as a leader in the field of quantum information science when the U.S. Department of Energy (DOE) and the White House announced the Q-NEXT collaboration as a funded Quantum Information Science Research Center through the National Quantum Initiative Act. The five-year, $115 million collaboration was one of five Centers announced today.

Q-NEXT, a next-generation quantum science and engineering collaboration led by the DOE’s Argonne National Laboratory, brings together nearly 100 world-class researchers from three national laboratories, 10 universities including UW–Madison, and 10 leading U.S. technology companies to develop the science and technology to control and distribute quantum information.

“The main goals for Q-NEXT are first to deliver quantum interconnects — to find ways to quantum mechanically connect distant objects,” says Mark Eriksson, the John Bardeen Professor of Physics at UW–Madison and a Q-NEXT thrust lead. “And next, to establish a national resource to both develop and provide pristine materials for quantum science and technology.”

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Shimon Kolkowitz earns 2019 Packard Fellowship

announcement slide by Packard foundation congratulating Shimon Kolkowitz on the Fellowship

Shimon Kolkowitz, a University of Wisconsin–Madison assistant professor of physics, has been selected as one of 22 members of the 2019 class of Packard Fellows for Science and Engineering.

The fellowship, awarded to early-career scientists from across the U.S., provides $875,000 of funding over five years. Kolkowitz will use the funds to develop his research program in ultra-precise atomic clocks, which he will use to investigate such fundamental aspects of physics as the relationship between quantum mechanics and gravity and the nature of dark matter.

Read the full story here.

Chicago Quantum Summit to gather international experts

abstract graphic of atoms

Top experts in quantum technology from around the globe — including experts from the Wisconsin Quantum Institute — will gather at the University of Chicago on Oct. 25 to discuss the future of quantum information science and strategies to build a quantum workforce.

The second annual Chicago Quantum Summit, hosted by the Chicago Quantum Exchange, will engage scientific and government leaders and the industries that will drive the applications of emerging quantum information science.

Read the full story here. 

WQI scientists earn grant to improve materials for quantum sensing, computing

four panels of images showing quantum sensors and qubits used in the lab and to develop quantum computers

Researchers at the Wisconsin Quantum Institute (WQI) have been awarded a US Department of Energy grant to study the noise that hampers advances in quantum systems, including quantum computers.

The three-year, $4 million funding will allow the researchers to apply emerging tools to identify new materials and fabrication methods that can improve the performance of these systems.

“All of physics is quantum on some level, and quantum systems let you understand how physics works when you get to the cleanest, smallest, most isolated systems,” says Shimon Kolkowitz, assistant professor of physics at the University of Wisconsin–Madison and lead investigator of the grant. “We think that quantum computing, and quantum technologies more generally, are a really promising area of technological development and research.”

Quantum systems — which make use of single atoms or electrons and the quantum mechanical properties that govern them — have the potential to push boundaries in such areas as computing, precision sensing, and secure communications.

Quantum computers, for example, allow scientists to simulate quantum mechanics in ways that classical computers cannot. But, the computing power of quantum computers has not yet exceeded classical ones.

a grayscale image of a scanning electron micrograph of one of the double quantum dot qubits
A scanning electron microscope image of a gate-defined double quantum dot qubit fabricated by the Eriksson group.

A limiting factor in quantum computing power is the number of qubits, or quantum bits, that can be strung together. Like bits in a classic computer, the more qubits in a quantum computer, the more the computing power. And the limiting factor in how many qubits can be connected with each other while remaining in the fragile quantum states required to perform a computation — called “coherence”  in quantum lingo — is their resistance to external environmental factors, or “noise” that may cause them to “decohere.”

However, researchers have found that the materials used to make the qubits themselves generate a lot of this noise.

“People for quite a while have seen this noise, treated it as a fact of nature, and tried to design around it. But no one really knows what it is or how to get rid of it,” Kolkowitz says. “Even more fundamentally than just understanding or reducing this noise, we think that if you can reduce or ultimately eliminate this noise, it actually opens up the design space for the kinds of qubits you can build, and that will make it much easier to wire qubits together.”

With the DOE funding, Kolkowitz, along with colleagues at WQI and the Livermore National Laboratory, seeks to first identify the nature of the noise and how specific materials contribute to it, and then to develop ways to reduce it.

small white dots, representing single atom defects, are visible in a dark purplish background that is from a diamond
Atom-size quantum defects in a diamond, imaged using a confocal microscope in the Kolkowitz lab.

Work in Kolkowitz’s group, as well as that of Victor Brar, assistant professor of physics and co-investigator on the grant, has led to the development of quantum sensors that allow the researchers to characterize things like magnetic fields at the nanometer scale, or to see how single atoms are arranged in various materials. Part of the DOE funding will be used to continue improving these sensors.

Kolkowitz and Brar then want to use their sensors to identify the noise affecting qubits designed by UW quantum computing researchers Mark Eriksson and Robert McDermott.

“And then we can work in a feedback loop, where, for example, Robert McDermott makes samples and characterizes their performance, then we study the noise limiting that performance with these quantum and nanoscale probes to figure out what’s happening on the microscopic scale,” Kolkowitz says. “Then, we give that information to our theory collaborators here and at Livermore who build models and simulations based on what we’ve measured. And then Robert can use what we’ve learned to design and make new samples to see if we’ve improved on these issues.”

scanning tunneling micrograph showing graphene with a single atomic defect as a white dot in the center.
An image taken with a scanning tunneling microscope of a single atomic defect in graphene

Trying to identify sources of this noise is nothing new, but what Kolkowitz finds most promising about the work funded through this grant is the development and application of new sensing technologies.

“These emerging tools that use quantum states and quantum systems themselves should give us access to the origins and behavior of noise in quantum platforms on scales that haven’t been accessible before,” Kolkowitz says.

Other WQI members who are co-investigators on the grant include Jennifer Choy, Laura Faoro, Mark Friesen, and Alex Levchenko.