Quantum Science

Matt Otten part of project to develop novel quantum sensor

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This post is adapted from one originally published by Fermilab

Fermilab is finalizing a partnership with Diraq and several universities — including the University of Wisconsin–Madison — for the Quandarum project. The project team intends to combine extreme environment electronics and silicon spin qubits to develop a quantum sensor that could profoundly impact the field of high-energy physics.

Researchers at the Department of Energy’s Fermi National Accelerator Laboratory, along with scientists and engineers at Diraq, University of Wisconsin–Madison, University of Chicago and Manchester University, have proposed the development of a quantum sensor made of quantum bits called spin qubits in silicon to probe beyond Standard Model physics.

hands from an unidentified individual hold a metal pancake-like object with some tech-y designed on it. The object is roughly a foot in diameter.
The scalability advantages available via silicon CMOS wafer manufacture deliver significant promise for Diraq’s patented spin-based quantum dot technology. Credit: Diraq

By placing many spin qubits together on a chip to form a sensor, the researchers seek to enable scientists to tease out even the faintest signals from the cosmos. Such a sensor could potentially be used to detect axions, hypothetical particles that some scientists believe comprises dark matter.

Led by Fermilab, the Quandarum project is one of 25 projects funded for a total of $71 million by the DOE program Quantum Information Science Enabled Discovery. The QuantISED program supports innovative research at national laboratories and universities that applies quantum technologies to use for fundamental science discovery.

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Matthew Otten

“The project is looking at how quantum sensors might be used for high energy physics applications, specifically in axion detection,” says UW–Madison physics professor Matt Otten. “[My partners] know much more about axion detection, I happen to not know about axions, and that’s why we’re a team.”

With this award, researchers plan to develop a novel sensor. To do so, they plan to bring together for the first time two specialized technologies: spin qubits in silicon and cryogenic “skipper” analog-to-digital converter circuits used for the readout of dark matter detectors.

Silicon spin-based quantum sensors can provide a powerful platform for testing theories around dark matter because they can exploit quantum interactions to increase sensitivity and explore the limits of what scientists understand about high-energy physics.

“My group’s part of it is, given these large silicon qubit arrays, we might utilize the fact that they are essentially quantum computers,” Otten says. “We’re going to be studying entanglement enhanced quantum sensing, either through the use of error correcting code or through novel entangled states.”

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U.S. Cyber Command visit highlights UW–Madison’s leadership in cyber research and education

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UW–Madison plays a leading role as a research and education partner for national cybersecurity. It reinforced this commitment recently by welcoming to campus a delegation from the United States Cyber Command (USCYBERCOM), which is responsible for the Department of Defense’s cyberspace capabilities.

Read the full article at: https://news.wisc.edu/u-s-cyber-command-visit-highlights-uw-madisons-leadership-in-cyber-research-and-education/

Welcome, Prof. Britton Plourde!

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Britton Plourde (credit: Isabelle Delfosse, L&S)

Condensed matter experimentalist Britton Plourde received his bachelor’s in physics and music performance from the University of Michigan. He then went to grad school at UIUC, earning a PhD in physics and a master’s in music performance. He completed a postdoc at UC-Berkeley, then began as an assistant professor of physics at Syracuse University in 2005, moving up the ranks to full professor there. In Fall 2024, Plourde joined the UW–Madison physics department as a full professor. He is joining the department on a half-time appointment; for the other half, he will be working at Qolab, a quantum computing startup company based in Madison.

 Please give an overview of your research.

I work on superconducting quantum circuits. We make microfabricated superconducting circuits that have what are called Josephson tunnel junctions in them. And one of the biggest things we use these for is making qubits. We study all of the various physics related to how qubits work, what limits their performance, and ways to make them perform better so you could eventually build a practical, large-scale quantum computer. My research is similar to Robert McDermott’s and Roman Kuzmin’s.

What are the first one or two projects that you will have your group working on or continuing to work on when you arrive in Madison?

The company I’m working with, Qolab, is focused on building a quantum computer. My academic research lab at the university will be focused on fundamental physics related to operation of qubits, including the individual components of qubits like the Josephson junctions and to different processes that limit the performance of qubits. At the same time, the company is really focused on the technology of fabricating lots of qubits in a uniform, reproducible way and building them into a quantum computer.

In my group, a significant focus is going to be on understanding quasiparticles in superconducting qubits and how they impact the behavior of those qubits. Quasiparticles are electronic excitations above the superconducting ground state. The superconducting ground state is important because it doesn’t have any dissipation. But these quasiparticles are dissipative, and they can degrade the performance of a superconducting circuit. There are various things that can generate the quasiparticles, but one of them is radioactivity: background radiation from radioactive contaminants in the lab or from cosmic rays. My group is going to continue spending time on understanding the physics of those processes and coming up with ways to try to mitigate their effects to make qubits that are more immune to quasiparticles.

We’re also hoping to study quasiparticle physics in qubits for the completely opposite reason: instead of trying to mitigate the effects of quasiparticles to make better qubits, it’s to amplify the effects of quasiparticles to make better detectors, potentially to detect dark matter particles. Robert and I are co-principal investigators with some particle physics collaborators on two Department of Energy proposals for this work that we recently submitted. This work hasn’t been funded yet, but if it is, it is going to be a new and interesting research direction in both of our groups.

What attracted you to Madison and the university?

It’s a great department. I’ve known it for a long time because I collaborated with Robert almost as long as he’s been there. I’ve visited a lot over the years, and I like the area and the city. The university has made an impressive investment in quantum information science, and they’re a real leader in that area and have research strengths across multiple different qubit technologies, both experimentally and with a strong team of theorists working on different aspects of quantum information science and condensed matter. It’s really a powerhouse place, so I’m excited to join. University leadership has also been very supportive of the startup, they’re strongly encouraging of the entrepreneurial direction of faculty, and that’s not the case at a lot of other places.

What is your favorite element and/or elementary particle?

My favorite element has to be aluminum. That’s the superconductor we use the most. The same aluminum that you could use to wrap a hot dog at a baseball game to keep it warm, you can instead cool it down to below one degree Kelvin and it becomes a superconductor. And it makes great Josephson junctions for qubits.

What hobbies and interests do you have?

Well, I’m still a musician, I’m a flutist. I don’t really make money on it anymore, but I was a professional musician for a while. For the last three years of grad school, I had a job in a professional orchestra. I do still play occasionally, and I’ll have to see how much time I have when we get to Madison. My wife is a professional musician. She’s an oboist and she’ll be working part time in the School of Music developing a new monthly recital series.

Welcome, Professor Ben Woods!

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Ben Woods

Condensed matter theorist Ben Woods joined the department as an assistant professor this fall. Originally from a small town in North Dakota, Woods studied physics at the University of North Dakota and earned a PhD in physics from West Virginia University. He first came to UW–Madison for a postdoc with Mark Friesen in 2021, and now moves into his faculty role.

Please give an overview of your research.

I primarily work in two main areas of condensed matter theory and quantum information science. The first area is the theory of semiconductor quantum dots, with applications towards building and operating quantum computers based on spin qubits. Quantum dots can be thought of as artificial atoms in which electrons are trapped and manipulated within a semiconductor, such as silicon, by metallic gates that sit on top of the semiconductor. An electron in the quantum dot forms the basis for a type of qubit called a spin qubit, where the quantum information is stored in the spin of the electron. I investigate how we can build higher quality spin qubits. One aspect of this is analyzing and designing single and two qubit gates such that their efficiency and noise resiliency can be improved. Another aspect is studying the materials and design of quantum dot devices to optimize certain properties, such as how the qubits respond to an external magnetic field. I am also interested in quantum dot arrays as a platform for quantum simulation. Here the idea is to engineer the interactions between the quantum dots to emulate a quantum system of interest.

The other area I work in is semiconductor-superconductor heterostructures. Here, you’re trying to combine desirable properties of both types of materials to create interesting devices that would otherwise be impossible. I study semiconductor-superconductor heterostructures that can give rise to exotic particles known as Majorana zero modes, which form the basis for topological qubits. These qubits are immune to certain error sources that more conventional types of qubits are not. I am trying to understand the effects of disorder on these heterostructures and develop new schemes in which Majorana zero modes can be realized.

What are one or two of the main projects your group will work on first?

One initial project will focus on designing a new qubit architecture for quantum dot spin qubits. In the most conventional type of spin qubit, you have a single electron spin that is manipulated by jiggling it with an electric field back and forth within a single quantum dot. It turns out, however, that these qubits can be manipulated more efficiently if you can hop electrons between multiple quantum dots. Specifically, I’ve devised new schemes involving three dots in a triangular geometry in which single-qubit gates can be performed quite efficiently. These ideas work in principle, but now it’s a matter of quantitatively studying how noise resilient the scheme is and how finely tuned the system parameters need to be for things to go as planned.

A second initial project is more towards quantum simulation using quantum dot arrays. The project will focus on studying magnetism in quantum dot arrays. In other words, asking how the spins of the quantum dot electrons organize due to their mutual interaction. One interesting wrinkle in these quantum dot arrays based on silicon is that there is a valley degree of freedom in addition to the usual spin degree of freedom. The project involves understanding the effects on the magnetic ordering due to this additional valley degree of freedom. Specifically, I am interested in how fluctuations in the valley degree of freedom from one dot to the next can impact magnetic ordering.

What attracted you to Madison and the university?

There were two main reasons. First, my wife had gotten a residency as an anesthesiologist at the UW hospital. So that was an obvious motivation. Second, one of my grad school advisors knew Mark Eriksson and Mark Friesen and thought it’d be a natural fit for me to work with them as a postdoc. Since moving here, my family has enjoyed Madison, and I really like the physics department. The people are very friendly and collaborative. I am incredibly happy to be able to stay in Madison and at the UW physics department.

What is your favorite element and/ or elementary particle?

It has to be silicon, right? It’s the material I think about every day. And the world economy is largely based on stuff made with silicon. So that’s pretty cool?

What hobbies and interests do you have?

I like to play guitar, read, watch sports, and spend time with my family and friends. I have two kids, three years and six months old, who I like to spend most of my free time on.

Britton Plourde elected Fellow of the American Physical Society

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Britton Plourde (credit: Syracuse University)

Congratulations to Prof. Britton Plourde for being elected a Fellow of the American Physical Society!

Plourde was elected “For important contributions to the physics and operation of superconducting qubits, including the development of techniques for scalable qubit control and readout, and investigations of decoherence from vortices and nonequilibrium quasiparticles.” He was nominated by the Division of Quantum Information Fellowship.

APS Fellowship is a distinct honor signifying recognition by one’s professional peers for outstanding contributions to physics. Each year, no more than one half of one percent of the Society’s membership is recognized by this honor.

See the full list of 2024 honorees at the APS Fellows archive.

Welcome, Prof. Elio König!

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Elio König

This fall, condensed matter theorist Elio König returned to Madison as an assistant professor of physics. König began his education in Germany and Italy, earning a PhD from the Karlsruhe Institute of Technology in 2014. He joined UW–Madison physics as a postdoc with Alex Levchenko, then completed a second postdoc at Rutgers University. Most recently, König held a group leader position at the Max Planck Institute of Solid State Research in Stuttgart, Germany.

Please give an overview of your research.

I’m a condensed matter theorist, so I study the collective behavior of quantum particles in materials. We study electronic collective behavior — behavior of electronic systems — and I study strong correlations in that regard. We do all of this with an eye on what’s happening in the quantum computation world. Our study of quantum materials can serve as a source of inspiration for building useful quantum devices in the context of quantum computers and potentially beyond.

And then reversely, the advances in quantum technology are of great use in our studying of quantum materials. We can use them as new probes, as new experimental techniques, and at the same time there is theoretical and conceptual cross-pollination. I’m inspired by these synergies.

What are one or two main projects your group will work on first?

The main directions that I’m heading in right now are 2D materials and trying to work more into concepts related to or at the interface between quantum materials and quantum information.

In the 2D world, what I’m really fascinated by is frustrated magnetism in these 2D materials, and in particular research on quantum spin liquids. Generally, the idea is to study states of matter beyond the standard concept of spontaneous symmetry breaking. We’re interested in topologically ordered states and quantum order, which is essentially based on the entanglement of many, many particles together. And these states of matter are relevant for topological quantum error correction codes. I think there’s also quite a lot of interest at UW already, both theoretically but also particularly experimentally, in 2D materials and I hope to collaborate with my future colleagues in that regard.

On the side of quantum materials and quantum information theory, there are ongoing projects that I want to extend on. I want to look for new setups for very robust quantum computers and topological quantum computation. At the same time, I want to use devices which are available right now for emulation of quantum many body systems.

What attracted you to Madison and the university?

This question is related to the question: why am I coming back to the States? I very much enjoyed my five years in the States, personally but also scientifically. The main aspect that I find more present in the States than in Europe is a more visionary approach to science. And I think this is also true for UW, so this is something that attracted me to UW. I know the department maybe better than other new faculty and it’s a fantastic place to work. I know that there are very inspiring colleagues, and I hope that there will be a chance to collaborate with them. And finally, Madison is a very nice place to live. I think it’s probably the nicest city of this size that I’ve seen in the States.

What is your favorite element and or elementary particle? [editor’s note: this interview was conducted via Zoom while König was on a cycling trip through the Italian Alps]  

I read some previous interviews, so I knew this question was coming. And when I was biking today, I was thinking about it. Given that I’m mountain biking in the Alps and it’s really intense, I decided that oxygen is the element I want to go for. I can’t get enough of it right now. Oxygen is of course a symbol for the life that humans and animals have on this planet. Finally, oxygen is also a symbol for the advances of science and scientific revolutions, for example Lavoisier’s pioneering work in this regard.

What hobbies and interests do you have?

I really enjoy biking — mountain biking and gravel biking in particular. This is the third time that I’m transversing the Alps. I got very much into dancing in the last three years in Stuttgart. I still dance forró, or Brazilian couple dancing, from time to time. I also like playing sports, particularly soccer and squash.

Mark Eriksson named Steenbock Professor

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This story was originally published by the Office of the Vice Chancellor for Research

Mark Eriksson, professor of physics, and Mikhail Feldman, professor of mathematics, have been named recipients of UW–Madison Steenbock Professorships.

“This professorship is among the most prestigious and important professorships for researchers at the UW–Madison,” says Cynthia Czajkowski, interim vice chancellor for research. “This recognition is accompanied by discretionary funds to provide recipients the freedom to explore innovative research directions and to explore new approaches to their research areas.”

In the early 1980s, Evelyn Steenbock initiated a program to endow a series of professorships in the natural sciences in honor of her late husband, Harry Steenbock, emeritus professor of biochemistry.

Harry Steenbock (1886-1967) developed an inexpensive method of enriching foods with Vitamin D. His discovery led to the eradication of rickets, the bone-deforming deficiency disease, throughout most of the world. He is also renowned for his discovery of the conversion of carotenes to vitamin A.

Steenbock assigned his patents for advances in human and animal nutrition to the Wisconsin Alumni Research Foundation (WARF), and accumulated royalties from Steenbock’s patents supplied about half the funds for the Steenbock Memorial Library construction on campus. Steenbock Memorial Library is a primary resource library for the students, faculty and research staff at the UW­–Madison.

The Steenbock Professorship provides research funds to recipients annually for 10 years and honors those faculty who have made major contributions to the advancement of knowledge, primarily through their research endeavors at UW­–Madison, but also as a result of their teaching and service activities.

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Mark Eriksson

Eriksson, awarded the Steenbock Professorship in the Physical Sciences, was recently chair of the Department of Physics. He joined the UW–Madison physics faculty in 1999 and is a world-leading expert in the development of quantum information systems using solid-state quantum dot qubits.

As department chair, Eriksson promoted the Wisconsin Idea by supporting the department’s role in connecting with audiences all around the state of Wisconsin, including restarting The Wonders of Physics Traveling Show.

Eriksson received a bachelor’s degree in physics and mathematics from UW–Madison in 1992, received his PhD from Harvard University and was a postdoctoral member of technical staff at Bell Labs.

His research has focused on quantum computing, semiconductor quantum dots and nanoscience. He leads a team dedicated to developing spin qubits in gate-defined silicon quantum dots with the goal of enabling quantum computers, which manipulate information coherently, to be built using many of the materials and fabrication methods that are the foundation of modern, classical integrated circuits.

Eriksson is widely recognized for engaging collaborative partnerships with industry, government leaders and other university research institutions to tackle some of the greatest challenges in quantum information science and technology. Last year, the Eriksson group announced its partnership with Intel and HRL Laboratories as part of the LPS Qubit Collaboratory (LQC) national Quantum Information Science Research Center hosted at the Laboratory for Physical Sciences at the University of Maryland, College Park to collaborate on research in advanced computer technologies.

“I intend to use the award to explore new opportunities in silicon-based quantum computing, including new ideas for connecting qubits to each other across large distances, and the use of near-atomic-scale metamaterials to endow semiconductors with properties even better suited to quantum computing than those available today,” Eriksson says.

Justin Edwards earns National Defense Science and Engineering Graduate Fellowship

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Physics PhD and ECE MS student Justin Edwards has been awarded the prestigious National Defense Science and Engineering Graduate Fellowship in the category of Physics (including Optics), with a proposal titled “Multispectral imaging in the near infrared for next-generation analog night vision systems”. Justin is advised by ECE Professor and physics affiliate professor Mikhail Kats and collaborates extensively with ECE PhD students Rabeeya Hamid and Demeng Feng, and the group of Dan Congreve at Stanford University.

Mark Saffman part of team awarded in latest round of Research Forward funding

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This story was originally published by the OVCR

The Office of the Vice Chancellor for Research (OVCR) hosts the Research Forward initiative to stimulate and support highly innovative and groundbreaking research at the University of Wisconsin–Madison. The initiative is supported by the Wisconsin Alumni Research Foundation (WARF) and will provide funding for 1–2 years, depending on the needs and scope of the project.

Research Forward seeks to support collaborative, multidisciplinary, multi-investigator research projects that are high-risk, high-impact, and transformative. It seeks to fund research projects that have the potential to fundamentally transform a field of study as well as projects that require significant development prior to the submission of applications for external funding. Collaborative research proposals are welcome from within any of the four divisions (Arts & Humanities, Biological Sciences, Physical Sciences, Social Sciences), as are cross-divisional collaborations.

Physics professor Mark Saffman is part of a team awarded funding in Round 4 of the Research Forward competition for their project:

Quanta sensing for next generation quantum computing

Future quantum computers could open new scientific and engineering frontiers, impacting existential challenges like climate change. However, quantum information is delicate; it leaks with time and is prone to significant errors. These errors are exacerbated by imperfect reading and writing of quantum bits (qubits). These challenges fundamentally limit our ability to run quantum programs, and could hold back this powerful technology. Fast and accurate qubit readout, therefore, is essential for unlocking the quantum advantage. Current quantum computers use conventional cameras for reading qubits, which are inherently slow and noisy.

This research project will use quanta (single-photon) sensors for fast and accurate qubit readout. Quanta sensors detect individual photons scattered from qubits, thus enabling sensing qubits at 2-3 orders of magnitude higher speeds (few microseconds from ~10 milliseconds), thereby transforming the capabilities (speed, accuracy) of future quantum computers, and for the first time, paving the way for scalable and practical quantum computing.

Principal investigator: Mohit Gupta, associate professor of computer sciences

Co-PIs: Mark Saffman, professor of physics; Swamit Tannu, assistant professor of computer sciences; Andreas Velten, associate professor of biostatistics and medical informatics, electrical and computer engineering