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

a metalilc chamber with a blue glowing orb of illuminated 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.

Atomic clocks are so precise because they take advantage of the natural vibration frequencies of atoms, which are identical for all atoms of a particular element. These clocks operate at or near the standard quantum limit, a fundamental limit on performance imposed on clocks where the atoms are all independent of each other. The only way to push the clocks past that limit is to achieve entangled states, strange quantum states where the atoms are no longer independent and they become intertwined.

a cartoon showing the atoms in their pancakes as described in the text“That turns out to be hard for a number of reasons. Entanglement requires these atoms to interact with each other, but a good clock requires them not to interact with each other or anything else,” Kolkowitz says. “So, you need to engineer a situation where you can make the atoms interact strongly, but you can also switch those interactions off. And those are some of the same requirements that are necessary for quantum computing.”

Kolkowitz is already building an optical atomic clock in his lab, albeit one that is not yet using entangled states. To make the clock, they first laser-cool strontium atoms to one millionth of one degree Celsius above absolute zero, then load the atoms into an optical lattice. In the lattice, the atoms are separated into what is effectively a tiny stack of pancakes — each atom can move around within their own flat disk, but they cannot jump into another pancake.

Though the atoms’ are stuck in their own pancake, they can interact with each other if their electrons are highly excited. This type of atom, known as Rydberg atoms, becomes close to one million times larger than an unexcited counterpart because the excited electron can be microns away from the nucleus.

“It’s kind of crazy that a single atom can be that big, and when you make them that much bigger, they interact much more strongly with each other than they do in their ground states,” Kolkowitz says. “Basically it means you can go from the atoms not interacting at all to interacting very strongly. That’s exactly what you want for quantum computing, and it’s what you want for this atomic clock.”

With the two ARO grants, Kolkowitz expects to generate Rydberg atoms in his lab’s atomic clock. One of the grants, a Defense University Research Instrumentation Program (DURIP), will fund the specialized UV laser that generates the high energy photons needed to excite the atoms into the highly excited Rydberg states. The second grant will fund personnel and other supplies. Kolkowitz will collaborate with UW–Madison physics professor Mark Saffman, who, along with physics professor Thad Walker, pioneered the use of Rydberg atoms for quantum computing.

In addition to being useful for developing new approaches to ask questions about fundamental physics in his research lab, these ultraprecise atomic clocks are of interest to the Department of Defense for atomic clock-based technologies such as GPS, and because they can be used to precisely map Earth’s gravity.

Researchers awarded Department of Energy 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.

High Energy Physics group awarded three grants totaling over $14 million

a woman in a helmet wearing a disposable facemask stands in front of lots of metal hardware and wires
a woman in a helmet wearing a disposable facemask stands in front of lots of metal hardware and wires
HEP post-doc Dr. Camilla Galloni next to the CMS end cap supporting the GEM detectors that were installed this fall. The primary structure in this photo was engineered at the UW–Madison Physical Sciences Lab. The big CSC chambers were installed, upgraded and reinstalled and operated by UW physicists. The smaller GEM chambers, which are barely visible in the interstices, are being commissioned by UW–Madison physicists through the second grant mentioned in this post.

The High Energy Physics (HEP) group at UW–Madison, which broadly focuses on identifying and understanding the fundamental aspects of particles and forces in Nature, has been awarded three significant grants in 2020. The grants — two from the Department of Energy (DOE) and one from the National Science Foundation (NSF) — are awarded either directly to UW–Madison or indirectly through multi-institution international collaborations, bringing over $14 million to the department.

The first grant, $7.37 million from DOE, funds research that is expected to help physicists understand how our Universe works at its most fundamental level. At UW­–Madison, this research includes experimental and theoretical studies into topics such as using the Higgs boson as a tool for new discoveries and identifying principles of dark matter.

The grant will fund five areas of research: 1) studies of high energy proton-proton collisions; 2) studies of neutrino interactions; 3) studies of super-weak signals from galactic dark matter particles; 4) wide-area imaging surveys using powerful new telescopes; and 5) computational and mathematical methods of quantum field theory and string theory.

Sridhara Dasu is principal investigator on this DOE grant. Co-investigators include Yang Bai, Vernon Barger, Keith Bechtol, Kevin Black, Tulika Bose, Lisa Everett, Matthew Herndon, Kimberly Palladino, Brian Rebel, Gary Shiu, Jennifer Thomas (WIPAC), and Sau Lan Wu. The grant was awarded in June 2020 and provides funding through March 2023.

The other two grants awarded will provide funding for upgrades to the Compact Muon Solenoid (CMS) project at the Large Hadron Collider (LHC) at CERN. The first is an NSF-funded grant for which Kevin Black is leading the UW–Madison effort to upgrade the CMS End Cap muon system upgrade. The $900,000 to the department is part of a larger multi-institutional grant through Cornell University and runs through 2025.

“The GEM detectors are novel micropattern gas detectors which can handle the high background rates expected in the end-cap muon detectors. They will enhance the triggering and reconstruction of forward muons which are expected to make significant improvements and increased acceptance to search for new particles and make precision measurements of known particles and interactions,” Black explains. “UW has a long history with CMS muon system with Prof Matt Herndon, Senior Emeritus Scientist Dick Loveless, and Senior Scientist Armando Lanaro leading to the design, construction, operation, and upgrade of the other end-cap subdetector system instrumented with Cathode Strip Chambers.”

The other CMS-specific grant is a four-year, $5.3 million DOE grant through Fermilab that will fund the CMS trigger upgrade. This funding will allow the UW–Madison CMS group to perform all aspects of the work involved in design, prototyping, qualification, production and validation of the calorimeter trigger system for the upgrade. When completed, the project is expected to result in the collection of 25 times more data than is currently possible. Sridhara Dasu is the principal investigator of this grant.

Q-NEXT collaboration awarded National Quantum Initiative funding

the tip of a scanning electron microscope is poised over a setup with metal clips pointing out

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.”

profile photo of Mark Eriksson
Mark Eriksson

Q-NEXT will focus on three core quantum technologies:

  • Communication for the transmission of quantum information across long distances using quantum repeaters, enabling the establishment of “unhackable” networks for information transfer
  • Sensors that achieve unprecedented sensitivities with transformational applications in physics, materials, and life sciences
  • Processing and utilizing “test beds” both for quantum simulators and future full-stack universal quantum computers with applications in quantum simulations, cryptanalysis, and logistics optimization.

Eriksson is leading the Materials and Integration thrust, one of six Q-NEXT focus areas that features researchers from across the collaboration. This thrust aims to: develop high-coherence materials, including for silicon and superconducting qubits, which is an essential component of preserving entanglement; develop a silicon-based optical quantum memory, which is important in developing a quantum repeater; and improve color-center quantum bits, which are used in both communication and sensing.

“One of the key goals in Materials and Integration is to not just improve the materials but also to improve how you integrate those materials together so that in the end, quantum devices maintain coherence and preserve entanglement,” Eriksson says. “The integration part of the name is really important. You may have a material that on its own is really good at preserving coherence, yet you only make something useful when you integrate materials together.”

Six other UW­–Madison and Wisconsin Quantum Institute faculty members are Q-NEXT investigators: physics professors Victor Brar, Shimon Kolkowitz, Robert McDermott, and Mark Saffman, electrical and computer engineering professor Mikhail Kats, and chemistry professor Randall Goldsmith. UW–Madison researchers are involved in five of the six research thrusts.

“I’m excited about Q-NEXT because of the connections and collaborations it provides to national labs, other universities, and industry partners,” Eriksson says. “When you’re talking about research, it’s those connections that often lead to the breakthroughs.

The potential impacts of Q-NEXT research include the creation of a first-ever National Quantum Devices Database that will promote the development and fabrication of next generation quantum devices as well as the development of the components and systems that enable quantum communications across distances ranging from microns to kilometers.

“This funding helps ensure that the Q-NEXT collaboration will lead the way in future developments in quantum science and engineering,” says Steve Ackerman, UW–Madison vice chancellor for research and graduate education. “Q-NEXT is the epitome of the Wisconsin Idea as we work together to transfer new quantum technologies to the marketplace and support U.S. economic competitiveness in this growing field.”

infographic of all q-next partner national labs, universities, and industry
The Q-NEXT partners

NSF Physics Frontier Center for neutron star modeling to include UW–Madison

A green, egg-shaped density in the middle has two cones of dark blue representing the gravitational waves projecting perpendicularly out either side of the green density

A group of universities, including the University of Wisconsin–Madison, has been named the newest Physics Frontier Center, the National Science Foundation announced Aug. 17. The center expands the reach and depth of existing capabilities in modeling some of the most violent events known in the universe: the mergers of neutron stars and their explosive aftermath.

The Network for Neutrinos, Nuclear Astrophysics, and Symmetries (N3AS) is already an established hub of eight institutions, including UW–Madison, that uses the most extreme environments found in astrophysics — the Big Bang, supernovae, and neutron star and black hole mergers — as laboratories for testing fundamental physics under conditions beyond the reach of Earth-based labs. The upgrade to a Physics Frontier Center adds five institutions, provides $10.9 million in funding for postdoctoral fellowships and allows members to cover an expanded scope of research.

“For 20 years, we’ve expected that the growing precision of astrophysical and cosmological measurements would make this field an increasingly important part of fundamental physics. Indeed, four monumental discoveries — neutrino masses, dark matter, the accelerating universe, and gravitational waves — have confirmed this prediction,” says A. Baha Balantekin, a professor of physics at UW–Madison and one of the principal investigators for N3AS.

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UW–Madison named member of new $25 million Midwest quantum science institute

cartoon showing a quantum hardware network

As joint members of a Midwest quantum science collaboration, the University of Wisconsin–Madison, the University of Illinois at Urbana–Champaign and the University of Chicago have been named partners in a National Science Foundation Quantum Leap Challenge Institute, NSF announced Tuesday.

The five-year, $25 million NSF Quantum Leap Challenge Institute for Hybrid Quantum Architectures and Networks (HQAN) was one of three in this first round of NSF Quantum Leap funding and helps establish the region as a major hub of quantum science. HQAN’s principal investigator, Brian DeMarco, is a professor of physics at UIUC. UW–Madison professor of physics Mark Saffman and University of Chicago engineering professor Hannes Bernien are co-principal investigators.

“HQAN is very much a regional institute that will allow us to accelerate in directions in which we’ve already been headed and to start new collaborative projects between departments at UW–Madison as well as between us, the University of Illinois, and the University of Chicago.” says Saffman, who is also director of the Wisconsin Quantum Institute. “These flagship institutes are being established as part of the National Quantum Initiative Act that was funded by Congress, and it is a recognition of the strength of quantum information research at UW–Madison that we are among the first.”

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cartoon showing a quantum hardware network
In a hybrid quantum network, hardware for storing and processing quantum information is linked together. This design could be beneficial for applications that rely on distributed quantum computing resources. | Credit: E. Edwards, IQUIST

Profs Eriksson, McDermott, Vandenbroucke awarded UW2020s

image of research station at south pole plus a purely decorative image on the bottom half

Twelve projects have been chosen for Round 6 of the UW2020: WARF Discovery Initiative, including three from faculty in the Department of Physics (Mark Eriksson, Robert McDermott, and Justin Vandenbroucke). These projects were among 92 proposals submitted from across campus. The initiative is funded by the Office of the Vice Chancellor for Research and Graduate Education and the Wisconsin Alumni Research Foundation.

The projects were reviewed by faculty across the university. The UW2020 Council, a group of 17 faculty from all divisions of the university, evaluated the merits of each project based on the reviews and their potential for making significant contributions to their field of study.

The goal of UW2020 is to stimulate and support cutting-edge, highly innovative and groundbreaking research at UW–Madison and to support acquisition of shared instruments or equipment that will foster significant advances in research.

Acquisition of a cryogen-free Physical Properties Measurement System (PPMS) for characterization of quantum materials and devices

The project addresses a barrier for UW–Madison researchers in measuring electronic, magnetic, and thermal properties of quantum materials at low temperatures, namely the increasing high costs of cryogens (liquid helium) and lack of a convenient means to perform these measurements in a shared facility. Low-temperature electronic, magnetic, and thermal properties of materials are crucial for fundamental materials discovery and for applications in quantum information, nonvolatile memory, and energy conversion devices.

This project will acquire a cryogen-free Physical Properties Measurement System (PPMS) and house it as a shared-user facility instrument within the Wisconsin Centers for Nanotechnology (CNT). This instrument would be open for all UW–Madison users.

Currently, these measurements depend on external collaborations or low-temperature setups in PI labs which either consume large amounts of cryogens or require time-consuming reconfigurations from experiment to experiment. Having a cryogen-free PPMS would allow researchers to spend less time and money in setting up experiments, potentially freeing up resources for scientific investigations that include new superconducting and topological material discoveries and characterizations of materials for advanced microelectronics and magnetic memory systems.

Jason Kawasaki, assistant professor of materials science and engineering

Jerry Hunter, director of the Wisconsin Centers for Nanotechnology

Paul Voyles, professor of materials science and engineering and MRSEC Director

Song Jin, professor of chemistry

Mark Eriksson, professor of physics

Thomas Kuech, professor of chemical and biological engineering

Daniel Rhodes, assistant professor of materials science and engineering

Chang-Beom Eom, professor of materials science and engineering

Paul Evans, professor of materials science and engineering

Michael Arnold, professor of materials science and engineering

Dakotah Thompson, assistant professor of mechanical engineering

Cracking the structure of ice: establishing a cryogenic electron backscatter diffraction and Raman capability at UW–Madison

The structure and physical properties of ice determine the behavior of glaciers, ice sheets, and polar ice caps (both terrestrial and extraterrestrial). Moreover, ice is of interest because of its unique light transmission properties, which are currently being harnessed by one of the world’s largest astrophysical experiments through the UW–led IceCube collaboration.

This project will develop the capability to perform scanning electron microscopy (SEM) of water and CO2 ice in the UW–Madison Geoscience Department, focusing on electron backscatter diffraction (EBSD) analysis for ice microstructure and Raman spectroscopy for ice composition. EBSD of ice is an extremely rare analytical capability worldwide.

Having this highly specialized type of analysis capability for ice will enable advances in glaciology, climate science, physics, materials science and planetary science. This technology can accelerate research on glacial sliding and ice deformation, and inform long-standing questions about the transformation of air bubbles to clathrates in glacial ice and their potential as archives of Earth’s past atmosphere. In addition, understanding the structure of ice is critical, for example, to accurate measurement of cosmic ray interactions in the IceCube Neutrino Observatory.

As the only lab in the U.S. offering combined ice EBSD analysis and ice Raman analysis, UW–Madison will establish itself as a nexus for cryosphere research, attracting many collaborations from outside UW–Madison.

Chloe Bonamici, assistant professor of geoscience

Lucas Zoet, assistant professor of geoscience

Shaun Marcott, associate professor of geoscience

Justin Vandenbroucke, associate professor of physics/WIPAC

John Fournelle, senior scientist of geoscience

Pavana Prabhakar, assistant professor of civil and environmental engineering

Richard Hartel, professor of food engineering

Hiroki Sone, assistant professor of geological engineering

Interdisciplinary engineering of quantum information systems

This project represents a synergistic effort toward engineering practical quantum information systems (QIS). The research unites the experimental superconducting and semiconducting qubit teams on campus with advanced materials characterization and microwave engineering expertise to uncover the underlying sources of decoherence that limit qubit performance and develop next-generation quantum devices for scalable quantum computing and quantum sensing. This effort will build new interdisciplinary connections that nourish the quantum ecosystem at UW–Madison, cutting across departmental and disciplinary lines.

The potential of QIS has been recognized recently by the $1.4 billion federal National Quantum Initiative, and the newly formed Wisconsin Quantum Institute at UW is home to world-leading efforts in the physics of QIS. This project is a next step in expanding these directions to incorporate the engineering effort necessary to develop practical systems capable of solving real-world problems.

Robert McDermott, professor of physics

Mark Eriksson, professor of physics

Susan Hagness, professor of electrical and computer engineering

Paul Voyles, professor of materials science and engineering

Kangwook Lee, professor of electrical and computer engineering