With ORNL, UT Works Toward a Quantum Future

November 11, 2025

The University of Tennessee, Knoxville, expects to receive $2.3 million to play a key role in the nation’s quantum future, thanks to renewed funding for the Quantum Science Center (QSC) at Oak Ridge National Laboratory (ORNL).

The U.S. Department of Energy is investing $125 million in QSC over the next five years to pioneer quantum-accelerated high-performance computing (QHPC), developing open-source software for quantum-classical workflows that accelerate scientific advancements across multiple disciplines. Since its founding in 2018 as part of the National Quantum Initiative Act, the QSC has pooled the unique strengths of national laboratories, industry partners, and academia to build a combined research program in quantum science. UT is part of that collaboration and will receive $2.3 million to lead work in materials and models and to train early-career scientists.

With its commitment to innovation gateways in Advanced Materials and Manufacturing and Artificial Intelligence, the university is well-positioned for this assignment. In 2023, UT launched the Center for Advanced Materials and Manufacturing (CAMM), a premier Materials Research Science and Engineering Center funded by the National Science Foundation. Through experiment, synthesis, and modeling, CAMM is dedicated to discovering advanced materials for new quantum technologies and giving students the opportunity to learn in a world-class environment.

UT is a world leader in quantum spin systems and brings its unique expertise to the validation of quantum-classical computations, which are beyond the reach of conventional computation.

Physics Professor Alan Tennant is the CAMM Director.

“UT is a key part in this,” he said of QSC research. He explained that “machine learning to extract models from quantum magnets has been an important innovation from UT and CAMM, allowing parameters to be determined from materials with neutron scattering which are essential for validating quantum computations. QSC will continue to strengthen its collaboration with CAMM.”

He added that this new funding will also support UT students who will make materials, conduct neutron experiments, and undertake quantum computations.

Tennant said the QSC is building the country’s foundation for a new quantum age and that the university’s involvement puts UT at the center of that work.

“This is actually right in the heart of where tech starts connecting,” he said. “We are integral to the American road map.”

The QSC is headquartered at the Department of Energy’s Oak Ridge National Laboratory, which is managed by UT-Battelle for the DOE Office of Science. By uniting national laboratories, academic institutions and industry partners, the QSC endeavors to advance American innovation and global leadership by enhancing the computational robustness, algorithmic scalability and simulation accuracy of quantum computing systems. For more information, visit qscience.org.

NSF CAREER Award for Joon Sue Lee

October 14, 2025

Assistant Professor Joon Sue Lee has won a prestigious CAREER award from the National Science Foundation (NSF) to advance the creation of quantum materials for new quantum devices. He is the ninth member of the current physics faculty to win this award and one of three recent UT recipients.

Atomic-Scale Engineering

The NSF CAREER program supports early-career faculty with the potential to be academic role models in research and education. Since joining the department in 2020, Lee has won back-to-back teaching awards and built a research group that specializes in developing quantum materials, especially those with potential applications in quantum technologies.

The transistors and semiconductors that power smartphones and biosensors were built on understanding electrical properties. Future quantum technologies rely on the fascinating but atypical workings of quantum mechanics. In systems so small they’re measured in atoms, the physics tends to go off script. Particles can be in multiple states at the same time or they may be entangled. Properties don’t exist until they’re measured. Lee’s work navigates through this landscape to make new materials and devices for a modern world. With this NSF support, he’ll focus on a single-element material—tin (Sn)—because it has a dramatically different personality.

“Tin has two different structures,” he said. “Alpha phase is topological. Beta phase is superconducting. If you can control the growth of each phase, then you can control the electrical properties.”

Superconductivity allows electrical current to flow with no resistance. Topological phases, on the other hand, are defined by the global arrangement of a material’s electronic wavefunctions—its band topology. In conventional materials, the conduction and valence bands remain distinct. However, in topological materials, these bands can invert due to strong spin-orbit coupling.

“This inversion changes the material’s topological order, creating protected surface or edge states that allow electrons to travel without scattering,” Lee explained.

Such states are remarkably robust against defects and impurities, giving rise to exotic behaviors that bridge fundamental quantum physics and potential device applications. Combining superconductivity and topology gives scientists exciting opportunities for new technologies.

“Topological superconductivity, for example, is one of the most promising routes toward quantum computing,” Lee said. “That’s one of the big motivations.”

Using the Molecular Beam Epitaxy resources at UT’s Institute for Advanced Materials, Lee grows thin films, one layer of atoms at a time, on crystalline substrates. His goal is to selectively grow pure superconducting and topological phases of tin and put them together into structures with “atomically precise” interfaces.

“If we can achieve that, then we will be able to design materials where one area has one structure and the adjacent area has the second structure,” he said.

By adjusting the lattice parameters of underlying buffer layers of those areas, he can tune the tin phases and control their electrical properties.

“We want to explore the basic physics in these electrical states,” he said, “and also develop devices that could lead to future quantum applications.”

Professor and Department Head Adrian Del Maestro said that “Lee’s work harnesses the quantum behavior of materials for new technologies, including novel superconductors that can be used for sensing and energy applications. His lab is always bustling with undergraduate and graduate students, where he is training the workforce of tomorrow.” 

The work aligns well with the university’s strategic focus on advanced materials and manufacturing innovation gateway, part of a concentrated effort to make the most of UT’s expertise to tackle grand challenges. Lee, who has won teaching awards from the College of Arts and Sciences and the UT Alumni Association, also plans to share this research with undergraduates to inspire a new generation of scientists.

“I plan to use the data from our samples to explain or demonstrate superconductivity or topological properties in class,” he said. He added that he can also use semiconductors and insulators in his lab and “those can help students understand electrical properties of different materials.”

Lee’s five-year project began in August and includes $749,441 to support his work. He is the ninth member* of the current physics faculty to win an NSF CAREER award. The program has supported the department’s wide range of expertise, including research in condensed matter, elementary particles, biophysics, and nuclear theory.

*Adrian Del Maestro, Steven Johnston, Larry Lee, Jian Liu, Norman Mannella, Jaan Mannik, Lucas Platter, and Haidong Zhou have all won NSF CAREER Awards.

TRAINING THE NEXT GENERATION

Graduate Student Pradip Adhikari joined Joon Sue Lee’s research group in the fall of 2020 and is one of 11 graduate students to win a Graduate Advancement, Training, and Education (GATE) Award for the 2025-2026 academic year. These awards from the UT-Oak Ridge Innovation Institute’s Science Alliance support collaborative research between the university and Oak Ridge National Laboratory, providing outstanding graduate students with a 12-month appointment including a stipend, tuition, and benefits.

While he isn’t working directly on the NSF CAREER research, Lee explained that “in Pradip’s case, he’s using a different material system (but) it’s the same motivation; the same big idea about topological materials and superconductivity.”

Adhikari’s project is the device-scale interplay of unconventional superconductivity and magnetism. While they typically have an adversarial relationship (usually leading to the suppression of one state by the other) he is working with a combination of iron, tellurium, and selenium, or FeTeSe, which is a notable example of an unconventional superconductor with co-existing superconductivity and magnetism.

“The interplay of topology, magnetism, and superconductivity gives rise to exotic and robust quantum states, making such materials a fertile ground for discovering new physics,” Adhikari said. “My research interest lies in the synthesis of high-quality topological materials, fabricating devices from them, and studying their properties at the device scale. I am particularly excited by how the unique electronic behaviors of these materials can be explored and harnessed for next-generation quantum technologies.” 

Enhancing Thermoelectric Effects

September 29, 2025

UT’s physicists have helped develop a new approach to enhancing thermoelectric materials, energy converters that can turn waste heat into electricity or electricity into cooling and heating.

Thermoelectric materials use heat to create electricity by one of two avenues. The Seebeck effect moves current from the hot side to the cold side of a material. The temperature difference generates electricity. The lesser-studied Nernst effect creates voltage in a transverse direction but requires an external magnetic field. While this complicates its possible uses, this effect intrigues researchers because its geometry provides greater efficiency.

In this study, Dongliang Gong, Junyi Yang, Shashi Pandey, Dapeng Cui, Yang Zhang, and Jian Liu* were part of the team that synthesized an antiferromagnetic oxide material that could generate transverse voltage without the need for an external magnetic field. This anomalous Nernst effect (ANE) is the largest among the known magnetic oxides because of the magnetically broken symmetry. This opens a path to looking at other materials with similar symmetry configuration as candidates for greater thermoelectric efficiency.

Read the full research highlight from Argonne National Laboratory, or the original paper in Nature Communications.

*Dongliang Gong is a former postdoctoral research associate.

Junyi Yang completed his PhD in 2022 and is now working at Argonne National Laboratory.

Shashi Pandey graduated with a PhD in 2024 and is currently a postdoc at the University of Michigan.

Dapeng Cui is a postdoctoral research associate.

Yang Zhang is an assistant professor of physics. Jian Liu is a professor of physics.

Research Overview: The Power of RIXS

August 28, 2025

Courtesy of Bains Professor Steven Johnston and students Jinu Thomas and Debshikha Banerjee

Quantum materials—systems whose properties are dominated by quantum mechanical many-body effects—represent one of the most exciting frontiers of condensed matter physics. They also have the potential to revolutionize technology with applications in superconductors, magnets, and sensors.

In these systems, it is common for different degrees of freedom like spin, charge, orbital, and lattice vibrations to become intricately entangled, making it difficult to identify which is the driver of a given phenomenon. This entanglement makes quantum materials hard to model, but it also produces a wide range of exotic phenomena, including high-temperature superconductivity, various types of density waves, topological states, and more. Notably, the Bains Professor Steven Johnston’s research group has long been interested in how electrons couple to atomic vibrations and how this interaction can influence the properties of these materials.

Advanced experimental and numerical techniques are required to unravel the complex behavior present in quantum materials. Among them, resonant inelastic x-ray scattering (RIXS) has emerged as a powerful spectroscopic tool due to its ability to simultaneously probe spin, charge, orbital, and lattice excitations in a single experiment. A recent perspective piece published in Physical Review X by Johnston and Adjunct Professor Mark Dean, along with their colleagues, sheds light on applications of RIXS in quantum materials. More recently, members of Johnston’s group have published a study in Physical Review Letters, presenting state-of-the-art calculations for RIXS response for a correlated quantum material with strong interactions to phonon modes via a novel kinetic energy coupling mechanism.

First author and PhD student Debshikha Banerjee, together with Jinu Thomas, Alberto Nocera (University of British Columbia), and Johnston, used the density matrix renormalization group (DMRG) to predict the RIXS spectra for a one-dimensional Hubbard chain coupled with Su-Schrieffer-Heeger (SSH)-like electron-phonon coupling. This model has established itself for studying chain systems like Sr₂CuO₃, which has long served as a platform for studying quantum magnetism in low-dimensional systems.

Most studies of electron-phonon coupling have focused on simplified models (e.g., Holstein or Fröhlich), where coupling is between electron density and lattice displacements. In contrast, the SSH model captures lattice vibrations that alter atomic bond lengths, an interaction present in all materials. SSH electron-phonon interactions have gained widespread interest in recent years following predictions that SSH interactions can contribute to high-temperature superconductivity. SSH interactions have also been tied to topological edge states, a topic of interest in recent years. To test these theoretical claims, the community needs experimental protocols to identify the existence of SSH interaction in materials. Banerjee et al.’s work demonstrates how RIXS can be exploited to identify and quantify SSH interactions in quantum materials.

This study builds on a recent work led by PhD student Jinu Thomas and the same team, published in Physical Review X, which has adv­­anced the state-of-the-art modeling of lattice excitations in RIXS.

Understanding Cuprates of All Stripes

December 11, 2024

Steve Johnston doesn’t judge materials by their extended relatives. The department’s Bains Professor investigates how their physics can be different on a family-by-family basis as he studies what gives rise to superconductivity—electric current flowing with no resistance. Studies like these make crucial steps toward designing the quantum materials that will drive future technologies and economies.

In findings published in the Proceedings of the National Academy of Sciences (PNAS), Johnston and colleagues report how they used advanced computational modeling to show that not all families are alike and what those differences mean.

Single-Band Limits

Among the best-known high-temperature superconductors are cuprates—materials made from copper and oxygen. Discovered in 1986, they’ve been widely studied but still present a lot of unanswered questions. Theorists like Johnston have seen that the underlying properties—spin and charge and how those correlate—can be inconsistent across cuprate families. Sometimes the physics assists with superconductivity; sometimes it competes with it.

Johnston explained that in basic terms what happens in these materials is that copper and oxygen atoms form a plane. The standard for describing that system is the single-band Hubbard model.    

“You can think of it as removing oxygen from the plane to get this sort of effective copper-only description,” he said. “For years, people thought that really describes the physics.”

He said the model captures a lot of details that experiments have discovered about cuprates. It does a good job of showing how the electrons’ spins and charges form an alternating pattern of rows, or “stripes.” It accounts for the addition or subtraction of electrons from cuprate planes (called doping) that causes them to superconduct.

Yet there are limits to what this framework can do, especially in showing material-specific characteristics among different cuprate families.

“Everyone focused on these single-band descriptions because they’re easier to handle computationally,” Johnston said. “(If) you put the oxygen back in, it becomes a more complex problem and you need even more computational resources to solve it.”

Collaborating with partners from the University of Illinois and Oak Ridge National Laboratory (ORNL), Johnston and Research Assistant Professor Benjamin Cohen-Stead approached this complexity with the three-band Hubbard model, and used advanced algorithms and computing power to get a more detailed picture of the system.

Common Elements; Different Families

The single-band model predicts a reliable pattern for electronic charge and magnetism in cuprates. As Johnston explained, you can picture the “stripes” in cuprates as a kind of atomic board with alternating rows. One row will have lots of holes left by removing electrons while the next row will have no holes at all, and so on, in a repeating pattern. The phases of the charge in the hole-rich region and magnetism in the hole-depleted rows are locked with the neighboring regions.

“So, when the period of one changes, the period of the other changes,” he said. “That’s what’s seen experimentally in a lot of these systems and that’s what the single-band model predicts.”

The work he and fellow scientists reported in PNAS found something different.

“What we’re finding in the three-band model is that (the stripes) are no longer coupled,” Johnston explained. “The spin and charge start to split apart; they’re no longer intertwined,” so you can independently change spin and charge modulations.

“If you take the single-model Hubbard model at face value, you basically expect all cuprates to be the same,” he said. “And we know that doesn’t happen experimentally. What this is telling you is that once you put the oxygen back in, you can start accounting for some of these differences that appear between bismuth-, lanthanum-, and yttrium-based cuprates. You can sort of understand these material-dependent factors. It’s an important step in separating out what’s universal and what’s material-specific.”

Knowing how different superconducting materials behave is the key to putting them to work.

“If we understand what makes a high-temperature superconductor superconduct, we have a better chance of engineering them,” Johnston explained. “In the end, we want to design materials and control the properties of these quantum systems with a high degree of precision.”

Efficient Teamwork

What makes this research possible is writing and running computational models to help scientists define a material’s properties. Johnston has long worked with colleague Thomas Maier of ORNL’s Computational Sciences and Engineering Division, who was a co-author on the PNAS paper. Maier is also a co-principal investigator on a National Science Foundation Elements grant Johnston won earlier this year. That award will help them expand a suite of codes called SmoQy that Johnston’s group developed.

Instead of coming up with a new model whenever a new material comes out, this library has codes ready to use from the get-go. (The SmoQy suite played a starring role in the PNAS research.) Johnston and Maier will build this collection further with another time saver. They’ll model a small part of an infinite system, then embed that model with an average approximation for the remainder of the system to account for all the quantum mechanics involved.

“We’re a computing university,” Johnston said of UT. “We’re very well-known for computing, so it makes sense that we develop these software stacks and help push the field forward using these tools.”

Technological progress like this includes the hard work of building a strong foundation. Two years ago, Johnston and Professor Hanno Weitering created a monolayer superconductor that landed on the cover of Nature Physics.

“That really grew out of our microscopic understanding of the Hubbard model and the physics of cuprate-like materials,” Johnston explained. “If you go back and look at the physics of semiconductors, the same thing happened there. Semiconductors were developed by people really trying to understand quantum theories of matter. That foundation has formed the basis for our entire modern economy. And it wouldn’t have happened without that fundamental research.”

Haidong Zhou Elected APS Fellow

October 9, 2024

Haidong Zhou has a gift for navigating frustration, a skill that’s earned him election to the 2024 class of American Physical Society Fellows.

A Positive Spin on Frustrating Circumstances

Zhou, professor of physics, believes that technology’s future depends on the creation of new materials and the novel properties they offer. It’s an interest he developed as an undergraduate at the University of Science and Technology of China, where he worked with Professor Xiaoguang Li. That’s where he started studying manganites, materials that exhibit giant magnetoresistance—an effect that’s found a home in applications as varied as data storage, biosensors, and food safety. He continued those studies with his doctoral work at the University of Texas at Austin with Professor (and Nobel Laureate) John Goodenough.

It was his next stop, as a postdoc at the National High Magnetic Field Laboratory, where Zhou was introduced to geometrically frustrated magnets by his supervisor, Professor Chris Wiebe.

How can a magnet experience frustration? It has to do with electrons. Every electron has a spin. For materials whose atoms are arranged in a square lattice (kind of like a jungle gym), the electrons at each corner spin in alternating directions—up, down, up, down. That’s not the case for materials that have a lattice structure shaped like a triangle, where the electrons get frustrated because there’s always an odd spin out, so to speak.

“The idea is that in certain materials, the spins of the materials are arranged on a certain sublattice, such as three spins occupying a triangular lattice,” Zhou explained. “With such (a) lattice, the magnets tend to exhibit exotic magnetic properties related to strong spin fluctuations.”

Taking advantage of those exotic properties advances our understanding of how materials function, spurring the development of next-generation breakthroughs in fields like quantum computing.

Try, Fail, Succeed

Zhou, who joined the physics faculty in 2012, has been creating these magnets throughout his career. Atom by atom, he chooses the elements and grows the crystals that his colleagues study (at UT and elsewhere).

“We are extremely excited for Professor Zhou to receive this well-deserved honor from his peers,” said Adrian Del Maestro, professor and department head. “The groundbreaking quantum materials made in his lab are studied by researchers worldwide and could revolutionize future quantum technologies.”

In electing him a Fellow, the APS cited Zhou for his “outstanding contributions to the synthesis and understanding of frustrated magnetic materials.”

However, creating these magnets can itself be an exercise in frustration, even for an expert.

“The difficult part is the try and fail before you succeed,” Zhou said. “For each new sample, it takes time to get the right procedure to make it.”

Eventually, though, the payoff is worth it, even if the finished product is incredibly small.

“The best part of the work is to hold the crystals made in the lab, from millimeter size to centimeter size,” he said.

That dedication to research has won Zhou numerous honors. In 2014 he won a National Science Foundation Early Career Award and in 2017 UT’s College of Arts and Sciences presented him with an Award for Excellence in Research/Creative Achievement.

With this latest recognition, Zhou becomes the 11^th APS Fellow on the current physics faculty and the department’s third elected APS Fellow in the past three years.