News & Research Highlights

The strange behaviors of high-temperature superconductors—materials that conduct electricity without resistance above the boiling point of liquid nitrogen—and other systems with unusual magnetic properties have fascinated scientists for decades. While researchers have developed mathematical models for these systems, much of the underlying quantum dynamics and phases remain a mystery because of the immense computational difficulty of solving these models.

In a new study published in Science, researchers from JILA, led by JILA and NIST Fellows and University of Colorado Boulder physics professors Jun Ye and Ana Maria Rey and JILA and CU Boulder physics professor John Bohn, used ultracold molecules to realize these models with an unprecedented level of control. Their work bridges the fields of atomic, molecular, and optical (AMO) physics with condensed matter physics, opening new doors for quantum simulations and advances in quantum technologies.

“It is very exciting that experiments with polar molecules are now reaching the point where these models can be implemented in the lab,” Rey says. “While currently, we are exploring dynamics at low filling fractions where theory effort can still have some predicting capabilities, very soon experiments will reach dense regimes intractable by theory, fulfilling the dream of quantum simulation.” 

Jun Ye, a distinguished Fellow at JILA and the National Institute of Standards and Technology (NIST) and a physics professor at the University of Colorado Boulder, has been honored with the 2025 Berthold Leibinger Zukunftspreis. 

Researchers at JILA and the University of Colorado Boulder have developed an innovative platform that combines machine learning with atom interferometry to create a universal quantum sensor. This system uses programmable atom-optic "gates" to reconfigure a single device via software for various precision measurements, such as acceleration, rotation, and gravity gradients, without the need for hardware changes. By integrating machine learning, the team optimized the design of these gates, achieving high-fidelity quantum state transformations with over 90% accuracy. This versatile platform allows for adaptive, intelligent quantum metrology, capable of switching functions through software updates. The research, part of NASA's Quantum Pathways Institute, aims to develop deployable quantum sensors for space missions, marking a significant advancement in quantum sensing and potentially bringing quantum technologies into everyday applications.

Researchers at JILA, led by Ana Maria Rey, developed a new protocol for teleporting quantum information in collective spin states of ions within a two-dimensional crystal. This involves entangling ion groups through phonon modes and using measurements to transfer quantum states. The protocol, successfully simulated with up to 300 ions, shows potential for quantum networks and distributed quantum sensing.

Understanding how molecules interact with ions is a cornerstone of chemistry, with applications from pollution detection and cleanup to drug delivery. In a series of new studies led by JILA Fellow and University of Colorado Boulder chemistry professor Mathias Weber, researchers explored how a specific ion receptor called octamethyl calix[4]pyrrole (omC4P) binds to different anions, such as fluoride or nitrate. These findings, published in The Journal of the American Chemical Society, The Journal of Physical Chemistry Letters, and The Journal of Physical Chemistry B, provide fundamental insights about molecular binding that could help advance fields such as environmental science and synthetic chemistry. 

“The main issue with understanding these interactions is that there is a competition between an ion binding to a certain receptor and that same ion wanting to be surrounded by solvent molecules,” Weber explains. “This competition impacts how effective and specific an ion receptor can be, and we currently don’t understand it sufficiently well to design better ion receptors for applications. This has been a problem for decades, and we can now try to solve it by taking a different perspective.”
 

Dr. Olivia Krohn, a former JILA graduate student and now a postdoctoral researcher at Sandia National Laboratories, has been awarded the prestigious Justin Jankunas dissertation award, given out by the American Physical Society (APS) division of chemical physics at the APS Global Summit conference. This award recognizes exceptional doctoral research that advances the frontiers of physics. Krohn’s award highlights her dissertation research, which bridges the legacy of JILA’s origins in astrophysics with its current role as a global leader in atomic, molecular, and optical (AMO) physics.

For decades, atomic clocks have been the pinnacle of precision timekeeping, enabling GPS navigation, cutting-edge physics research, and tests of fundamental theories. But researchers at JILA, led by JILA and NIST Fellow and University of Colorado Boulder physics professor Jun Ye, in collaboration with the Technical University of Vienna, are pushing beyond atomic transitions to something potentially even more stable: a nuclear clock. This clock could revolutionize timekeeping by using a uniquely low-energy transition within the nucleus of a thorium-229 atom. This transition is less sensitive to environmental disturbances than modern atomic clocks and has been proposed for tests of fundamental physics beyond the Standard Model.

This idea isn’t new in Ye’s laboratory. In fact, work in the lab on nuclear clocks began with a landmark experiment, the results of which were published as the cover article of Nature last year, where the team made the first frequency-based, quantum-state-resolved measurement of the thorium-229 nuclear transition in a thorium-doped host crystal. This achievement confirmed that thorium’s nuclear transition could be measured with enough precision to be used as a timekeeping reference. 

However, to build a precise clock, researchers must fully characterize how the transition responds to external conditions, including temperature. That’s where this new investigation—an “Editor’s Choice” paper published in Physical Review Letters—comes in, as the team studied the energy shifts in the thorium nuclei as the crystal containing the atoms was heated to different temperatures. 

​A team of physicists at the University of Colorado Boulder and the National Institute of Standards and Technology (NIST) has developed a groundbreaking laser-based device capable of analyzing gas samples to identify a vast array of molecules at extremely low concentrations, down to parts per trillion. Their findings were recently published in Nature. 

For over a century, physicists have grappled with one of the most profound questions in science: How do the rules of quantum mechanics, which govern the smallest particles, fit with the laws of general relativity, which describe the universe on the largest scales? 

The optical lattice clock, one of the most precise timekeeping devices, is becoming a powerful tool used to tackle this great challenge. Within an optical lattice clock, atoms are trapped in a “lattice” potential formed by laser beams and are manipulated with precise control of quantum coherence and interactions governed by quantum mechanics. Simultaneously, according to Einstein’s laws of general relativity, time moves slower in stronger gravitational fields. This effect, known as gravitational redshift, leads to a tiny shift of atoms’ internal energy levels depending on their position in gravitational fields, causing their “ticking”—the oscillations that define time in optical lattice clocks—to change. 

By measuring the tiny shifts of oscillation frequency in these ultra precise clocks, researchers are able to explore the influences of Einstein’s theory of relativity on quantum systems. While relativistic effects are well-understood for individual atoms, their role in many-body quantum systems, where atoms can interact and become entangled, remains largely unexplored.

Making a step forward in this direction, researchers led by JILA and NIST Fellows and University of Colorado Boulder physics professors Jun Ye and Ana Maria Rey—in collaboration with scientists at the Leibnitz University in Hanover, the Austrian Academy of Sciences, and the University of Innsbruck—proposed practical protocols to explore the effects of relativity, such as the gravitational redshift, on quantum entanglement and interactions in an optical atomic clock. Their work revealed that the interplay between gravitational effects and quantum interactions can lead to unexpected phenomena, such as atomic synchronization and quantum entanglement among particles. The results of this study were published in Physical Review Letters.

When atoms collide, their exact structure—for example, the number of electrons they have or even the quantum spin of their nuclei—has a lot to say about how they bounce off each other. This is especially true for atoms cooled to near-zero Kelvin, where quantum mechanical effects give rise to unexpected phenomena.  Collisions of these cold atoms can sometimes be caused by incoming laser light, resulting in the colliding atom-pair forming a short-lived molecular state before disassociating and releasing an enormous amount of energy. These so-called light-assisted collisions, which can happen very quickly, impact a broad range of quantum science applications, yet many details of the underlying mechanisms are not well understood. 

In a new study published in Physical Review Letters, JILA Fellow and University of Colorado Boulder physics professor Cindy Regal, along with former JILA Associate Fellow Jose D’Incao (currently an assistant professor of physics at the University of Massachusetts, Boston) and their teams developed new experimental and theoretical techniques for studying the rates at which light-assisted collisions occur in the presence of small atomic energy splittings.  Their results rely upon optical tweezers—focused lasers capable of trapping individual atoms—that the team used to isolate and study the products of individual pairs of atoms.

Researchers at the University of Colorado Boulder have developed a novel method to measure magnetic field orientations using atoms as minuscule compasses. The research, a collaboration between JILA Fellow and CU Boulder physics professor Cindy Regal and Svenja Knappe, a research professor in the Paul M. Rady Department of Mechanical Engineering, was recently published as the cover article in the journal Optica.

Congratulations to JILA graduate students Anya Grafov and Iona Binnie—who conduct their cutting-edge research in the laboratory of JILA Fellows and the University of Colorado Boulder professors Margaret Murnane and Henry Kapteyn—for their outstanding achievements at the MMM Intermag 2025 conference!

Interactions between atoms and light rule the behavior of our physical world, but, at the same time, can be extremely complex. Understanding and harnessing them is one of the major challenges for the development of quantum technologies.

To understand light-mediated interactions between atoms, it is common to isolate only two atomic levels, a ground level and an excited level, and view the atoms as tiny antennas with two poles that talk to each other.  So, when an atom in a crystal lattice array is prepared in the excited state, it relaxes back to the ground state after some time by emitting a photon. The emitted photon does not necessarily escape out of the array, but instead, it can get absorbed by another ground-state atom, which then gets excited. Such an exchange of excitations also referred to as dipole-dipole interaction, is key for making atoms interact, even when they cannot bump into each other. 

“While the underlying idea is very simple, as many photons are exchanged between many atoms, the state of the system can become correlated, or highly entangled, quickly,” explains JILA and NIST Fellow and University of Colorado Boulder physics professor Ana Maria Rey. “I cannot think of a single atom as an independent object. Instead, I need to keep track of how its state depends on the state of many other atoms in the array. This is intractable with current computational methods. In the absence of an external drive, the generated entanglement  typically disappears since all atoms relax to the ground state.” 

Atoms can, however, have more than two atomic levels. Interactions in the system can change drastically if more than two internal levels are allowed to participate in the dynamics.  In a two-level system (weak excitation) with only one photon and, at most, one excited atom in the array, one just needs to track the single excited atom. While this is numerically tractable, it is not so helpful for quantum technologies since the atoms could be thought of more as classical antennas.  

In contrast, by allowing just one additional ground level per atom, even with a single excitation, the number of configurations accessible to the system grows exponentially, drastically increasing the complexity.  Understanding atom-light interaction in multi-level settings is an extremely difficult problem, and up to now it has eluded both theorists and experimentalists.  

Rey explains, “However, it can be extremely useful, not only because it can generate highly entangled states which can be preserved in the absence of a drive since atoms in the ground levels do not decay.’’ 

Now, in a recent study published in Physical Review Letters, Rey and JILA and NIST Fellow James K. Thompson, along with graduate student Sanaa Agarwal and researcher Asier Piñeiro Orioli from the University of Strasbourg, studied atom-light interactions in the case of effective four-level atoms, two ground (or metastable) and two excited levels arranged in specific one-dimensional and two-dimensional crystal lattices. 

JILA Fellow, National Institute of Standards and Technology (NIST) Physicist and University of Colorado Boulder physics professor Dr. Adam Kaufman has been awarded the prestigious Presidential Early Career Award for Scientists and Engineers (PECASE).  President Joe Biden announced that this accolade represents the highest honor conferred by the U.S. government to early-career scientists and engineers who exhibit extraordinary potential and leadership in their respective fields. Kaufman’s groundbreaking contributions to quantum science have cemented his place among nearly 400 recipients recognized for their innovative research and commitment to advancing scientific frontiers.

Shuo Sun, Associate Fellow at JILA and Assistant Professor in the Department of Physics at the University of Colorado Boulder has been awarded a prestigious NSF CAREER Award for his research proposal, “Developing a High-Dimensional Photonic Quantum Register for the Quantum Internet.”

In the quest for ultra-precise timekeeping, scientists have turned to nuclear clocks. Unlike optical atomic clocks—which rely on electronic transitions—nuclear clocks utilize the energy transitions in the atom’s nucleus, which are less affected by outside forces, meaning this type of clock could potentially keep time more accurately than any previously existing technology. 

However, building such a clock has posed major challenges—thorium-229, one of the isotopes used in nuclear clocks, is rare, radioactive, and extremely costly to acquire in the substantial quantities required for this purpose.

Reported recently in a new study published in Nature, a team of researchers, led by JILA and NIST Fellow and University of Colorado Boulder Physics professor Jun Ye, in collaboration with Professor Eric Hudson’s team at UCLA’s Department of Physics and Astronomy, have found a way to make nuclear clocks a thousand times less radioactive and more cost-effective, thanks to a method creating thin films of thorium tetrafluoride (ThF₄). 

Isolated atoms in free space radiate energy at their own individual pace. However, atoms in an optical cavity interact with the photons bouncing back and forth from the cavity mirrors, and by doing so, they coordinate their photon emission and radiate collectively, all in sync. This enhanced light emission before all the atoms reach the ground state is known as superradiance. Interestingly, if an external laser is used to excite the atoms inside the cavity moderately, the absorption of light by the atoms and the collective emission can balance each other, letting the atoms relax to a steady state with finite excitations.

However, above a certain laser energy level, the nature of the steady state drastically changes since atoms inside the cavity cannot collectively emit light fast enough to balance the incoming light. As a result, the atoms keep emitting and absorbing photons without reaching a stable, steady state. While this change in steady-state behaviors was theoretically predicted decades ago, it hasn’t yet been observed experimentally.  

Recent research at the Laboratoire Charles Fabry and the Institut d’Optique in Paris studied a collection of atoms in free space forming an elongated, pencil-shaped cloud and reported the potential observation of this desired phase transition. Yet, the results of this study puzzled other experimentalists since atoms in free space don’t easily synchronize. 

To better understand these findings, JILA and NIST Fellow Ana Maria Rey and her theory team collaborated with an international team of experimentalists. The theorists found that atoms in free space can only partially synchronize their emission, suggesting that the free-space experiment did not observe the superradiant phase transition. These results are published in PRX Quantum. 

Physics lab courses are vital to science education, providing hands-on experience and technical skills that lectures can’t offer. Yet, it’s challenging for those in Physics Education Research (PER) to compare course to course, especially since these courses vary wildly worldwide. 

To better understand these differences, JILA Fellow and University of Colorado Boulder physics professor Heather Lewandowski and a group of international collaborators are working towards creating a global taxonomy, a classification system that could create a more equitable way to compare these courses. Their findings were recently published in Physical Review Physics Education Research.

JILA and NIST Fellow and CU Boulder Physics Professor Jun Ye has been named a 2024 Highly Cited Researcher by Clarivate. This distinction is awarded to scientists whose work ranks in the top 1% of citations globally. Ye, known for his groundbreaking contributions to precision measurement and atomic, molecular, and optical physics, joins an elite list of researchers shaping the forefront of scientific innovation.

Flari Tech Inc., a startup rooted in cutting-edge JILA research, has clinched one of the prestigious 2024 Lab Venture Challenge (LVC) grants from the University of Colorado Boulder, advancing its pioneering work to build a breathalyzer for diagnostics use targeting life-threatening diseases such as lung cancer.  

Developed at JILA by a team led by JILA and NIST Fellow and CU Boulder Physics professor Jun Ye and JILA graduate students Qizhong Liang and Apoorva Bisht, Flari Tech’s innovative diagnostic tool is powered by the Nobel Prize-winning optical frequency comb and aims to bring a novel, non-invasive, faster method for lung cancer detection for clinical use.