News & Research Highlights

When it comes to creating ever more intriguing quantum systems, a constant need is finding new ways to observe them in a wide range of physical scenarios.  JILA Fellow Cindy Regal and JILA and NIST Fellow Ana Maria Rey have teamed up with Oriol Romero-Isart, a professor at the University of Innsbruck and IQOQI (Institute for Quantum Optics and Quantum Information) to show that a trapped particle in the form of an atom readily reveals its full quantum state with quite simple ingredients, opening up opportunities for studies of the quantum state of ever larger particles.

Surrounded by some of the world’s most advanced lasers, computers, and microscopes sits Brendan McBennett, a graduate student at JILA. McBennett has been working in the laboratories of JILA Fellows Margaret Murnane and Henry Kapteyn, as part of the KM group since 2019, excited to see his research advance significantly over that time. “We use ultraviolet and extreme ultraviolet (EUV) lasers to study heat flow in nanostructured materials,” McBennett states. “EUV photons have a higher photon energy that makes them insensitive to electron dynamics in most materials, combined with nanometer wavelengths. This allows them to very precisely probe surface deformations induced by heat - or thermal phonons – to capture new materials behaviors.” In simple terms, McBennett is looking at heat dissipation in nanoelectronics. “Our experiments are providing a better understanding of phonon thermal transport in nanomaterials to inform the development of new predictive theories,” he says. “The field of phonon transport is still in its infancy, compared to our understanding of electrons and spins. There is a lot of technological potential, for energy efficiency, smarter design of nanoelectronics and quantum devices, and phonon-photon and phonon-electron analogs like phononic crystals and thermal diodes.” McBennett’s previous work at NREL (National Renewable Energy Laboratory) studied the power grid under varying renewable energy and energy efficiency scenarios, and his current research zooms in on this previous focus. 

There are many methods to determine what the limits are for certain processes. Many of these methods look to reach the upper and lower bounds to identify them for making accurate measurements and calculations. In the growing field of quantum sensing, these limits have yet to be found.  That may change, thanks to research done by JILA Fellow Graeme Smith and his research team, with JILA and NIST Fellow James Thompson In a new study published in Physical Review Applied, the JILA and NIST researchers collaborated with scientists at the quantum company Quantinuum (previously Honeywell Quantum Solutions) to try and identify the upper limits of quantum sensing.

At ultra-cold temperatures, quantum mechanics dictate how particles bump into each other. The collisions depend both on the quantum statistics of the colliding partners (their location within the medium) and on their collisional energy and angular momentum.  The angular momentum of the particles creates an energy barrier, a field of energy that prevents two molecules from interacting, and which can also affect particle dynamics in the quantum realm. The two main types of interactions at the quantum level are s-waves and p-waves. S-wave types of collisions happen naturally between fermions when they exist together in two different internal states and happen with zero angular momenta, which creates a low energy barrier. That means that atoms can collide “head-on.” S-wave collisions have been very well studied and characterized.  However, quantum statistics prevents identical fermions (those having the same internal state) to collide via s-wave interactions, instead forcing them to interact via the so-called “p-wave” channel. 

However, quantum statistics prevents identical fermions (having the same internal state) to collide via s-wave interactions, instead forcing them to interact via the so-called “p-wave” channel.  In contrast with s-wave interactions, p-wave interactions are penalized by the aforementioned energy barrier.In order to collide, particles need to carry a non-zero angular momentum in order to overcome that barrier—they need to spin around each other, like a pair of dancers. The net angular momentum of the partners can give rise to rich quantum behaviors and phases of matter that have been intensively sought in real materials and cold atoms, but which have not yet been found. Besides the energy barrier, the dynamics of three-body recombination, which involves interactions when three atoms are present rather than two, can make it complicated to study p-wave interactions in an isolated space. To overcome these problems, and to measure coherent p-wave interactions between two particles for the first time, JILA and NIST Fellow Ana Maria Rey and her group, together with JILA theorist Jose D’Incao, collaborated with the University of Toronto experimentalist team led by Joseph Thywissen. They devised a method to isolate pairs of atoms in an optical lattice, a web of laser light that helps isolate and control particle interactions, then gave the particles the necessary angular momentum, or twist, for the atoms to collide via p-wave using specific laser beam frequencies. This resulted in the first observation of p-wave interactions in an experiment. The researchers have published their findings in the journal Nature.

JILA, NIST Fellow, and University of Colorado Boulder Professor Jun Ye has been appointed to the National Quantum Initiative Advisory Committee. In a recent announcement, President Biden advanced the National Quantum Initiative by appointing fifteen experts in quantum information science to the National Quantum Initiative Advisory Committee (NQIAC), with Ye being one of the members. 

JILA and NIST Fellow as well as University of Colorado Boulder Professor Dr. Jun Ye has been awarded a 2022 Gold Medal from the U.S. Department of Commerce (DOC). The gold medal is the highest honorary award given by the DOC and "is granted by the Secretary for distinguished performance characterized by extraordinary, notable, or prestigious contributions that impact the mission of the Department and/or one or more operating units," according to the DOC. 

JILA Fellow, NIST Physicist, and University of Colorado Physics professor Adam Kaufman has been awarded a grant as part of the 2023 Young Investigator Research Program, or YIP. YIP was launched by the Air Force Office of Scientific Research, or AFOSR, the basic research arm of the Air Force Research Laboratory. The AFOSR's mission is to support Air Force goals of control and maximum utilization of air, space, and cyberspace. To do this, AFSOR is awarding $25 million in grants to 58 scientists and engineers from 44 research institutions and businesses in 22 states in 2023. 

JILA graduate student Aaron Young, a researcher in JILA Fellow and NIST Physicist Adam Kaufman’s laboratory has been awarded a 2022 University of Chicago Quantum Creators Prize. The prize is part of the Chicago Quantum Exchange, one of the largest organizations celebrating quantum research and computing in the U.S. As Young explained: “This award is relatively new, this is only the second year it's been around, but I think it does a good job of providing some visibility to junior people in the field - particularly to people outside the academic community like those in industry or in government.” To promote early career research and diversity within the field of quantum science, award winners receive an honorarium of $500, a prize certificate, and reimbursed travel to the 2022 Chicago Quantum Summit. 

JILA Fellow and University of Colorado Boulder Distinguished Professor Andreas Becker has been awarded a 2023 fellowship to Optica (formerly the Optical Society of America). Becker's work at JILA focuses on the analysis and simulation of ultrafast phenomena in atoms, molecules, and clusters, in particular attosecond electron dynamics, coherent control, and molecular imaging. Using special laser frequencies, Becker and his team are able to study the dynamics of these atoms and molecules in different time scales. 

JILA Fellow Margaret Murnane has been selected as a recipient of the 2022 Institute of Physics Isaac Newton Medal and Prize. This prestigious award honors the legacy of the famous physicist Sir Isaac Newton, by commending those who have made world-leading contributions in the field of physics. Murnane received the award for pioneering and sustained contributions to the development of ultrafast lasers and coherent X-ray sources and the use of such sources to understand the quantum nature of materials.

JILA and NIST Fellow James K. Thompson’s team of researchers have for the first time successfully combined two of the “spookiest” features of quantum mechanics to make a better quantum sensor:  entanglement between atoms and delocalization of atoms.  Einstein originally referred to entanglement as creating spooky action at a distance—the strange effect of quantum mechanics in which what happens to one atom somehow influences another atom somewhere else. Entanglement is at the heart of hoped-for quantum computers, quantum simulators and quantum sensors.  A second rather spooky aspect of quantum mechanics is delocalization, the fact that a single atom can be in more than one place at the same time.  As described in their paper recently published in Nature, the Thompson group has combined the spookiness of both entanglement and delocalization to realize a matter-wave interferometer that can sense accelerations with a precision that surpasses the standard quantum limit (a limit on the accuracy of an experimental measurement at a quantum level) for the first time.  By doubling down on the spookiness, future quantum sensors will be able to provide more precise navigation, explore for needed natural resources, more precisely determine fundamental constants such as the fine structure and gravitational constants, look more precisely for dark matter, or maybe even one day detect gravitational waves.

Walk down to the basement labs of JILA and you're sure to find something interesting. From atomic clocks to biophysics, researchers are hard at work advancing scientific and technological frontiers. One of these researchers is graduate student Dhruv Kedar. Kedar works in JILA and NIST Fellow Jun Ye's lab, focusing on laser development for a range of applications including optical atomic clocks and optical timescales. “We're really just trying to make the world's best lasers as part of the atomic clock,” explained Kedar. “We do a good job of isolating out any sort of environmental effects so the atomic frequency of the clock doesn't change but gets more precise.” As optical atomic clocks use a series of lasers to control and measure the quantum state evolution inside an atom, which will redefine the SI unit of Second in the foreseeable future, improving the lasers to be themselves free of environmental noise is an important task. 

How does a scientist become interested in quantum physics? For Ana Maria Rey, both a JILA and NIST Fellow, the answer involves a rich and complicated journey. Quantum Systems Accelerator, a National QIS Research Center funded by the United States Department of Energy Office of Science, featured Rey in a new article series in honor of Hispanic Heritage Month. In this article, Rey shares her story and her current research. 

Atomic clocks are essential in building a precise time standard for the world, which is a big focus for researchers at JILA. JILA and NIST Fellow Jun Ye, in particular, has studied atomic clocks for two decades, looking into ways to increase their sensitivity and accuracy. In a new paper published in Science Advances, Ye and his team collaborated with JILA and NIST Fellow Ana Maria Rey and her team to engineer a new design of clock, which demonstrated better theoretical understanding and experimental control of atomic interactions, leading to a breakthrough in the precision achievable in state-of-the-art optical atomic clocks.

Adam Kaufman — a JILA Fellow, NIST (National Institute of Standards and Technology) Physicist, and University of Colorado Boulder Professor — has been awarded the American Physical Society's (APS) 2023 I.I. Rabi Prize in Atomic, Molecular, and Optical (AMO) physics. 

Boulder, Colo. — Physicist Adam Kaufman of both JILA and the U.S. Department of Commerce’s National Institute of Standards and Technology (NIST) has been awarded the 2023 New Horizons in Physics Prize from the Breakthrough Prize Foundation for his work in advancing the control of atoms and molecules to improve atomic clocks and quantum information processing. 

How a woman from Colombia overcame obstacles to become a leading theoretical physicist and develop the world’s most accurate atomic clock. -From the "Optica Community" article

Of all the atoms that quantum physicists study, alkaline atoms hold a special place due to their unique structure. Found in the second column of the periodic table, these atoms have two outer electrons, allowing the atoms to interact with one another in intriguing ways. “They have received a lot of attention in recent years among the physics community because of two reasons,” explained JILA and NIST Fellow Ana Maria Rey. “One is that they have a unique atomic structure, which makes them ideal for atomic clocks. This is because they have a long-lived electronic excited state that can live longer than 100 seconds. The second is that their electronic and nuclear spin degrees of freedom are highly decoupled and therefore the nuclear spins do not participate in the atomic collisions.”

Like planets orbiting the sun while rotating, an atom's electrons orbit the nucleus while spinning. The nucleus itself also spins, and this spin can be linked, or “coupled” to the electrons' spins. If the nuclear spin is coupled, it (indirectly) participates in collisions with other atoms. If it is not coupled (decoupled), the nuclear spin is uninvolved in these collisions. For decoupled nuclei, their properties give rise to a unique symmetry called SU(n) symmetry, where the strength of the interactions between the atoms is uninfluenced by what nuclear spins are involved in the collisions. “Here n corresponds to the number of nuclear spin states,” Rey added. “In an alkaline earth atom like strontium, it can be up to 10.” In a new paper published in PRX Quantum, Rey and her team of researchers proposed a new method for seeing the quantum effects enabled by SU(n) symmetry in current experimental conditions, something that has been historically challenging for physicists.

Quantum science promises a range of technological breakthroughs, such as quantum computers that can help discover new pharmaceuticals or quantum sensors for navigation. These capabilities rest on two unusual properties of quantum systems, superposition and entanglement. Just as a computer register stores information in the zeros or ones of classical bits, quantum bits, or qubits, store quantum information—but in the quantum world, superposition allows the qubit to be both a zero and a one at the same time. Furthermore, multiple qubits can be bizarrely correlated through a process called entanglement. When two qubits are entangled with each other, each qubit individually looks to be in a random state, but measuring one qubit reveals perfect information about its entangled partner. These properties of superposition and entanglement make qubits quite special, as they can work more efficiently than a classical computer’s bits.

However, a common challenge in actually using these quantum systems arises due to their limited memory time, or “coherence” time, which is often measured in milliseconds. Many researchers at JILA study and use superposition and entanglement of quantum systems, including JILA fellow Adam Kaufman. Previously, Kaufman and his research team focused on improving the coherence time of the strontium atoms’ superposition between the ground state and the “clock” state, so named because these two states form the basis for state-of-the-art atomic clocks. As reported in two new papers, researchers from this lab have extended these studies to much larger system sizes, with an atom in a superposition of hundreds of locations, and separately, demonstrating optical clock entanglement with seconds-scale coherence time.

Lasers have not only fascinated scientists for decades, but they have also become an integral part of many electronic devices. To create scientific-grade lasers, physicists try to control the temporal, spatial, phase, and polarization properties of the laser beam’s pulse to be able to manipulate it. One of these properties is called the orbital angular momentum (OAM), and its phase, or shape, swirls as the doughnut-shaped laser beam travels through space. There are two types of OAM, spatial (S-OAM) and spatial-temporal (ST-OAM). S-OAM describes the angular momentum of the laser beam that is parallel to the light source's propagation direction. In contrast, ST-OAM has angular momentum that moves in a motion perpendicular to the light source’s  propagation direction, which creates a time component to the momentum  [1, 2].  Because of these differences, ST-OAM is more difficult to study due to this time component. According to senior scientist Dr. Chen-Ting Liao: “The problem is that ST-OAM is very difficult to see or measure. And if we can't see or measure this easily, there's no way we can fully understand and optimize it, let alone use it for potential future applications.” To try to overcome this difficulty, a collaboration led by Dr. Liao and other researchers, including JILA Fellows Margaret Murnane and Henry Kapteyn, worked out a method to image and better analyze ST-OAM beams. Their work was subsequently published in ACS Photonics and featured on the cover [3].