Research Highlights

The second quantum revolution is underway, a period marked by significant advances in quantum technology, and huge discoveries within quantum science. From tech giants like Google and IBM, who build their own quantum computers, to quantum network startups like Aliro Quantum, companies are eager to profit from this revolution. However, doing so takes a new type of workforce, one trained in quantum physics and quantum technology. The skillset required for this occupation is unique, and few universities expose students to real-world quantum technology. 

In 2019, a team of researchers used an international network of radio telescopes—called the Event Horizon Telescope—to take the first photo of a supermassive black hole in the center of the elliptical galaxy Messier 87 (M87). On that team of researchers was JILA Fellow Jason Dexter. Since then, Dexter has been studying M87's black hole further using simulations, with code written by researchers at the University of Illinois. As described in a new paper published in the Monthly Notices of the Royal Astronomical Society (MNRAS), Dexter, and his team of graduate students and postdoctoral researchers, collaborated with researchers at the Los Alamos National Laboratory and the University of Illinois to create a new simulation studying the edge of a black hole. 

One of the major strengths of JILA are the frequent and ongoing collaborations between experimentalists and theorists, which have led to incredible discoveries in physics. One of these partnerships is between JILA Fellow John Bohn and JILA and NIST Fellow Jun Ye. Bohn's team of theorists has partnered with Ye's experimentalist laboratory for nearly twenty years, from the very beginning of Ye’s cold molecule research when he became a JILA Fellow. Recently in their collaborations, the researchers have been studying a three-dimensional molecular gas made of ⁴⁰K⁸⁷Rb molecules. In a paper published in Nature Physics, the combined team illustrated new quantum mechanical tricks in making this gas unreactive, thus enjoying a long life (for a gas), while at the same time letting the molecules in the gas interact and socialize (thermalize) with each other.

There are many ways to diagnose health conditions. One of the most common methods is blood testing. This sort of test can look for hundreds of different kinds of molecules in the body to determine if an individual has any diseases or underlying conditions. Not everyone is a fan of needles, however, which makes blood tests a big deal for some people. Another method of diagnosis is breath analysis. In this process, an individual's breath is measured for different molecules as indicators of certain health conditions. Breath analysis has been fast progressing in recent years and is continuing to gain more and more research interest. It is, however, experimentally challenging due to the extremely low concentrations of molecules present in each breath, limited number of detectable molecular species, and the long data-analysis time required. Now, a JILA-based collaboration between the labs of NIST Fellows Jun Ye and David Nesbitt has resulted in a more robust and precise breath-testing apparatus. In combining a special type of laser with a mirrored cavity, the team of researchers was able to precisely measure four molecules in human breath at unprecedented sensitivity levels, with the promise of measuring many more types of molecules. The team published their findings in the Proceedings of the National Academy of Sciences (PNAS).

Understanding the chemical and physical properties of surfaces at the molecular level has become increasingly relevant in the fields of medicine, semiconductors, rechargeable batteries, etc. For example, when developing new medications, determining the chemical properties of a pill's coating can help to better control how the pill is digested or dissolved. In semiconductors, precise atomic level control of interfaces determines performance of computer chips. And in batteries, capacity and lifetime is often limited by electrode surface degradation.  These are just three examples of the many applications in which the understanding of surface coatings and molecular interactions are important.
The imaging of molecular surfaces has long been a complicated process within the field of physics. The images are often fuzzy, with limited spatial resolution, and researchers may not be able to distinguish different types of molecules, let alone how the molecules interact with each other. But it is precisely this–molecular interactions–which control the function and performance of molecular materials and surfaces.  
In a new paper published in Nano Letters, JILA Fellow Markus Raschke and graduate student Thomas Gray describe how they developed a way to image and visualize how surface molecules couple and interact with quantum precision. The team believes that their nanospectroscopy method could be used for molecular engineering to develop better molecular surfaces, with controlled properties for molecular electronic, photonic, or biomedical applications.

The Bose-Einstein Condensate (BEC) has been studied for decades, ever since its prediction by scientists Satyandra Nath Bose and Albert Einstein nearly 100 years ago. The BEC is a gas of atoms cooled to almost absolute zero. At low enough temperatures, quantum mechanics allows the locations of the atoms in the BEC to be uncertain to the extent that they can’t be located individually in the gas. The BEC has a special history with JILA, as it was at JILA that the first gaseous condensate was produced in 1995 by JILA Fellows Eric Cornell (NIST) and Carl Wieman (University of Colorado Boulder). Since 2005, research on dipolar BEC has continued, using different theories to describe the droplet’s interactions. In a paper recently published in Physical Review A, first author, and graduate student, Eli Halperin and JILA fellow John Bohn theorize a way to study the BEC using a hyperspherical approach. While the name may sound intimidating, the hyperspherical approach is simply a systematic way to look at a many-body problem. The many body problem refers to a large category of problems regarding microscopic systems with interacting particles. Bohn and Halperin applied this approach to a dipolar BEC specifically.

Two new papers from the Murnane and Kapteyn group are changing the way heat transport is viewed on a nanoscale, and explain the group’s surprising finding that nanoscale heat transport can be far more efficient than originally thought. One of these papers, published in the Proceedings of the National Academy of Sciences (PNAS), explains heat transport for the tiniest of hotspots, with sizes <100 nm. The other, published in American Chemical Society Nano (ACS Nano), presents a theory that is applicable to larger arrays of hotspots. Both papers postulate theories that can fully explain the surprising data collected by the team of researchers, showing that heat transport on scale lengths relevant to a wide range of nanotechnologies is more efficient than originally thought.

Atomic clocks have been heavily studied by physicists for decades. The way these clocks work is by having atoms, such as rubidium or cesium, that are "ticking" (that is, oscillating) between two quantum states. As such, atomic clocks are extremely precise, but can be fragile to shaking or other perturbations, like temperature fluctuations. Additionally, these clocks need a special laser to probe the clock. Both factors can make atomic clocks imprecise, difficult to study, and expensive to make.
A team of physicists are proposing a new type of laser that could change the future path of atomic clocks. In this team, JILA Fellow Murray Holland and Research Associate Simon Jäger theorized a new type of laser system in a paper recently published in Physical Review Letters. 

For laser science, one major goal is to achieve full control over the spatial, temporal and polarization properties of light, and to learn how to precisely manipulate these properties.  A  property of light is called the Orbital Angular Momentum (OAM), that depends on the spatial distribution of the phase (or crests) of a doughnut-shaped light beam. More recently, a new variant of OAM was discovered - called the spatial-temporal OAM (ST-OAM), with much more elusive properties, since the phase/crests of light evolve both temporally and spatially. In a collaboration led by senior scientist Dr. Chen-Ting Liao, working with graduate student Guan Gui and Nathan Brooks and JILA Fellows Margaret Murnane and Henry Kapteyn, the team explored how such beams change after propagating through nonlinear crystals that can change their color. The team published theri results in Nature Photonics. 

The basic question of how strands of nucleic acids (DNA and RNA) fold and hybridize has been studied thoroughly by biophysicists around the globe. In particular, there can be unexpected challenges in obtaining accurate kinetic data when studying the physics of how DNA and RNA fold and unfold at the single molecule level. One problem comes from temporal camera blur, as the cameras used to capture single photons emitted by these molecules do so in a finite time window that can blur the image and thereby skew the kinetics. In a paper published in the Journal of Physical Chemistry B, JILA Fellow David Nesbitt, and first author David Nicholson, propose an extremely simple yet broadly effective way to overcome this camera blur. 

Physicists at the National Institute of Standards and Technology (NIST) have linked together, or “entangled,” the mechanical motion and electronic properties of a tiny blue crystal, giving it a quantum edge in measuring electric fields with record sensitivity that may enhance understanding of the universe.

Many physicists use lasers to study quantum mechanics, atomic and molecular physics and nanophysics. While these lasers can be helpful in the research process, there are certain constraints for the researcher. According to JILA Fellow Andreas Becker: "For certain wavelengths of these laser pulses, such as deep ultraviolet, you may not know, or not be able to measure, the temporal profile." The temporal profile of a laser pulse is, however, important for researchers when analyzing data. "A lot of people cannot fully analyze their data, because they don't know the details of the pulse that was used to produce the data," said graduate student Spencer Walker. As a way to research this constraint, the Becker and Jaron-Becker laboratories collaborated to publish a paper in Optics Letters, suggesting a possible solution.

The process of creating spin-polarized electrons has been studied for some time but continues to surprise physicists. These types of electrons have their spin aligned in a specific direction. The probability of creating a spin-polarized electron from an atom tends to be rather small except in some very specific situations. Yet, in a new paper published in Physical Review A, JILA graduate student Spencer Walker, former graduate student Joel Venzke, and former undergraduate student Lucas Kolanz in the Becker Lab theorized a new way towards enhancing this probability through the use of ultrashort laser pulses and an electron’s so-called doorway states. These doorway states are excited states of an electron in an atom that is closest to its lowest energy state, the ground state. 

In a new paper published in Physical Review Letters, JILA and NIST Fellows Eric Cornell, Jun Ye, and Konrad Lehnert developed a method for measuring a potential dark matter candidate, known as an axion-like particle. Axion-like particles are a potential class of dark matter particle which could explain some aspects of galactic structure. This work is also a result of collaboration with Victor Flambaum who is a leading theorist studying possible violations of fundamental symmetries. 

When it comes to galaxies in our universe, there is still much work to do. Part of this work is being done by JILA Fellow and Assistant Professor of Astrophysics, Ann-Marie Madigan, and postdoc Dr. Angela Collier. In a  paper recently published in The Astrophysical Journal, Collier and Madigan postulate that the evolution of a galaxy can be affected by dark matter interacting with the stars within the galaxy. Galaxies evolve over billions of years, changing shape, speed of rotation, and other factors. Studying what affects galaxy evolution is important in answering questions about the foundation of our universe, of how stars and planets are formed, and the origins of dark matter.

Most researchers would agree that it is much easier to write a paper about an observed effect than a paper proving the nonexistence of the effect when it is not observed. NIST JILA Fellow Ralph Jimenez found this to be the case in contributing to a recent paper published in Physical Review Applied. The authors of this paper were originally hoping to observe the increased efficiency in two-photon absorption, a special type of process used in microscopy of living tissue, that had been reported by other research labs. This increased efficiency would be determined by an additional absorption signal than the one being produced by classical light. This additional signal came from using entangled photons. Instead, Jimenez and his team of collaborators from NIST found no additional signal in their measurements, indicating a lack of absorption entirely from the entangled photons. 

The word “quantum” can be mysterious and unfamiliar to the general public. Most of the public’s exposure to quantum technology has been Hollywoodized and framed as a “catch-all” for hard-to-define scientific processes. This misunderstanding causes problems, as quantum technology is quickly being developed and commercialized. With the  “boom” in quantum technology predicted by experts, it is important to realize the repercussions of this misunderstanding. Particularly, writers, scientists, and citizens need to be aware of how to communicate and invoke to the public, an appreciation of the true science of quantum physics. 

The idea of quantum simulation has only become more widely researched in the past few decades. Quantum simulators allow for the study of a quantum system that would be difficult to study easily and quickly in a laboratory or model with a supercomputer. A new paper published in Physical Review Letters, by a collaboration between theorists in the Rey Group and experimentalists in the Thompson laborator,y proposes a way to engineer a quantum simulator of superconductivity that can measure phenomena so far inaccessible in real materials. 

JILA Fellow Jason Dexter works with the Event Horizon Team to further study the first photograph ever taken of a black hole. 

In a significant advance toward the future redefinition of the international unit of time, the second, a research team led by the National Institute of Standards and Technology (NIST) has compared three of the world’s leading atomic clocks with record accuracy over both air and optical fiber links.