Research Highlights

The Regal group recently met the challenge of measurements in an extreme situation with a device called an interferometer. The researchers succeeded by using creative alterations to the device itself and quantum correlations. Quantum correlations are unique, and often counterintuitive, quantum mechanical interactions that occur among quantum objects such as photons and atoms. The group exploited these interactions in the way they set up their interferometer, and improved its ability to measure tiny motions using photons (particles of light).

The first results are in from a new search for the axion, a hypothetical particle that may constitute dark matter. Researchers in the Haloscope At Yale Sensitive to Axion Cold Dark Matter (HAYSTAC) recently looked for evidence of the axion, but so far they have found none in the small 100 MHz frequency range between 5.7 and 5.8 GHz.

Dennis Gardner and his coworkers in the Kapteyn-Murnane group accomplished two major breakthroughs in imaging tiny structures much too small to be seen with visible light microscopes: (1) for the first time in the extreme ultraviolet (EUV) or soft X-ray region, they achieved a resolution smaller than the wavelength of the light; and (2) for the first time, they obtained high resolution quantitative imaging of near periodic tiny objects (structures with repetitive features).

The lovely Crab Nebula was created by a supernova and its spinning-neutron-star remnant known as a pulsar. Pulsar wind nebulae, such as the Crab, shine because they contain plasmas of charged particles, such as electrons and positrons, traveling at near the speed of light. A key question in astrophysics has long been: What process accelerates some of the charged particles in plasmas to energies much higher than the average particle energy, giving them near light speeds?

The Perkins group continues to extend the performance of its unique Atomic Force Microscope (AFM) technology, revealing for the first time a dozen new short-lived intermediate states in the folding and unfolding of a membrane protein that controls the exchange of chemicals and ions into and out of living cells. Measuring the energetics and dynamics of membrane proteins is crucial to understanding normal physiology and disease, and the Perkins group’s observation of multiple new folding/unfolding states shines new light on these cellular “gatekeepers.”

In the Ye group’s new quantum simulation experiment, cold strontium atoms, which are analogs of electrons, are allowed to tunnel between the pancakes that confine the atoms with laser light. Because the atoms moving in an array of pancakes are analogs of electrons moving in solids, such studies are expected to shed light on the complex physics of metals and other solids. Credit:  The Ye group and Steve Burrows, JILA

Deborah Jin, Jun Ye, and their students wrote a review during the summer of 2016 for Nature Physics highlighting the accomplishments and future directions of the relatively new field of ultracold-molecule research. The field was pioneered by the group’s creation of the world’s first gas of ultracold potassium-rubidium (KRb) molecules in 2008.

Astrophysicist Jeff Linsky and his colleagues recently created a sophisticated mathematical model of the outer atmosphere of the small M-dwarf star called GJ832. The new model fits well with spectral observations of the star made with the Hubble Space Telescope (HST). This accomplishment bodes well for two reasons: First, it provides a tool for better understanding M-dwarf stars––the most common type of star in our galaxy.

The Rey and Ye groups discovered the strange rules of quantum baseball earlier this year. But now, quantum baseball games happen faster, and players (dipolar particles) are no longer free to move or stand wherever they want. Players must not only be stronger to jump and catch the balls (photons), but also more organized. At the same time, they must be good spinners. And, only a small amount of disorder is tolerated! The fast spinning of the players and their fixed positions have made quantum baseball a whole new game!

Galaxy mergers routinely occur in our Universe. And, when they take place, it takes years for the supermassive black holes at their centers to merge into a new, bigger supermassive black hole. However, a very interesting thing can happen when two black holes get close enough to orbit each other every 3–4 months, something that happens just before the two black holes begin their final desperate plunge into each other. 

Graduate student Mike Thompson of the Weber group wants to understand the basic science of taking carbon dioxide (CO₂) produced by burning fossil fuels and converting it back into useful fuels. People could then use these fuels to generate electricity, heat homes and office buildings, power automobiles and trains, fly airplanes, and drive the industrial processes of modern life.

For a long time, there’s been a mystery concerning how tiny interactions between individual atoms could lead to really big changes in a whole cloud of independent-minded particles. The reason this behavior is mysterious is that the atoms interact weakly, and only when they are very close to each other. Yet, the atoms clear across the cloud seem to know when it’s time to participate in some big-deal quantum behavior such as simultaneously all changing the direction of their spins.

Far-red fluorescent light emitted from proteins could one day illuminate the inner workings of life. But before that happens, scientists like Fellow Ralph Jimenez must figure out how fluorescent proteins’ light-emitting structures work. As part of this effort, Jimenez wants to answer a simple question: How do we design red fluorescent proteins to emit longer-wavelength, or redder, light?

Using frequency comb spectroscopy, the Ye group has directly observed transient intermediate steps in a chemical reaction that plays a key role in combustion, atmospheric chemistry, and chemistry in the interstellar medium. The group was able to make this first-ever measurement because frequency combs generate a wide range of laser wavelengths in ultrafast pulses. These pulses made it possible for the researchers to “see” every step in the chemical reaction of OH + CO → HOCO → CO2 + H.

The Nesbitt group has invented a nifty technique for exploring the physics and chemistry of a gas interacting with molecules on the surface of a liquid. The group originally envisioned the technique because it’s impossible to overestimate the importance of understanding surface chemistry. For instance, ozone depletion in the atmosphere occurs because of chemical reactions of hydrochloric acid on the surface of ice crystals and aerosols in the upper atmosphere. Interstellar chemistry takes place on the surface of tiny grains of dust.

Exciting new theory from the Rey group reveals the profound effects of electron interactions on the flow of electric currents in metals. Controlling currents of strongly interacting electrons is critical to the development of tomorrow’s advanced microelectronics systems, including spintronics devices that will process data faster, use less power than today’s technology, and operate in conditions where quantum effects predominate.

Fellow Mitch Begelman’s new theory says it’s possible to form stars while a supermassive black hole consumes massive amounts of stellar debris and other interstellar matter. What’s more, there’s evidence that this is exactly what happened around the black hole at the center of the Milky Way some 4–6 million years ago, according to Associate Fellow Ann-Marie Madigan.

Graduate student Greg Salvesen, JILA Collaborator Jake Simon (Southwest Research Institute), and Fellows Phil Armitage and Mitch Begelman decided they wanted to figure out why swirling disks of gas (accretion disks) around black holes often appear strongly magnetized. They also wanted to figure out the mechanism that allowed this magnetization to persist over time.

Newly minted Ph.D. Ming-Guang Hu and his colleagues in the Jin and Cornell groups recently investigated immersing an impurity in a quantum bath consisting of a Bose-Einstein condensate, or BEC. The researchers expected the strong impurity-boson interactions to “dress” the impurity, i.e., cause it to get bigger and heavier. In the experiment, dressing the impurity resulted in it becoming a quasi particle called a Bose polaron.

Physics education researchers from the University of Colorado Boulder and the University of Maine recently showed that students troubleshooting a malfunctioning electric circuit successfully tackled the problem by using models of how the circuit ought to work. The researchers confirmed this approach by analyzing videotapes of eight pairs of students talking aloud about their efforts to diagnose and repair a malfunctioning electric circuit. The circuits had not just one, but two problems. Both problems had to be corrected for the circuit to work properly.