Research Highlights

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.
 

In a new paper, JILA physicist Thomas Perkins collaborated with CU Biochemistry Prof. Marcello Sousa to dissect the mechanisms of how certain bacteria become more virulent. The research brings together the Perkins lab expertise in single-molecule studies and the Sousa lab expertise in the type III secretion system, a key component of Salmonella bacteria. 

JILA is the host of multiple centers within its campus. Some are National Science Foundation (NSF) funded and others funded by more private centers. Each center focuses on specific topics to advance the knowledge, education, and research on some of the biggest ideas within physics. 
 

Entangled particles have always fascinated physicists, as measuring one entangled particle can result in  a change in another entangled particle, famously dismissed as “spooky action at a distance” by Einstein. By now, physicists understand this strange effect and how to make use of it, for example to increase the sensitivity of measurements. However, entangled states are very fragile, as they can be easily disrupted by decoherence. Researchers have already created entangled states in atoms, photons, electrons and ions, but only recently have studies begun to explore  entanglement in gases of polar molecules. 

When looking within a quantum internet, the Sun Lab is looking at specifically photons. By entangling these photons, scientists tie little quantum knots between them, so they jointly represent the information to be delivered. The photons aren’t just paired off within these quantum knots. They’re connected to hundreds of other photons in a tree-shaped pattern. The robust redundancy of these photons means that scientists can still read the information, even if a few photons are lost.

For nearly a century, scientists have worked to unravel the mystery of dark matter—an elusive substance that spreads through the universe and likely makes up much of its mass, but has so far proven impossible to detect in experiments. Now, a team of researchers have used an innovative technique called “quantum squeezing” to dramatically speed up the search for one candidate for dark matter in the lab. 

For the first time, researchers can turn on an electric field to manipulate molecular interactions, get them to cool down further, and start to explore collective physics where all molecules are coupled to each other.

Building on their newfound ability to induce molecules in ultracold gases to interact with each other over long distances, JILA researchers have used an electric “knob” to influence molecular collisions and dramatically raise or lower chemical reaction rates.