Research Highlights

Precision Measurement | Quantum Information Science & Technology
Controlling a Quantum Classroom: New Insights into the Spin-Dynamics of Molecules
A 2D itinerant spin system with polar molecules interacting and colliding
Published: February 01, 2023

Quantum gases of interacting molecules can exhibit unique dynamics. JILA and NIST Physicist Jun Ye has spent years of research to reveal, probe, and control these dynamics with potassium-rubidium molecules. In a new article published in Nature, Ye and his team of researchers describe having combined two threads of previous research—spin and motional dynamics—to reveal rich many-body and collisional physics that are controllable in the laboratory. 

PI: Jun Ye
Read More
Precision Measurement | Quantum Information Science & Technology
A Magic Balance in Optical Lattice Clocks
Local interactions in the same lattice pull clock frequency negative while interactions between atoms on neighboring lattice sites pull clock frequency positive. By adjusting the atomic confinement, or tightness, of the lattice, researchers can balance these two counteracting forces to increase clock sensitivity.
Published: October 12, 2022

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.

PI: Ana Maria Rey | PI: Jun Ye
Read More
Quantum Information Science & Technology
A Look at Colorado's Quantum Revolution
Child wears a helmet made up of more than 100 OPM sensors.
Published: June 28, 2022

More than 400 years later, scientists are in the midst of an equally-important revolution. They’re diving into a previously-hidden realm—far wilder than anything van Leeuwenhoek, known as the “father of microbiology,” could have imagined. Some researchers, like physicists Margaret Murnane and Henry Kapteyn, are exploring this world of even tinier things with microscopes that are many times more precise than the Dutch scientist’s. Others, like Jun Ye, are using lasers to cool clouds of atoms to just a millionth of a degree above absolute zero with the goal of collecting better measurements of natural phenomena. 

PI: Jun Ye | PI: Cindy Regal | PI: Margaret Murnane | PI: Henry Kapteyn | PI: Ana Maria Rey
Read More
Precision Measurement | Quantum Information Science & Technology
An Atomic Game of Duck, Duck, Goose
Selected atoms (green) within doubly occupied sites of a 2D "Fermi Sea" are excited by a polarized laser pulse. Pauli blocking prevents decay of the excited atoms (red) as they can only decay into unoccupied sites (black).
Published: April 15, 2022

Physics has always been a science of rules. In many situations, these rules lead to clear and simple theoretical predictions which, nevertheless, are hard to observe in actual experimental settings where other confounding effects may obscure the desired phenomena. For JILA and NIST Fellows Ana Maria Rey and Jun Ye, one type of phenomena they are especially interested in observing are the interactions between light and atoms, especially those at the heart of the decay of an atom prepared in the excited state. “If you have an atom in the excited state, the atom will eventually decay to the ground state while emitting a photon,” explained Rey. “This process is called spontaneous emission.” The spontaneous emission rate can be manipulated by scientists, making it longer or shorter, depending on the experimental conditions. Many years ago it was predicted that one way to suppress or slow down spontaneous emission was by applying a special type of statistics known as Fermi statistics which prevents two identical fermions from being in the same quantum state, known as the Pauli Exclusion Principle

This principle is similar to a game of Duck, Duck, Goose, where two individuals fight over an open spot in a circle in order to avoid being “it.” Like children in this game, the atoms must find an empty quantum state to decay into. If they cannot find an empty state, interesting things begin to happen. “If an excited atom wants to decay, but the ground state is already filled, then the decay is “Pauli blocked” and the atom will stay in the excited state longer, or even forever,” Rey said. Nevertheless, the experimental observation of this effect happened to be challenging.  It was not until last year  that the Ye group observed Pauli blocking of radiation for the first time indirectly by measuring the light scattered by the atoms—but a direct observation of Pauli blocking by measuring  the lifetime of atoms in the steady state was lacking. More recently, Ye’s and Rey’s groups collaborated in a joint study, and were able to find an appropriate experimental setting where they were able to observe Pauli blocking of spontaneous emission by direct measurements of the excited state population. The results have been published in the journal Physical Review Letters. 

PI: Jun Ye | PI: Ana Maria Rey
Read More
Precision Measurement | Quantum Information Science & Technology
Electrifying Molecular Interactions
A depiction showing the interaction between ultra cold compressed 2D gas layers of KRb molecules
Published: March 17, 2022

Worldwide, many researchers are interested in controlling atomic and molecular interactions. This includes JILA and NIST fellows Jun Ye and Ana Maria Rey, both of whom have spent years researching interacting potassium-rubidium (KRb) molecules, which were originally created in a collaboration between Ye and the late Deborah Jin. In the newest collaboration between the experimental (Ye) and theory (Rey) groups, the researchers have developed a new way to control two-dimensional gaseous layers of molecules, publishing their exciting new results in the journal Science.

PI: Jun Ye | PI: Ana Maria Rey
Read More
Atomic & Molecular Physics | Precision Measurement | Quantum Information Science & Technology
JILA Atomic Clocks Measure Einstein’s General Relativity at Millimeter Scale
JILA researchers measured time dilation, or how an atomic clock's ticking rate varied by elevation, within this tiny cloud of strontium atoms.
Published: February 16, 2022

JILA physicists have measured Albert Einstein’s theory of general relativity, or more specifically, the effect called time dilation, at the smallest scale ever, showing that two tiny atomic clocks, separated by just a millimeter or the width of a sharp pencil tip, tick at different rates.

The experiments, described in the Feb. 17 issue of Nature, suggest how to make atomic clocks 50 times more precise than today’s best designs and offer a route to perhaps revealing how relativity and gravity interact with quantum mechanics, a major quandary in physics.
 

PI: Jun Ye
Read More
Atomic & Molecular Physics | Precision Measurement | Quantum Information Science & Technology
Colorado Congressman Joe Neguse tours JILA
Top: From left to right, physicist Margaret Murnane, Rep. Joe Neguse, Chancellor Philip DiStefano and CU President Todd Saliman in Murnane's lab at JILA; bottom: Murnane discusses the promise of new microscope technologies during the JILA tour. (Credits: Glenn Asakawa/CU Boulder)
Published: December 20, 2021

Last week, U.S. Rep. Joe Neguse got a first-hand look at the future of ultrafast lasers, record-setting clocks, and quantum computers on the CU Boulder campus. Neguse visited the university Thursday to tour facilities at JILA, a research partnership between CU Boulder and the National Institute of Standards and Technology (NIST).

PI: Jun Ye | PI: Margaret Murnane
Read More
Atomic & Molecular Physics | Quantum Information Science & Technology
Atomic Musical Chairs
A representation of light scattering within the 3D gas, called the Fermi Sea
Published: November 18, 2021

How atoms interact with light reflects some of the most basic principles in physics. On a quantum level, how atoms and light interact has been a topic of interest in the worldwide scientific community for many years. Light scattering is a process where incoming light excites an atom to a higher-lying energy state from which it subsequently decays back to its ground state by reemitting a quantum of light. In the quantum realm, there are many factors that affect light scattering. In a new paper published in Science, JILA and NIST Fellow Jun Ye and his laboratory members report on how light scattering is affected by the quantum nature of the atoms, more specifically, thequantum statistical rule such as the Pauli Exclusion Principle.

PI: Jun Ye
Read More
Quantum Information Science & Technology | Other
Help Wanted: How to Build a Prepared and Diverse Quantum Workforce
Silhouettes of workforce
Published: October 21, 2021

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. 

PI: Heather Lewandowski | PI: Jun Ye | PI: Margaret Murnane
Read More
Quantum Information Science & Technology
Don’t React, Interact: Looking Into Inert Molecular Gases
The dipolar interactions within a molecular gas
Published: October 11, 2021

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.

PI: John Bohn | PI: Jun Ye
Read More
Atomic & Molecular Physics | Biophysics | Chemical Physics
When Breath Becomes Data
Model of frequency comb filtering breath molecules
Published: October 05, 2021

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).

PI: Jun Ye | PI: David Nesbitt
Read More
Precision Measurement | Quantum Information Science & Technology
Wiggles in Time: The Search for Dark Matter Continues
Model of eEDM
Published: June 17, 2021

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. 

PI: Jun Ye | PI: Eric Cornell | PI: Konrad Lehnert
Read More
Atomic & Molecular Physics | Precision Measurement
NIST Team Compares 3 Top Atomic Clocks With Record Accuracy Over Both Fiber and Air
Model of the atomic clock comparisons
Published: March 24, 2021

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.
 

PI: Jun Ye
Read More
Quantum Information Science & Technology
Molecules in Flat Lands: an Entanglement Paradise
Model of the quantum gas pancake
Published: March 18, 2021

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. 

PI: Ana Maria Rey | PI: Jun Ye
Read More
Atomic & Molecular Physics | Laser Physics | Quantum Information Science & Technology
New JILA Tools ‘Turn On’ Quantum Gases of Ultracold Molecules
False-color image of a gas of potassium-rubidium polar molecules
Published: December 12, 2020

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.

PI: Jun Ye
Read More
Atomic & Molecular Physics | Laser Physics | Quantum Information Science & Technology
JILA’s Electric ‘Knob’ Tunes Chemical Reaction Rates in Quantum Gas
Optical lattice
Published: December 10, 2020

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.

PI: Jun Ye
Read More
Atomic & Molecular Physics | Laser Physics | Quantum Information Science & Technology
Advanced Atomic Clock Makes a Better Dark Matter Detector
Cartoon clock looks for dark matter.
Published: November 30, 2020

JILA researchers have used a state-of-the-art atomic clock to narrow the search for elusive dark matter, an example of how continual improvements in clocks have value beyond timekeeping.

PI: Jun Ye
Read More
Atomic & Molecular Physics
Total Ellipse of the SU(N)
SU(N) fermions display unique properties.
Published: September 11, 2020

A strangely shaped cloud of fermions revealed a record-fast way of cooling atoms for quantum devices.

PI: Jun Ye | PI: Ana Maria Rey
Read More
Atomic & Molecular Physics
The Sisyphean Task of Cooling Molecules
Gray molasses cooling in YO molecules
Published: June 03, 2020

Bringing molecules down to ultracold temperatures takes a mythic approach, but the Ye Group finds that their new scheme can hold up under tough conditions.

PI: Jun Ye
Read More
Atomic & Molecular Physics | Laser Physics | Precision Measurement
Tweezing a New Kind of Atomic Clock
optical tweezers holding atoms, connected by a clock
Published: February 16, 2020

Using optical tweezers, the Kaufman and Ye groups at JILA have achieved record coherence times, an important advance for optical clocks and quantum computing.

PI: Adam Kaufman | PI: Jun Ye
Read More