About the Ye Group
Quantum science and precision metrology — quantum matter probed with novel light source
Our research group explores the frontier of light-matter interactions. Precisely controlled lasers enable our communications with microscopically engineered quantum systems of atoms and molecules. By preparing matter in specific quantum states, and using probe light with the longest coherence time and precisely controlled waveform, we strive to make fundamental scientific discoveries and develop new enabling technologies.
The strongly integrated development of scientific vision and experimental tools has enabled us to advance important topics in precision measurement, quantum many-body physics, quantum metrology, ultrafast science, and quantum science in general. For example, we employ quantum gas of strontium atoms confined in optical lattices to achieve best performing atomic clocks and investigate novel quantum dynamics, combining quantum metrology and quantum simulation. We prepare molecules in quantum degenerate gases to engineer tunable Hamiltonians for correlated quantum phenomena. These quantum-state prepared molecules are also explored for test of fundamental physics and study of quantum chemistry. Stable lasers and optical frequency combs are extending precision spectroscopy and extreme nonlinear optics from mid infrared to extreme ultraviolet, providing novel probes for large quantum systems, trace detection for health and environment, and new spectroscopy opportunities for nuclear transitions.
Research Areas
Our group explores many facets of ultracold strontium (Sr), emphasizing precision measurement and quantum state engineering and manipulation of atomic states. The group has achieved exquisite technical control via precision stabilization of lasers and the realization of ultracold atoms in optical lattices. Early on, we focused on precision measurements of Sr electronic transitions, which occur at optical frequencies, to explore the possibility of developing an optical atomic clock.
Since 1999 and 2000, there has been a remarkable convergence of the fields of ultrafast optics, opti cal frequency metrology, and precision laser spectroscopy — a convergence that our lab was privileged to help facilitate. A remarkable transformation took place in these fields as unprecedented advances occurred in the control of optical phases ranging from the ultrashort (femtoseconds) to laboratory time scales (seconds). Today, a single-frequency continuous optical field can achieve a phase coherence time exceeding 1 s. This phase coherence can be precisely transferred to the electric waveform of an ultrafast pulse train!
Molecules cooled to ultralow temperatures provide fundamental new insights to molecular interaction dynamics in the quantum regime. In recent years, researchers from various scientific disciplines such as atomic, optical, and condensed matter physics, physical chemistry, and quantum science have started working together to explore many emergent research topics related to cold molecules, including cold chemistry, strongly correlated quantum systems, novel quantum phases, and precision measurement. The exceedingly low energy regimes for ultracold molecules represent a new playground for chemical physics where quantum behaviors play a dominant role in molecular interaction and dynamics. Unique and complex molecular energy structure provides new opportunities for sensitive probe of fundamental physics. The anisotropic and long-range dipolar interactions add new ingredients to strongly correlated and collective quantum dynamics in many-body systems.
Research Highlights
New JILA Tools ‘Turn On’ Quantum Gases of Ultracold Molecules
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.
Read MoreJILA’s Electric ‘Knob’ Tunes Chemical Reaction Rates in Quantum Gas
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…
Read More
Advanced Atomic Clock Makes a Better Dark Matter Detector
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.
Read MoreTotal Ellipse of the SU(N)
A strangely shaped cloud of fermions revealed a record-fast way of cooling atoms for quantum devices.
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The Sisyphean Task of Cooling Molecules
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.
Read MoreTweezing a New Kind of Atomic Clock
Using optical tweezers, the Kaufman and Ye groups at JILA have achieved record coherence times, an important advance for optical clocks and quantum computing.
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How universal is universality?
New research from the Cornell Group suggests that the van der Waals universality may have limitations.
Read MoreKeep it steady
It's hard to read a clock with hands that wobble. The Ye Group has found a way to steady their optical atomic clock using a new cavity.
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Buckyballs Play by Quantum Rules
When the Ye group measured the total quantum state of buckyballs, we learned that this large molecule can play by full quantum rules. Specifically, this measurement resolved the rotational states of the buckyball,…
Read MoreThe First Quantum Degenerate Polar Molecules
Understanding chemistry requires understanding both molecules and quantum physics. The former defines the start and end of chemical reactions, the latter dictates the dynamics in between. JILA researchers now have a better understanding of both…
Read More
Turn it Up to 11 – The XUV Comb
With the advent of the laser, the fuzzy bands glowing from atoms transformed into narrow lines of distinct color. These spectral lines became guiding beacons visible from the quantum frontier. More than a half century later, we stand at the next…
Read MoreSame Clock. New Perspective.
We all know what a tenth of a second feels like. It’s a jiffy, a snap of the fingers, or a camera shutter click. But what does 14 billion years–the age of the universe–feel like? JILA’s atomic clock has the precision to measure the age of the…
Read More
The Energetic Adolescence of Carbon Dioxide
The reaction, at first glance, seems simple. Combustion engines, such as those in your car, form carbon monoxide (CO). Sunlight converts atmospheric water into a highly reactive hydroxyl radical (OH). And when CO and OH meet, one byproduct is…
Read MoreAnd, The Answer Is . . . Still Round
Why are we here? This is an age-old philosophical question. However, physicists like Will Cairncross, Dan Gresh and their advisors Eric Cornell and Jun Ye actually want to figure out out why people like us exist at all. If there had been the same…
Read More
The Clock that Changed the World
Imagine A Future . . . The International Moon Station team is busy on the Moon’s surface using sensitive detectors of gravity and magnetic and electric fields looking for underground water-rich materials, iron-containing ores, and other raw…
Read MoreQuantum Adventures with Cold Molecules
Researchers at JILA and around the world are starting a grand adventure of precisely controlling the internal and external quantum states of ultracold molecules after years of intense experimental and theoretical study. Such control of small…
Read More
Quantum Leaps
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…
Read MoreMolecules at the Quantum Frontier
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…
Read More
The Radical Comb-Over
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…
Read MoreStalking the Wild Molecules
The Ye group just solved a major problem for using molecular fingerprinting techniques to identify large, complex molecules: The researchers used an infrared (IR) frequency comb laser to identify four different large or complicated molecules. The…
Read More
The Ultramodern Molecule Factory: I. Doublons
The old JILA molecule factory (built in 2002) produced the world’s first ultracold polar molecules [potassium-rubidium (KRb)] in 2008. The old factory has been used since then for ultracold chemistry investigations and studies of the quantum…
Read MoreQuantum Baseball
The Ye and Rey groups have discovered the strange rules of quantum baseball in which strontium (Sr) atoms are the players, and photons of light are the balls. The balls control the players by not only getting the atoms excited, but also working…
Read More
Creative Adventures in Coupling
The Rey and Ye groups are in the midst of an extended collaboration on using the Ye group’s strontium (Sr) lattice clock for studies of spin-orbit coupling in pancake-like layers of cold Sr atoms. Spin-orbit coupling means an atom’s motion is…
Read MoreA Thousand Splendid Pairs
JILA’s cold molecule collaboration (Jin and Ye Groups, with theory support from the Rey Group) recently made a breakthrough in its efforts to use ultracold polar molecules to study the complex physics of large numbers of interacting quantum…
Read More
About Time
The Ye group has just improved the accuracy of the world’s best optical atomic clock by another factor of three and set a new record for clock stability. The accuracy and stability of the improved strontium lattice optical clocks is now about 2 x…
Read MoreA Bug’s Life
The Ye Group recently investigated what first appeared to be a “bug” in an experiment and made an unexpected discovery about a new way to generate high-harmonic light using molecular gases rather than gases of noble atoms. Graduate student Craig…
Read More
Atoms, Atoms, Frozen Tight in the Crystals of the Light, What Immortal Hand or Eye Could Frame Thy Fearful Symmetry?
Symmetries described by SU(N) group theory made it possible for physicists in the 1950s to explain how quarks combine to make protons and neutrons and JILA theorists in 2013 to model the behavior of atoms inside a laser. Now, the Ye group has…
Read MoreInvisible Rulers of Light
The Ye group has not only made two invisible rulers of extreme ultraviolet (XUV) light, but also figured out how to observe them with ordinary laboratory electronics. With this setup, the researchers were able to prove that the two rulers had…
Read More
Sky Clocks and the World of Tomorrow
Imagine a network of multiple clocks orbiting the Earth, not only reporting down to us, but also collaborating quantum mechanically among themselves to operate precisely in sync as a single global superclock, or world clock. The world clock is…
Read MoreDealing with Loss
There’s exciting news from JILA’s ultracold molecule collaboration. The Jin, Ye, Holland, and Rey groups have come up with new theory (verified by experiment) that explains the suppression of chemical reactions between potassium-rubidium (KRb)…
Read More
A Clockwork Blue Takes the Gold
JILA and NIST labs are well on the way to creating astonishingly accurate optical atomic clocks based on the neutral atoms strontium (Sr) and ytterbium (Yb). The new technologies are already capable of the most meticulous timekeeping in human…
Read MoreThe Dipolar Express
Physicists wonder about some pretty strange things. For instance, one burning question is: How round is the electron? While the simplest picture of the electron is a perfect sphere, it is possible that it is instead shaped like an egg. The egg…
Read More
The Great Spin Swap
Research associate Bo Yan and his colleagues recently observed spin exchanges in ultracold potassium-rubidium (KRb) molecules inside an optical lattice (a crystal of light formed by interacting laser beams). In solid materials, such spin…
Read MoreThe Magnificent Quantum Laboratory
Because quantum mechanics is crucial to understanding the behavior of everything in the Universe, one can understand key elements of the behavior of a neutron star by investigating the behavior of an atomic system in the laboratory. This is the…
Read More
Trapper Marmot and the Stone Cold Molecules
The Ye group has opened a new gateway into the relatively unexplored terrain of ultracold chemistry. Research associate Matt Hummon, graduate students Mark Yeo and Alejandra Collopy, newly minted Ph.D. Ben Stuhl, Fellow Jun Ye, and a visiting…
Read MoreThe Big Chill
The Ye and Bohn groups have made a major advance in the quest to prepare “real-world” molecules at ultracold temperatures. As recently reported in Nature, graduate students Ben Stuhl and Mark Yeo, research associate Matt Hummon, and…
Read More
The Most Stable Clock in the World
The world’s most stable optical atomic clock resides in the Ye lab in the basement of JILA’s S-Wing. The strontium-(Sr-)lattice clock is so stable that its frequency measurements don’t vary by more than 1 part in 100 quadrillion (1 x 10-17…
Read MoreNew Silicon Cavity Silences Laser Noise
Researchers from a German national laboratory, the Physikalisch-Technische Bundesanstalt (PTB) have collaborated with Fellow Jun Ye, Visiting Fellow Lisheng Chen (Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences), and…
Read More
The Indomitable Ruler of Light
The Ye group has created the world’s first “ruler of light” in the extreme ultraviolet (XUV). The new ruler is also known more formally as the XUV frequency comb. The comb consists of hundreds of equally spaced “colors” that function in precision…
Read MoreUltracold Polar Molecules to the Rescue!
Physicists would very much like to understand the physics underlying high-temperature superconductors. Such an understanding may lead to the design of room temperature superconductors for use in highly efficient and much lower-cost transmission…
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The Cold Case
The Ye group has built a cool new system for studying cold collisions between molecules. The system is far colder than a typical chemistry experiment that takes place at room temperature or hotter (300–500 K). But, it’s also much warmer than…
Read MoreThe Quantum Control Room
In 2008, the Ye and Jin groups succeeded in making ultracold potassium-rubidium (KRb) molecules in their ground state (See “Redefining Chemistry at JILA” in the Spring 2010 issue of JILA Light & Matter). Their next goal was to figure out how…
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Strontium Clock Performance Skyrockets
In 2008-2009, much to their amazement,researchers working on the Jun Ye group’s neutral Sr optical atomic clock discovered tiny frequency shifts caused by colliding fermions! They figured out that the clock laser was interacting slightly…
Read MoreThe Quantum Modeling Agency
“Nature is built quantum mechanically,” says Fellow Jun Ye, who wants to understand the connections between atoms and molecules in complex systems such as liquids and solids (aka condensed matter). He says that the whole Universe is made of…
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Deciphering Nature's Fingerprints
Fellow Jun Ye’s group has enhanced the molecular fingerprinting technique with the development of a mid-infrared (mid-IR) frequency comb. The new rapid-detection technique can now identify traces of a wider variety of molecules found in mixtures…
Read MoreRedefining Chemistry at JILA
Fellows Deborah Jin, Jun Ye, and John Bohn are exploring new scientific territory in cold-molecule chemistry. Experimentalists Jin and Ye and their colleagues can now manipulate, observe, and control ultralow-temperature potassium-rubidium (KRb)…
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Freeze Frame
The cold-molecule collaboration has developed a method for directly imaging ultracold ground-state KRb molecules. Their old method required the transfer of ultracold KRb molecules into a Feshbach state, which is sensitive to electric and magnetic…
Read MoreFermions in Collision?
According to the laws of quantum mechanics, identical fermions at very low temperatures can’t collide. These unfriendly subatomic particles, atoms, or molecules simply will not share the same piece of real estate with an identical twin. A few…
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The Right Stuff
In the summer of 2008, Fellow Jun Ye spent a couple of months at CalTech, where he ran into another visiting professor, former JILA Fellow Peter Zoller. Zoller left JILA in 1994 to become Professor of Physics at the University of Innsbruck (…
Read MoreA Quantum Leap for Precision Lasers
To be the best they can be, optical atomic clocks need better clock lasers — lasers that remain phase coherent a hundred times longer than the very best conventional lasers. For instance, light from the clock laser in Fellow Jun Ye’s lab can…
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Beams In Collision
Last year the Ye group conducted an actual laboratory astrophysics experiment. Graduate students Brian Sawyer, Ben Stuhl, and Mark Yeo, research associate Dajun Wang, and Fellow Jun Ye fired cold hydroxyl (OH) radicals into a linear decelerator…
Read MoreStalking the X-Ray Frequency Comb
Fellow Jun Ye’s group is methodically working its way toward the creation of an X-Ray frequency comb. Recently, senior research associate Thomas Schibli, graduate student Dylan Yost, Fellow Jun Ye, and colleagues from IMRA America, Inc. developed…
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Clock Talk
By late 2006, Fellow Jun Ye’s clock team had raised the accuracy of its strontium (Sr)-lattice atomic clock to be just shy of that of the nation’s primary time and frequency standard, the NIST-F1 cesium (Cs) fountain clock. Graduate students…
Read MoreThe Gravity of the Situation
What sort of experiment could detect the effects of quantum gravity, if it exists? Theories that go beyond the Standard Model of physics include a concept that links quantum interactions with gravity. Physicists would very much like to find…
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Every Breath You Take
With every breath you take, you breathe out carbon dioxide and roughly 1000 other different molecules. Some of these can signal the early onset of such diseases as asthma, cystic fibrosis, or cancer. Thanks to graduate student Mike Thorpe and his…
Read MoreLights, Magnets, Action!
When the Jin and Ye group collaboration wanted to investigate the creation of stable ultracold polar molecules, the researchers initially decided to make ultracold KRb (potassium-rubidium) molecules and then study their collision behavior. Making…
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Exploring a Cold New World
Researchers from the Ye, Bohn, and Greene groups are busy exploring a cold new world crawling with polar hydroxyl radical (OH) molecules. The JILA experimentalists have already discovered how to cool OH to “lukewarm” temperatures of 30 mK. They’…
Read MoreThe South Broadway Shootout
In the race to develop the world's best optical atomic clock, accuracy and precision are what count. Accuracy is the degree to which a measurement of time conforms to time's true value. Precision is a gauge of the exactness, or reproducibility,…
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Magic Light
"In the right light, in the right time, everything is extraordinary," according to photographer Aaron Rose. He could have just as easily been describing precision optical spectroscopy experiments recently conducted by Research Associates Tanya…
Read MorePartnership in Time
There's only one way to prove you've invented a better atomic clock: Come out on top of a comparison of your clock with one of the world's best atomic clocks: The NIST-F1 cesium fountain atomic clock, the nation's primary time and frequency…
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Molecular Fingerprinting
Science sleuths have a new and powerful method for identifying (and investigating) atoms and molecules, thanks to Graduate Student Mike Thorpe, Research Associate Kevin Moll, Senior Research Associate Jason Jones, Undergraduate Student Assistant…
Read MoreTime Traveling
Scientists in Fellow Jun Ye's lab are developing a high-precision optical atomic clock linked to super-narrow optical transitions in ultracold, trapped strontium atoms. However, unless the new clock is portable (it is not) or researchers figure…
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The Quest for Stability
Fellow Jan Hall has been working on stabilizing the frequency of lasers since the 1960s. Now, he, JILA Research Associate Mark Notcutt, Long-Sheng Ma (currently at BIPM in France), and Fellow Jun Ye have devised an improved, compact, and less…
Read MoreThe World's First UV Frequency Comb
Jason Jones, Kevin Moll, Mike Thorpe, and Jun Ye have generated the world's first precise frequency comb in the extreme ultraviolet (EUV) using a combination of an ultrafast mode-locked laser and a precision high-finesse optical cavity. The EUV…
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There's Strontium in the Clock
A high-powered JILA collaboration led by JILA Fellows Jun Ye and Chris Greene is making important progress toward developing an ultrastable, high-accuracy optical atomic clock. The new optical clock design will use a variety of laser sources…
Read MoreThe Power of Mirrors
Three years ago Jun Ye decided to apply an old idea for amplifying and stabilizing continuous-wave (cw) lasers to state-of-the-art ultrafast lasers. In 2002, Jason Jones, a postdoctoral fellow with Jun, analyzed whether the build-up cavities used…
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Highlights
JILA’s Electric ‘Knob’ Tunes Chemical Reaction Rates in Quantum Gas 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.
Buckyballs Play by Quantum Rules February 22, 2019
When the Ye group measured the total quantum state of buckyballs, we learned that this large molecule can play by full quantum rules. Specifically, this measurement resolved the rotational states of the buckyball, making it the largest and most complex molecule to be understood at this level.
The First Quantum Degenerate Polar Molecules January 18, 2019
Understanding chemistry requires understanding both molecules and quantum physics. The former defines the start and end of chemical reactions, the latter dictates the dynamics in between. JILA researchers now have a better understanding of both.
Turn it Up to 11 – The XUV Comb September 04, 2018
With the advent of the laser, the fuzzy bands glowing from atoms transformed into narrow lines of distinct color. These spectral lines became guiding beacons visible from the quantum frontier. More than a half century later, we stand at the next frontier. The elegant physics that will decode today’s mysteries (such as dark matter, dark energy, and the stability of our fundamental constants, to name a few) is still shrouded in shadows. But a new tool promises illumination.
Same Clock. New Perspective. March 26, 2018
We all know what a tenth of a second feels like. It’s a jiffy, a snap of the fingers, or a camera shutter click. But what does 14 billion years–the age of the universe–feel like? JILA’s atomic clock has the precision to measure the age of the universe to within a tenth of a second. That sort of precision is difficult to intuit. Yet, JILA’s atomic clock, which is the most precise clock in the world, continues to improve its precision. The latest jump in precision, of nearly 50 percent, came about from a new perspective.
The Energetic Adolescence of Carbon Dioxide January 12, 2018
The reaction, at first glance, seems simple. Combustion engines, such as those in your car, form carbon monoxide (CO). Sunlight converts atmospheric water into a highly reactive hydroxyl radical (OH). And when CO and OH meet, one byproduct is carbon dioxide (CO2) – a main contributor to air pollution and climate change.
And, The Answer Is . . . Still Round October 09, 2017
Why are we here? This is an age-old philosophical question. However, physicists like Will Cairncross, Dan Gresh and their advisors Eric Cornell and Jun Ye actually want to figure out out why people like us exist at all. If there had been the same amount of matter and antimatter created in the Big Bang, the future of stars, galaxies, our Solar System, and life would have disappeared in a flash of light as matter and antimatter recombined.
The Clock that Changed the World October 05, 2017
Imagine A Future . . . The International Moon Station team is busy on the Moon’s surface using sensitive detectors of gravity and magnetic and electric fields looking for underground water-rich materials, iron-containing ores, and other raw materials required for building a year-round Moon station. The station’s mission: launching colonists and supplies to Mars for colonization. Meanwhile, back on Earth, Americans are under simultaneous assault by three Category 5 hurricanes, one in the Gulf of Mexico and two others threatening the Caribbean islands. Hundreds of people are stranded in the rising waters, but thanks precision cell-phone location services and robust cell-tower connections in high wind, their rescuers are able to accurately pinpoint their locations and send help immediately.
Quantum Adventures with Cold Molecules September 07, 2017
Researchers at JILA and around the world are starting a grand adventure of precisely controlling the internal and external quantum states of ultracold molecules after years of intense experimental and theoretical study. Such control of small molecules, which are the most complex quantum systems that can currently be completely understood from the principles of quantum mechanics, will allow researchers to probe the quantum interactions of individual molecules with other molecules, investigate what happens to molecules during collisions, and study how molecules behave in chemical reactions.
Quantum Leaps December 21, 2016
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
Molecules at the Quantum Frontier December 19, 2016
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.
The Radical Comb-Over October 27, 2016
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.
Stalking the Wild Molecules May 04, 2016
The Ye group just solved a major problem for using molecular fingerprinting techniques to identify large, complex molecules: The researchers used an infrared (IR) frequency comb laser to identify four different large or complicated molecules. The IR laser-light absorption technique worked well for the first time with these larger molecules because the group combined it with buffer gas cooling, which precooled their samples to just a few degrees above absolute zero.
The Ultramodern Molecule Factory: I. Doublons April 20, 2016
The old JILA molecule factory (built in 2002) produced the world’s first ultracold polar molecules [potassium-rubidium (KRb)] in 2008. The old factory has been used since then for ultracold chemistry investigations and studies of the quantum behavior of ultracold molecules and the atoms that form them. The Jin-Ye group, which runs the molecule factory, is now wrapping up operations in the old factory with experiments designed to improve operations in the ultramodern factory, which is close to completion.
Quantum Baseball March 21, 2016
The Ye and Rey groups have discovered the strange rules of quantum baseball in which strontium (Sr) atoms are the players, and photons of light are the balls. The balls control the players by not only getting the atoms excited, but also working together. The players coordinate throwing and catching the balls. While this is going on, the balls can change the state of the players! Sometimes the balls even escape the quantum baseball game altogether and land on detectors in the laboratory.
Creative Adventures in Coupling January 28, 2016
The Rey and Ye groups are in the midst of an extended collaboration on using the Ye group’s strontium (Sr) lattice clock for studies of spin-orbit coupling in pancake-like layers of cold Sr atoms. Spin-orbit coupling means an atom’s motion is correlated with its spin. It occurs in everyday materials when negatively charged electrons move in response to electromagnetic fields inside a crystal.
A Thousand Splendid Pairs November 06, 2015
JILA’s cold molecule collaboration (Jin and Ye Groups, with theory support from the Rey Group) recently made a breakthrough in its efforts to use ultracold polar molecules to study the complex physics of large numbers of interacting quantum particles. By closely packing the molecules into a 3D optical lattice (a sort of “crystal of light”), the team was able to create the first “highly degenerate” gas of ultracold molecules.
About Time April 21, 2015
The Ye group has just improved the accuracy of the world’s best optical atomic clock by another factor of three and set a new record for clock stability. The accuracy and stability of the improved strontium lattice optical clocks is now about 2 x 10-18, or the equivalent of not varying from perfect time by more than one second in 15 billion years—more than the age of the Universe. Clocks like the Ye Group optical lattice clocks are now so exquisitely precise that they may have outpaced traditional applications for timekeeping such as navigation (GPS) and communications.
A Bug’s Life April 20, 2015
The Ye Group recently investigated what first appeared to be a “bug” in an experiment and made an unexpected discovery about a new way to generate high-harmonic light using molecular gases rather than gases of noble atoms. Graduate student Craig Benko and his colleagues in the Ye group were studying the interaction of light from an extreme ultraviolet (XUV) frequency comb with molecules of nitrous oxide, or laughing gas (N2O), when they noticed unusual perturbations in the laser spectrum.
Atoms, Atoms, Frozen Tight in the Crystals of the Light, What Immortal Hand or Eye Could Frame Thy Fearful Symmetry? August 18, 2014
Symmetries described by SU(N) group theory made it possible for physicists in the 1950s to explain how quarks combine to make protons and neutrons and JILA theorists in 2013 to model the behavior of atoms inside a laser. Now, the Ye group has observed a manifestation of SU(N≤10) symmetry in the magnetic behavior of strontium-87 (87Sr) atoms trapped in crystals of light created by intersecting laser beams inside a quantum simulator (originally developed as an optical atomic clock).
Invisible Rulers of Light June 22, 2014
The Ye group has not only made two invisible rulers of extreme ultraviolet (XUV) light, but also figured out how to observe them with ordinary laboratory electronics. With this setup, the researchers were able to prove that the two rulers had extraordinarily long phase-coherence time. This feat is so profound, it is nearly certain to transform the investigation of matter with extreme ultraviolet light, according to Ye’s colleagues in precision measurement and laser science. This research was reported online in Nature Photonics this week.
Sky Clocks and the World of Tomorrow June 13, 2014
Imagine a network of multiple clocks orbiting the Earth, not only reporting down to us, but also collaborating quantum mechanically among themselves to operate precisely in sync as a single global superclock, or world clock. The world clock is delivering the most precise timekeeping in all of human history—to every member nation regardless of politics, alliances, or behavior on the ground. Moreover, the world clock itself is virtually immune to sabotage and can peer under the surface of the Earth to uncover its detailed composition or out into space to reveal a better understanding of fundamental physical principles such as quantum mechanics and gravity.
Dealing with Loss March 05, 2014
There’s exciting news from JILA’s ultracold molecule collaboration. The Jin, Ye, Holland, and Rey groups have come up with new theory (verified by experiment) that explains the suppression of chemical reactions between potassium-rubidium (KRb) molecules in the KRb quantum simulator. The main reason the molecules do not collide and react is continuous measurement of molecule loss from the simulator.
A Clockwork Blue Takes the Gold January 22, 2014
JILA and NIST labs are well on the way to creating astonishingly accurate optical atomic clocks based on the neutral atoms strontium (Sr) and ytterbium (Yb). The new technologies are already capable of the most meticulous timekeeping in human history.
The Dipolar Express December 06, 2013
Physicists wonder about some pretty strange things. For instance, one burning question is: How round is the electron? While the simplest picture of the electron is a perfect sphere, it is possible that it is instead shaped like an egg. The egg shape would look a bit like a tiny separation of positive and negative charges. Physicists call this kind of charge separation an electric dipole moment, or EDM. The existence of an EDM in the electron or any other subatomic particle will have a profound impact on our understanding of the fundamental laws of physics.
The Great Spin Swap September 18, 2013
Research associate Bo Yan and his colleagues recently observed spin exchanges in ultracold potassium-rubidium (KRb) molecules inside an optical lattice (a crystal of light formed by interacting laser beams). In solid materials, such spin exchanges are the building blocks of advanced materials and exotic behavior.
The Magnificent Quantum Laboratory August 08, 2013
Because quantum mechanics is crucial to understanding the behavior of everything in the Universe, one can understand key elements of the behavior of a neutron star by investigating the behavior of an atomic system in the laboratory. This is the promise of the new quantum simulator in the Ye labs. It is a fully controllable quantum system that is being used as a laboratory to study the behavior of other less controllable and more poorly understood quantum systems.
Trapper Marmot and the Stone Cold Molecules April 01, 2013
The Ye group has opened a new gateway into the relatively unexplored terrain of ultracold chemistry. Research associate Matt Hummon, graduate students Mark Yeo and Alejandra Collopy, newly minted Ph.D. Ben Stuhl, Fellow Jun Ye, and a visiting colleague Yong Xia (East China Normal University) have built a magneto-optical trap (MOT) for yttrium oxide (YO) molecules. The two-dimensional MOT uses three lasers and carefully adjusted magnetic fields to partially confine, concentrate, and cool the YO molecules to transverse temperatures of ~2 mK. It is the first device of its kind to successfully laser cool and confine ordinary molecules found in nature.
The Big Chill December 19, 2012
The Ye and Bohn groups have made a major advance in the quest to prepare “real-world” molecules at ultracold temperatures. As recently reported in Nature, graduate students Ben Stuhl and Mark Yeo, research associate Matt Hummon, and Fellow Jun Ye succeeded in cooling hydroxyl radical molecules (*OH) down to temperatures of no more than five thousandths of a degree above absolute zero (5mK).
The Most Stable Clock in the World December 05, 2012
The world’s most stable optical atomic clock resides in the Ye lab in the basement of JILA’s S-Wing. The strontium-(Sr-)lattice clock is so stable that its frequency measurements don’t vary by more than 1 part in 100 quadrillion (1 x 10-17) over a time period of 1000 seconds, or 17 minutes.
New Silicon Cavity Silences Laser Noise September 12, 2012
Researchers from a German national laboratory, the Physikalisch-Technische Bundesanstalt (PTB) have collaborated with Fellow Jun Ye, Visiting Fellow Lisheng Chen (Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences), and graduate student Mike Martin to come up with a clever approach to reducing heat-related “noise” in interferometers.
The Indomitable Ruler of Light February 02, 2012
The Ye group has created the world’s first “ruler of light” in the extreme ultraviolet (XUV). The new ruler is also known more formally as the XUV frequency comb. The comb consists of hundreds of equally spaced “colors” that function in precision measurement like the tics on an ordinary ruler. The amazing thing about this ruler is that XUV colors have such short wavelengths they aren’t even visible to the human eye. The wavelengths of the XUV colors range from about 120 nm to about 50 nm — far shorter than the shortest visible light at 400 nm. “Seeing” the colors in the XUV ruler requires special instruments in the laboratory. With these instruments, the new ruler is opening up whole new vistas of research.
Ultracold Polar Molecules to the Rescue! September 14, 2011
Physicists would very much like to understand the physics underlying high-temperature superconductors. Such an understanding may lead to the design of room temperature superconductors for use in highly efficient and much lower-cost transmission networks for electricity. A technological breakthrough like this would drastically reduce world energy costs. However, this breakthrough requires a detailed understanding of the physics of high-temperature superconductivity.
The Cold Case September 02, 2011
The Ye group has built a cool new system for studying cold collisions between molecules. The system is far colder than a typical chemistry experiment that takes place at room temperature or hotter (300–500 K). But, it’s also much warmer than experiments that investigate ultracold-molecule collisions conducted at hundreds of billionths of a degree above absolute zero (0 K). The new system is known as “the cold molecule experiment” and operates at temperatures of approximately 5 K (-450 °F).
The Quantum Control Room March 21, 2011
In 2008, the Ye and Jin groups succeeded in making ultracold potassium-rubidium (KRb) molecules in their ground state (See “Redefining Chemistry at JILA” in the Spring 2010 issue of JILA Light & Matter). Their next goal was to figure out how to precisely control chemical reactions of these ultracold polar molecules by manipulating the quantum states of the reactants. But first the researchers had to discover how to calm those reactions down enough to study them. Under the conditions in which they were made (an optical trap allowing motion in all three dimensions), ultracold KRb molecules were so chemically reactive they disappeared almost as soon as they were formed.
Strontium Clock Performance Skyrockets February 03, 2011
In 2008-2009, much to their amazement,researchers working on the Jun Ye group’s neutral Sr optical atomic clock discovered tiny frequency shifts caused by colliding fermions! They figured out that the clock laser was interacting slightly differently with the Sr atoms inside a one-dimensional (pancake-shaped) trap. The light-atom interactions resulted in the atoms no longer being identical. And, once they were distinguishable, formerly unneighborly atoms were able to run into each other, compromising clock performance.
The Quantum Modeling Agency January 14, 2011
“Nature is built quantum mechanically,” says Fellow Jun Ye, who wants to understand the connections between atoms and molecules in complex systems such as liquids and solids (aka condensed matter). He says that the whole Universe is made of countless interacting particles, and it would be impossible to figure out the myriad connections between them one particle at a time, either theoretically or experimentally.
Deciphering Nature's Fingerprints November 24, 2010
Fellow Jun Ye’s group has enhanced the molecular fingerprinting technique with the development of a mid-infrared (mid-IR) frequency comb. The new rapid-detection technique can now identify traces of a wider variety of molecules found in mixtures of gases. It offers many advantages for chemical analysis of the atmosphere, climate science studies, and the detection of suspicious substances.
Redefining Chemistry at JILA May 06, 2010
Fellows Deborah Jin, Jun Ye, and John Bohn are exploring new scientific territory in cold-molecule chemistry. Experimentalists Jin and Ye and their colleagues can now manipulate, observe, and control ultralow-temperature potassium-rubidium (KRb) molecules in their lowest quantum-mechanical state. Theorist Bohn analyzes what the experimentalists see and predicts molecule behaviors under different conditions.
Freeze Frame April 17, 2010
The cold-molecule collaboration has developed a method for directly imaging ultracold ground-state KRb molecules. Their old method required the transfer of ultracold KRb molecules into a Feshbach state, which is sensitive to electric and magnetic fields. Thus researchers had to turn off the electric field and keep the magnetic field at a fixed value during the imaging process.
Fermions in Collision? September 07, 2009
According to the laws of quantum mechanics, identical fermions at very low temperatures can’t collide. These unfriendly subatomic particles, atoms, or molecules simply will not share the same piece of real estate with an identical twin. A few years back, researchers in the Ye lab considered this unneighborly behavior a big advantage in designing a new optical atomic clock based on an ensemble of identical 87Sr atoms.
The Right Stuff April 17, 2009
In the summer of 2008, Fellow Jun Ye spent a couple of months at CalTech, where he ran into another visiting professor, former JILA Fellow Peter Zoller. Zoller left JILA in 1994 to become Professor of Physics at the University of Innsbruck (Austria). Besides riding bikes together in the mountains, the two men engaged in happy and fruitful discussions about Ye’s work developing a strontium- (Sr-) based optical atomic clock and Zoller’s pioneering research on quantum computing. It took them a matter of a couple of weeks to come up with a basic theoretical framework for a quantum computer based on alkaline-earth metals such as Sr.
A Quantum Leap for Precision Lasers April 09, 2009
To be the best they can be, optical atomic clocks need better clock lasers — lasers that remain phase coherent a hundred times longer than the very best conventional lasers. For instance, light from the clock laser in Fellow Jun Ye’s lab can travel around the Earth 10 times before it loses coherence. However, realizing the potential of the lab’s optical clock requires that the laser light remain coherent for 1000 trips around the Earth. The brute force solution to this problem would be to operate the clock laser at 4 K. This approach would increase the cost, complexity, and size of the optical clock as well as rendering it impractical for space exploration and travel.
Beams In Collision February 20, 2009
Last year the Ye group conducted an actual laboratory astrophysics experiment. Graduate students Brian Sawyer, Ben Stuhl, and Mark Yeo, research associate Dajun Wang, and Fellow Jun Ye fired cold hydroxyl (OH) radicals into a linear decelerator equipped with an array of highly charged electrodes and slowed the OH molecules to a standstill. These molecules were then loaded into a permanent magnetic trap where they became the stationary target for collision studies. Next, Sawyer and his colleagues aimed supersonic beams of either helium (He) atoms or deuterium molecules (D2) at the OH molecules. They then studied the resulting low-energy collisions, which took place at temperatures of 80–300 K.
Stalking the X-Ray Frequency Comb July 09, 2008
Fellow Jun Ye’s group is methodically working its way toward the creation of an X-Ray frequency comb. Recently, senior research associate Thomas Schibli, graduate student Dylan Yost, Fellow Jun Ye, and colleagues from IMRA America, Inc. developed a high-performance, ultrastable fiber laser optical frequency comb. At the same time, Yost developed a clever method for getting coherent short-wavelength light out of a femtosecond enhancement cavity used with the fiber laser. These achievements have opened the door to the generation of frequency combs in the extreme ultraviolet (EUV) and soft X-ray regions of the electromagnetic spectrum.
Clock Talk April 10, 2008
By late 2006, Fellow Jun Ye’s clock team had raised the accuracy of its strontium (Sr)-lattice atomic clock to be just shy of that of the nation’s primary time and frequency standard, the NIST-F1 cesium (Cs) fountain clock. Graduate students Marty Boyd and Andrew Ludlow led the effort to improve the clock’s accuracy.
The Gravity of the Situation April 10, 2008
What sort of experiment could detect the effects of quantum gravity, if it exists? Theories that go beyond the Standard Model of physics include a concept that links quantum interactions with gravity. Physicists would very much like to find evidence of this coupling as these two branches of physics are not yet unified in a single theory that explains everything about our world.
Every Breath You Take April 02, 2008
With every breath you take, you breathe out carbon dioxide and roughly 1000 other different molecules. Some of these can signal the early onset of such diseases as asthma, cystic fibrosis, or cancer. Thanks to graduate student Mike Thorpe and his colleagues in Fellow Jun Ye’s group, medical practitioners may one day be able to identify these disease markers with a low-cost, noninvasive breath test. The new laser-based breath test is an offshoot of Thorpe’s research on cavity-enhanced direct optical frequency comb spectroscopy, a molecular fingerprinting technique reported in Science two years ago.
Lights, Magnets, Action! February 18, 2008
When the Jin and Ye group collaboration wanted to investigate the creation of stable ultracold polar molecules, the researchers initially decided to make ultracold KRb (potassium-rubidium) molecules and then study their collision behavior. Making the molecules required a cloud of incredibly cold K and Rb atoms, the ability to apply a magnetic field of just the right strength to induce a powerful attraction between the different kinds of atoms, and some low-frequency photons.
Exploring a Cold New World April 12, 2007
Researchers from the Ye, Bohn, and Greene groups are busy exploring a cold new world crawling with polar hydroxyl radical (OH) molecules. The JILA experimentalists have already discovered how to cool OH to “lukewarm” temperatures of 30 mK. They’ve precisely measured four OH transition frequencies that will help physicists determine whether the fine structure constant has changed in the past 10 billion years.
The South Broadway Shootout September 29, 2006
In the race to develop the world's best optical atomic clock, accuracy and precision are what count. Accuracy is the degree to which a measurement of time conforms to time's true value. Precision is a gauge of the exactness, or reproducibility, of the measurements. By definition, a high-precision clock must be extremely stable.
Magic Light July 11, 2006
"In the right light, in the right time, everything is extraordinary," according to photographer Aaron Rose. He could have just as easily been describing precision optical spectroscopy experiments recently conducted by Research Associates Tanya Zelevinsky and Tetsuya Ido, Graduate Students Martin Boyd and Andrew Ludlow, Fellow Jun Ye and collaborators from Poland's Instytut Fizyki and NIST's Atomic Physics Division.
Partnership in Time June 17, 2006
There's only one way to prove you've invented a better atomic clock: Come out on top of a comparison of your clock with one of the world's best atomic clocks: The NIST-F1 cesium fountain atomic clock, the nation's primary time and frequency standard. NIST-F1 is so accurate it won't gain or lose a second in more than 60 million years.
Molecular Fingerprinting April 26, 2006
Science sleuths have a new and powerful method for identifying (and investigating) atoms and molecules, thanks to Graduate Student Mike Thorpe, Research Associate Kevin Moll, Senior Research Associate Jason Jones, Undergraduate Student Assistant Ben Safdi, and Fellow Jun Ye. The new method allows them to study molecular vibrations, rotations, and collisions as well as temperature changes and chemical reactions.
Time Traveling October 02, 2005
Scientists in Fellow Jun Ye's lab are developing a high-precision optical atomic clock linked to super-narrow optical transitions in ultracold, trapped strontium atoms. However, unless the new clock is portable (it is not) or researchers figure out how to accurately transmit its clock signal over a fiber optic network to NIST, the legendary strontium clock will not be able to help the world keep better time.
The Quest for Stability August 10, 2005
Fellow Jan Hall has been working on stabilizing the frequency of lasers since the 1960s. Now, he, JILA Research Associate Mark Notcutt, Long-Sheng Ma (currently at BIPM in France), and Fellow Jun Ye have devised an improved, compact, and less expensive method for stabilizing lasers. The new method is based on a small, vertically mounted optical cavity (shown on the right). Because the cavity is supported exactly in the middle, the top and bottom halves change in length by equal and opposite amounts in response to vibrations.
The World's First UV Frequency Comb April 10, 2005
Jason Jones, Kevin Moll, Mike Thorpe, and Jun Ye have generated the world's first precise frequency comb in the extreme ultraviolet (EUV) using a combination of an ultrafast mode-locked laser and a precision high-finesse optical cavity. The EUV frequency comb consists of regularly spaced sharp lines that extend into the EUV region of the electromagnetic spectrum.
There's Strontium in the Clock April 03, 2005
A high-powered JILA collaboration led by JILA Fellows Jun Ye and Chris Greene is making important progress toward developing an ultrastable, high-accuracy optical atomic clock. The new optical clock design will use a variety of laser sources including a femtosecond comb and a diode laser stabilized with an optical cavity, which, in turn, is locked to a narrow energy level transition in ultracold strontium atoms.
The Power of Mirrors April 03, 2005
Three years ago Jun Ye decided to apply an old idea for amplifying and stabilizing continuous-wave (cw) lasers to state-of-the-art ultrafast lasers. In 2002, Jason Jones, a postdoctoral fellow with Jun, analyzed whether the build-up cavities used to amplify cw laser outputs could be modified to work with ultrafast, mode-locked lasers. His detailed calculations suggested that it would be possible but technically demanding.
In the Spotlight
The Micius Quantum Prize recognizes significant scientific advances ranging from the early conceptual contributions to the recent experimental breakthroughs. The Micius Quantum Prize 2020 focuses on the broadly defined field of quantum metrology, recognizing scientific advances ranging from early conceptual contributions to experimental breakthroughs. The laureates this year are Carlton Caves, Hidetoshi Katori, and Jun Ye.
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Led by CU Boulder and designed to push the frontiers of quantum sensing, Quantum Systems through Entangled Science and Engineering (Q-SEnSE) involves 37 researchers from 11 institutes located in 6 different states (and one collaborating from Europe).
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JILA fellow Jun Ye has been named Highly Cited Researcher for 2020 by Clarivate Analytics. Ye has been awarded the Highly Cited Researcher in the field of physics every year since 2014.
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Quantum science has the potential to further revolution technology in several fields, from computing to communication. As a world-renowned leader in the field, JILA Fellow Jun Ye will advise U.S. leaders on ways to bring these advances out of the lab and into real-world applications.
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Map | JILA Phone: 303-492-7789 | Address: 440 UCB, Boulder, CO 80309