News & Highlights

Research Highlights

Missing Link
Published: 07-10-2008
The Jin group recently came up with the first strong experimental link between superfluidity in ultracold Fermi gases and superconductivity in metals. What’s more, this feat was accomplished with photoemission spectroscopy, a tried-and-true technique that has been used for more than 100 years to study solids. This technique has been instrumental in revealing the properties of superconductors. It is just beginning to be developed in ultracold Fermi gases, where it could prove to be just as...
Bragging Rites
Published: 07-10-2008
What happens to a Bose-Einstein condensate (BEC) when its atoms interact strongly? One possibility for large attractive interactions is that the condensate shrinks and then explodes, as the Cornell and Wieman groups discovered in 2001. Another possibility for large repulsive interactions is behavior analogous to that of superfluid liquid helium. If superfluid liquid heliumlike dynamics could be observed and probed in strongly interacting atomic BECs, it would help bridge the gap between the...
Stalking the X-Ray Frequency Comb
Published: 07-09-2008
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...
Splash 2
Published: 07-07-2008
For many years, chemists have explored the differences between liquids and solids. One difference is that liquid surfaces tend to be softer than solid surfaces (from the perspective of molecules crashing onto them). Another difference is that the surface of at least one oily liquid (perfluorinated polyether, or PFPE) actually gets stickier as it gets hotter, according to a new study by graduate student Brad Perkins and Fellow David Nesbitt. This behavior contrasts with solid surfaces, which...
The Gravity of the Situation
Published: 04-10-2008
  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. Many physicists believe it would be very difficult to detect connections between quantum mechanics and...
Clock Talk
Published: 04-10-2008
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. But then, the clock team had to spend another year proving that its imporved clock would neither gain nor lose a second in more than 200 million years — thus surpassing the NIST-F1...
Every Breath You Take
Published: 04-02-2008
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...
Lights, Magnets, Action!
Published: 02-18-2008
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. The researchers...
One Ring to Rule Them All
Published: 02-12-2008
Benzene has a special ring structure that allows some of its electrons to be shared among all six carbon atoms in the ring. It turns out that chemists like Fellow J. Mathias Weber can adjust the charge density in the ring by exchanging hydrogen (H) atoms in the ring with other atoms or groups of atoms. Such exchanges can change the charge pattern in the ring "seen" by neighboring molecules. The interaction based on the charge distribution isn’t the whole story, however. Often, negatively...
DNA: Force of Nature
Published: 02-07-2008
The Perkins group is helping to develop DNA as a force standard for the nano world. Polymers of DNA act like springs, and DNA's elasticity may one day provide a force standard from 0.1–10 piconewtons (pN). One pN is the force exerted when 1 mW of light reflects off a mirror or the approximate weight of one hundred E. coli cells. DNA is an excellent candidate for a force standard because its double helix is reproduced with exquisite fidelity, which allows researchers (or cells) to build it...
Bohr + Schrödinger = Students Win
Published: 01-10-2008
A solid understanding of the structure and behavior of atoms is important for understanding the physical world, from the basic building blocks of nature to the inner workings of modern technology. However, education researchers have expressed different opinions regarding the best way to teach students the ins and outs of atoms. In particular, some have even recommended doing away with teaching the older and simpler Bohr model, asserting that it inhibits students’ ability to understand the...
Reflection Grisms
Published: 10-01-2007
Fellows Ralph Jimenez and Henry Kapteyn and their groups recently helped develop optical technology that will make femtosecond laser experiments much simpler to perform, opening the door to using such lasers in many more laboratories. The technology, which employs reflection grisms as laser pulse compressors, has been patented and is now available commercially. A reflection grism consists of metal reflection grating mounted on one face of a prism. Properly designed, they can compensate for...
Echoes of Hidden Worlds
Published: 10-01-2007
In Fellow Steve Cundiff’s lab, echoes of light are illuminating the quantum world. Former Graduate Student Gina Lorenz used a technique known as echo peak shift spectroscopy to probe the interactions of potassium atoms in a dense vapor. Research Associate Sam Carter then used the same method to investigate the interactions of excitons confined in two-dimensional semiconductor quantum wells. In semiconductors, an exciton forms when light promotes an electron from the valence band to the...
A Failure to Communicate
Published: 06-15-2007
In the quantum world inside Fellow Eric Cornell’s lab, communication occurs across a two-dimensional lattice array of Bose-Einstein condensates (BECs) when atoms tunnel out of superatoms (made from about 7000 garden-variety rubidium (Rb) atoms) into neighboring BECs. This communication keeps the array coherent, i.e., the phases of all condensates remain locked to each other. But something interesting happens when the tiny superatoms stop communicating among themselves. Vortices form. And how...
The Second Wave
Published: 04-12-2007
A second wave has appeared on the horizon of ultracold atom research. Known as the p-wave, it is opening the door to probing rich new physics, including unexplored quantum phase transitions. The first wave of ultracold atom research focused on s-wave pairing between atoms, where the “s” meant the resultant molecules are not rotating. In contrast, p-waves involve higher-order pairing where the atoms do rotate around each other. p-wave studies promise to expand and enhance the understanding of...
Exploring a Cold New World
Published: 04-12-2007
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.1 In a recent and productive collaboration between JILA experimentalists and theorists...
Deep Sea Diving
Published: 04-10-2007
A Fermi sea forms at ultracold temperatures when fermions in a dilute gas stack up in the lowest possible energy states, with two fermions in each state, one spin up and one spin down. New analytic techniques for diving headfirst into the fundamental physics of this exotic form of matter were recently developed by graduate students Seth Rittenhouse and Javier von Stecher, Fellow Chris Greene, and former postdoc Mike Cavagnero, now at the University of Kentucky. Seth got the ball rolling (so to...
Warm Side of the Force
Published: 04-10-2007
Small changes in the quantum fluctuations of free space are responsible for a variety of curious phenomena: a gecko’s ability to walk across ceilings, the evaporation of black holes via Hawking radiation, and the fact that warmer surfaces can be stickier than cold ones in micro- and nanoscale electromechanical systems (MEMS and NEMS). The tendency of tiny parts to stick together is a consequence of the Casimir force. A related attractive force, called the Casimir-Polder force, occurs between an...
Tunnel Vision
Published: 03-02-2007
A key challenge in developing new nanotechnologies is figuring out a fast, low-noise technique for translating small mechanical motions into reasonable electronic signals. Solving this problem will one day make it possible to build electronic signal processing devices that are much more compact than their purely electronic counterparts. Much sooner, it will enable the design of advanced scanning tunneling microscopes that operate hundreds to thousands of times faster than current models....
Spin City
Published: 02-10-2007
Researchers are investigating a new kind of microelectronics called spintronics. These devices will rely on the spindependent behavior of electrons in addition to (or even instead of) conventional charge-based circuitry. Researchers in physics and engineering anticipate that these devices will process data faster, use less power than today's conventional semiconductor devices, and work well in nanotechnologies, where quantum effects predominate. Spin-FETs (field effect transistors), spin-LEDs...
JILA Physicists Investigating Atomtronics
Published: 02-01-2007
JILA physicists are investigating complex and interesting materials, circuits, and devices based on ultracold atoms instead of electrons. Collectively known as atomtronics, they have important theoretical advantages over conventional electronics, including (1) superfluidity and superconductivity, (2) minimal thermal noise and instability, and (3) coherent flow. With such characteristics, atomtronics could play a key role in quantum computing, nanoscale amplifiers, and precision sensors. A...
Imaging the Nanoworld
Published: 10-28-2006
If you want to "see" physical objects whose dimensions are measured in nanometers and simultaneously probe the electronic structure of the atoms, molecules, and surfaces populating this nanoworld, you just might have to invent a new microscope. In fact, that's exactly what Fellow David Nesbitt's group recently accomplished. Oliver Monti, a former JILA postdoc currently at the University of Arizona, graduate student Tom Baker, and Nesbitt have invented a microscope capable of analyzing the...
Running Backwards
Published: 10-02-2006
Does the electron have an electric dipole moment (eEDM)? If it does, the standard model of elementary particle physics says this dipole moment is many orders of magnitude below what can be measured experimentally. As Fellow John Bohn quips, "It's a darn small one." On the other hand, various extensions of the standard model predict a much larger eEDM that might be just within reach of a cleverly designed experiment. That tantalizing idea has induced Fellow Eric Cornell to collaborate with Bohn...
Team Photon
Published: 10-01-2006
When illuminated by X-ray and infrared light beams in tandem, electrons can tap dance off a platinum surface because they've actually grabbed a photon from both beams simultaneously. As you might have guessed, there is more going on here than the ordinary photoelectric effect, which Albert Einstein explained more than a century ago. In the photoelectric effect, electrons escape from a solid after absorbing a single photon or bundle of light energy. What happens when two laser beams...
Universal Attractions
Published: 10-01-2006
What do fermions in atomic nuclei, neutron stars, and ultracold trapped gases have in common? They have the same fundamental behavior. The exciting news is that there's now hard evidence that this is true, thanks to graduate students Jayson Stewart and John Gaebler, Cindy Regal who received her Ph.D. in physics in November, and Fellow Debbie Jin. Jin says that many of us might expect the behavior of an ultracold trapped gas of fermions to depend on the interactions between the fermions (or how...

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