News & Highlights

Research Highlights

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Published: 04-14-2009
Starting with ultracold atoms in a Bose-Einstein condensate, it’s possible to create coherent superpositions of atoms and molecules. Fellow Carl Wieman and others have done exactly this. Recently, the Jin group wondered if it would be possible to accomplish the same thing starting with a normal gas cloud of atoms. To spice up the experiment, they included two kinds of atoms: neighborly bosons (87Rb) that readily pile up in the same state and more independent-minded fermions (40K), no two of...
Altered States
Published: 04-12-2009
Understanding how molecules collide is a hot topic in ultracold physics. Knowing the number of times molecules crash into each other and what happens when they do helps theorists predict the best ways to cool molecules to merely cold (1 K–1 mK), pretty cold (1 mK–1 µk), or ultracold ( Fellow John Bohn recently decided to investigate the general collision behavior of polar molecules in low-temperature gases. He wanted to see whether knowing the molecule’s dipole moment and mass would be...
It Takes Two to Tango
Published: 04-12-2009
Quantum dots are tiny structures made of semiconductor materials. With diameters of 1–5 nm, they are small enough to constrain their constituents in all three dimensions. This constraint means that when a photon of light knocks an electron into the conduction band and creates an electron/hole pair, the pair can’t get out of the dot. In terms of quantum mechanics, this confinement means that the wavelengths of the wave functions of both the electron and the hole are forced to be significantly...
How to Marry a Microscope
Published: 04-10-2009
The most important step for a microscope wanting to marry another microscope is finding the right partner. A professional matchmaker, such as the Perkins lab, might be just the ticket. The group recently presided over the nuptials of atomic force microscopy and optical-trapping microscopy. Research associate Gavin King, graduate students Ashley Carter and Allison Churnside, CU freshman Louisa Eberle, and Fellow Tom Perkins officiated. The marriage produced an ultrastable atomic force...
Fermions in Collision?
Published: 04-07-2009
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. They (along with every other physicist in the world) assumed that using...
Collision Course
Published: 04-05-2009
The Greene group just figured out everything you theoretically might want to know about four fermions "crashing" into each other at low energies. Low energies in this context mean ultracold temperatures under conditions where large, floppy Feshbach molecules form. The group decided to investigate four fermions because this number makes up the smallest ultracold few-body system exhibiting behaviors characteristic of the transition between Bose-Einstein condensation and superfluidity. Senior...
Qubits in Action
Published: 04-05-2009
Fellows Ana Maria Rey and Jun Ye have come up with a clever idea that should make it much easier to design a quantum computer based on alkaline-earth atoms such as strontium (Sr). In this work, they collaborated with former research associate Marty Boyd, former JILA Fellow Peter Zoller (University of Innsbruck), and colleagues from Harvard University and the University of Innsbruck. To understand the new quantum computing idea, it’s helpful to imagine a high-tech company as a quantum...
Explosive Evidence
Published: 02-27-2009
Imagine being able to study how molecules form on the quantum level. It turns out that researchers have already figured out some nifty techniques involving lasers and jets of reactive atoms for doing just that in a gaseous environment. Now graduate student Alex Zolot, former Visiting Fellow Paul Dagdikian of Johns Hopkins University, and Fellow David Nesbitt have taken this kind of study into a whole different arena: They recently probed the molecules that form when the surface of a liquid is...
Beams In Collision
Published: 02-20-2009
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...
Breaking Up Is Hard To Do
Published: 02-13-2009
An oxygen molecule (O2) doesn't fall apart so easily — even when an X-ray knocks out one of its electrons and superexcites the molecule during a process called photoionization. In this process, the X-ray first removes an electron from deep inside the molecule, leaving a hole in O2+. Then, an outer electron can fall into the hole, and a second outer electron gets ejected, carrying away any excess energy. The loss of the second electron is known as autoionization, or Auger decay. Surprisingly, in...
Fortune’s Bubbles Rise and Fall
Published: 02-08-2009
A while back, former graduate student Scott Papp, graduate student Juan Pino, and Fellow Carl Wieman decided to see what would happen as they changed the magnetic field around a mixture of two different rubidium (Rb) isotopes during Bose-Einstein condensation. They assumed that the interactions between the atoms would change. They also expected they would observe two distinct condensates at some point. What they didn’t expect was the formation of alternating "bubbles" of 85Rb and 87Rb inside...
Exotic Probes
Published: 10-13-2008
Xibin Zhou and his colleagues in the Kapteyn/Murnane group have come up with a clever new way to study the structure of carbon dioxide (CO2) and other molecules. The researchers use two innovative tools: (1) coherent electrons knocked out of the CO2 molecules by a laser and (2) the X-rays produced by these electrons when they recollide with the same molecules. The coherent electrons and X-rays are produced in a process known as high harmonic generation. The process involves four steps. First,...
The Oldest Trick in the Book
Published: 10-03-2008
The mission to find the electron electric dipole moment (eEDM) recently took a menacing turn. Chief Eric Cornell and his protégés were already hard at work characterizing the hafnium fluoride ion (HfF+). Their goal was to be the first in the world to complete the mission. In their choice of molecule, they owed a lot to JILA theorists Ed Meyer and John Bohn (a.k.a. Agents 13 and 86), who had taken the theory world by storm in 2006 when they devised a simple and straightforward method for the...
All Quiet on the Amplifier Front
Published: 10-01-2008
Fellow Konrad Lehnert needed a virtually noiseless amplifier to help with his experiments on nanoscale structures, so he invented one. Working with graduate student Manuel Castellanos-Beltran and NIST scientists Kent Irwin, Gene Hilton, and Leila Vale, he conceived a tunable device that operates in frequencies ranging from 4 to 8 GHz. This device has the lowest system noise ever measured for an amplifier. In fact, it produces 80 times less noise than the best commercial amplifier. More...
From Mental to Experimental?
Published: 07-16-2008
The John Bohn lab at JILA owes its very existence to a 2002 decision by the Colorado Rockies to begin storing baseballs in a room with ~50% humidity. The conventional wisdom at the time was that Denver’s thinner air was responsible for making Coors Field a hitter’s heaven. In mile-high Denver, hitters averaged two more home runs per game because the thinner air caused a given home run ball to travel 20 feet further than at sea level. The humidified baseballs were supposed to solve the problem...
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...

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