Research Highlights

  • JILA Physicists Investigating Atomtronics
    February 01, 2007
    PI(s): Dana Anderson
    Topic(s): Atomic & Molecular Physics

    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.

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  • Imaging the Nanoworld
    October 29, 2006
    PI(s): David Nesbitt
    Topic(s): Nanoscience

    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.

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  • Running Backwards
    October 02, 2006
    PI(s): Eric Cornell, John Bohn
    Topic(s): Atomic & Molecular Physics

    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."

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  • Seeds of Creation
    October 01, 2006
    PI(s): Mitch Begelman
    Topic(s): Astrophysics

    There is an enormous black hole at the center of every galaxy, gobbling up matter over eons of time - some for as long as 13 billion years. One of the great questions of modern astronomy is: Where did the seeds for all these black holes come from? Not, as you might think, from the fiery collapse of massive hot stars formed in the early Universe, says Fellow Mitch Begelman. That may well be how new, much smaller black holes are formed, even now. However, despite long-standing theories to the contrary, Begelman believes that ancient supernovae cannot account for the genesis of the black holes as massive as a million suns at the center of galaxies.

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  • BEC Pancakes
    September 30, 2006
    PI(s): John Bohn
    Topic(s): Atomic & Molecular Physics

    Pancakes of Bose-Einstein condensates (BECs) of polar molecules are repulsive and potentially unstable. However, the physics of these dipolar condensates is delicious, according to research associate Shai Ronen, graduate student Daniele Bortolotti, and Fellow John Bohn. The JILA theorists recently studied BECs with purely dipolar interactions in oblate (pancake) traps.

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  • Molecule Magic
    September 30, 2006
    PI(s): Carl Wieman
    Topic(s): Atomic & Molecular Physics

    Under ordinary circumstances, making new molecules can be simple and straightforward - just a matter of mixing together some highly reactive chemicals and letting nature take its course. However, when the reactants are a few millionths of a degree above absolute zero, the creation of new molecules requires the sophisticated tools of modern experimental physics. Using those tools, graduate student Scott Papp and Fellow Carl Wieman recently created the world's first ultracold diatomic molecules made from two different atoms.

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  • Universal Attractions
    September 29, 2006
    PI(s): Deborah Jin
    Topic(s): Atomic & Molecular Physics

    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.

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  • Team Photon
    September 29, 2006
    PI(s): Henry Kapteyn, Margaret Murnane
    Topic(s): Laser Physics

    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. 

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  • The South Broadway Shootout
    September 29, 2006
    PI(s): Jun Ye
    Topic(s): Laser Physics

    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.

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  • Planetary Shakeup
    September 09, 2006
    PI(s): Phil Armitage
    Topic(s): Astrophysics

    For astrophysicists working to discover the origins of stars and planets, a small clue can go a long way. They can't get a close look at distant stars and planets, so they only know the barest details about other planetary systems. One such detail is that some extra-solar planets revolve around their stars in elliptical orbits rather than the nearly circular orbits that are the norm in our solar system. 

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  • In Soot I Sleep
    August 26, 2006
    PI(s): Jeffrey Linsky
    Topic(s): Astrophysics

    Left to their own devices, deuterium atoms would attach themselves to cold specks of soot floating in interstellar gas clouds and remain there for eternity. In fact, deuterium has a great affinity for the buckyballs, bucky onions, bucky tubes, and other forms of carbon, such as polycyclic aromatic hydrocarbons, comprising soot. It readily replaces hydrogen in these molecules. Deuterium atoms bond to interstellar soot so tightly it takes an encounter with a hot star or supernova explosion to pry them loose.

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  • Bull's Eye!
    July 28, 2006
    PI(s): David Nesbitt
    Topic(s): Chemical Physics

    "Chemistry is a highly improbable science," says Graduate Student Mike Deskevich, who adds "It's good for life on Earth that things are so unreactive." For instance, if chemical reactions happened easily and often, oxygen in the air would cause clothing and other flammable materials to burst into flame. In addition to making life difficult, high probability chemistry would render theoretical chemical physics much less interesting. As it is, theorists spend months determining the particular molecular shapes, vibrations, and energy states that make the simplest chemical reactions possible.

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  • Wanted: Gravitational Waves
    July 25, 2006
    PI(s): Peter Bender
    Topic(s): Precision Measurement

    When will the Laser Interferometer Space Antenna (LISA) fly? Fellows Jim Faller and Peter Bender first proposed the basic concept behind LISA more than 25 years ago. The joint European Space Agency/NASA mission first scheduled a possible launch in 2012. The date has now slipped to 2017, with additional delays possible. Both agencies are grappling with limited budgets and conflicting priorities. In the United States, plans for a future manned spaceflight to Mars are competing for funding with basic science-oriented space programs like LISA.

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  • Spectral Shapes
    July 17, 2006
    PI(s): David Nesbitt
    Topic(s): Chemical Physics

    The breakdown of chlorofluorocarbons (CFCs) in the stratosphere has been implicated in the destruction of Earth's protective ozone layer. Consequently, scientists have undertaken studies to better understand the structure and behavior of highly reactive, but short-lived, free radicals produced during the breakdown process. The molecules, which contain either fluorine or chlorine, are an important source of atmospheric halogen atoms. Elucidating their 3D structure and dynamical behavior will help scientists better understand atmospheric chemistry as well as their fundamental molecular properties.

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  • Trapped!
    July 16, 2006
    PI(s): W. Carl Lineberger
    Topic(s): Chemical Physics

    A solvent is something that dissolves or disperses something else. It's the water in salt water, the alcohol in cough syrup, the lactates or ethers in inks. For many of us, solvents are the background music of the chemistry taking place all around us. But this isn't how Fellow Carl Lineberger and his colleagues in chemical physics think about solvents. Lineberger, Former Research Associate Vladimir Dribinski, Graduate Students Jack Barbera and Josh Martin, and student visitor Annette Svendsen see them as key players in some chemical reactions, right down to the level of quantum mechanical interactions.

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  • Magic Light
    July 11, 2006
    PI(s): Jun Ye
    Topic(s): Laser Physics

    "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.

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  • Gold Fever
    July 07, 2006
    PI(s): Thomas Perkins
    Topic(s): Biophysics, Nanoscience

    Life can be challenging on the biophysics research frontier. Consider gold nanoparticles as a research tool, for example. Gold is ductile and malleable as well as being a good conductor of heat and electricity. Its unique chemistry allows proteins and DNA to be easily attached to these nanoparticles. Physicists have been investigating gold nanoparticles in optical-trapping experiments because they enhance trapping efficiency and potentially increase detection sensitivity.

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  • Constant Vigilance
    July 03, 2006
    PI(s): Heather Lewandowski
    Topic(s): Atomic & Molecular Physics, Nanoscience

    The fine structure constant is getting a lot of attention these days. Known as α, it is the "coupling constant," or measure of the strength of the electromagnetic force that governs how electrons, muons, and light interact. What's intriguing is that new models for the basic structure of matter predict that α may have changed over vast spans of cosmic time, with the largest variations occurring in the early universe. However, the Standard Model says a has always been the same. Our basic understanding of physics depends on scientists' ability to determine whether or not α is an "inconstant constant."

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  • Partnership in Time
    June 17, 2006
    PI(s): Jun Ye
    Topic(s): Atomic & Molecular Physics

    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.

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  • Bubbling Clusters of Galaxies
    June 10, 2006
    PI(s): Mitch Begelman
    Topic(s): Astrophysics

    Galaxy clusters contain enormous clouds of gas whose cooling should result in the formation of a multitude of new stars. But that's not what NASA's Chandra X-ray Observatory is detecting. Instead there's a whole lot less gas cooling and new star formation than scientists had predicted. Perhaps the most mysterious discovery of all is that the clusters are humming – a low B-flat 57 octaves below middle C. The hum originates from ripples of sound waves washing through great galactic gas clouds surrounding supermassive black holes.

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  • Flashdance!
    June 07, 2006
    PI(s): Chris Greene
    Topic(s): Atomic & Molecular Physics

    Imagine trying to describe the intricate motions of a single atom as it interacts with a laser. Then suppose you could generalize this understanding to a whole cloud of similar atoms and predict the temperatures your experimental physicist colleagues could achieve with laser cooling. This way-cool theoretical analysis comes compliments of Graduate Student Josh Dunn and Fellow Chris Greene.

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  • As the Sun Turns
    June 05, 2006
    PI(s): Juri Toomre
    Topic(s): Astrophysics

    Juri Toomre and his group concentrate their stellar research close to home--just 93 million miles away, to be precise. They want to answer the question: What dynamic processes occur deep within the Sun? To find out, they use a powerful combination of computer simulations and helioseismology (which analyzes sound waves produced by the Sun to probe its internal structure.) The researchers believe that working out the details of the Sun's internal structure should lead to explanations for the 22-year sunspot cycle and other regular surface features such as the Sun's consistent, but variable, rotation rate.

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  • Heme Motions
    May 17, 2006
    PI(s): Ralph Jimenez
    Topic(s): Biophysics, Chemical Physics

    Our lives depend on heme. As part of hemoglobin, it carries oxygen to our tissues. As part of cytochrome c, it helps transform the energy in food into the energy-rich molecule ATP (adenosine triphosphate) that powers biochemical reactions that keep us alive and moving. As part of cytochrome P450, it helps break down toxic chemicals in our bodies.

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  • Molecular Fingerprinting
    April 26, 2006
    PI(s): Jun Ye
    Topic(s): Laser Physics

    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.

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  • Flare Up!
    April 11, 2006
    PI(s): Phil Armitage, Rosalba Perna
    Topic(s): Astrophysics

    Gamma-ray bursts signal the birth of a new black hole, whether it's created during the collapse of a massive star or via a merger between two compact objects such as neutron stars. Astrophysicists have determined that long gamma-ray bursts are associated with collapsing stars and short bursts are associated with binary mergers. In both cases, however, black-hole accretion powers the burst. 

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  • Bubble Shock Trains
    April 10, 2006
    PI(s): Mitch Begelman
    Topic(s): Astrophysics

    Black holes are pretty strange, sucking in not only nearby matter but also the space around it. These cosmic vacuum cleaners are powered by thin, gaseous accretion disks in orbit around them. Something drives the orbiting gas to spiral in toward the black hole, where all trace of it disappears forever into the singularity. One of the exciting challenges in astrophysics is to figure out the physics driving this process, which keeps black holes growing for billions of years after they're formed.

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  • Body of Evidence
    April 10, 2006
    PI(s): Chris Greene
    Topic(s): Atomic & Molecular Physics

    One fun thing theorists do is undertake creative projects that predict phenomena that haven't yet been observed experimentally. In fact, sometimes they even predict things no one has ever imagined before. In other cases, the goal is to unravel the mechanism behind an experimental result that initially seems to conflict with the known laws of quantum physics. Fellow Chris Greene's group enjoys self-driven, innovative work in both categories.

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  • Charting the Fermi Sea
    April 03, 2006
    PI(s): Deborah Jin
    Topic(s): Atomic & Molecular Physics, Nanoscience

    JILA physicists are collaborating to explore the link between superconductivity and Bose-Einstein condensation (BEC) of fermions at ultracold temperatures. Fermions have an odd number of total protons, neutrons, and electrons, giving them a half integer spin, which is either up or down. At ultracold temperatures, this means fermions can't just occupy the same energy level (like bosons, which have an even number of atomic constituents) and form one superatom in a BEC. Instead, they stack up in the lowest energy states, with two fermions in each state, one spin up and one spin down, forming a Fermi sea.

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  • Cracking the Collision Code
    February 25, 2006
    PI(s): John Bohn
    Topic(s): Atomic & Molecular Physics

    When molecules smash into each other, things happen on the quantum level. Electrons get shoved around. They may even jump from one atom to another. Spin directions can change. A chemical reaction may even take place. Since it's not possible to directly observe this kind of electron behavior, scientists want to be able to probe it with novel spectroscopies. Now, thanks to a recent theoretical study, ultracold spectroscopy looks particularly promising for elucidating electron behavior during molecular impacts.

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  • Cool Star Winds
    February 19, 2006
    PI(s): Jeffrey Linsky
    Topic(s): Astrophysics

    We know a lot about cool stars because our Sun is one of them. However, we can't know for sure if cool stars produce winds (like the Sun does) without looking for evidence of such winds. Where stellar winds exist, they interact with hydrogen in the interstellar medium far from the star to produce tell-tale absorption in stellar ultraviolet spectral lines. 

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  • Designer Rings
    February 11, 2006
    PI(s): W. Carl Lineberger
    Topic(s): Chemical Physics

    One way to understand unstable molecules is to systematically create slightly different versions of a similar stable molecule and investigate each new molecule with identical analysis and experiments. That is exactly what researchers from JILA and CU are doing with a series of ringed molecules.

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  • The Tie That Binds
    February 11, 2006
    PI(s): Carl Wieman
    Topic(s): Atomic & Molecular Physics

    Graduate Student Sarah Thompson, Research Associate Eleanor Hodby, and Fellow Carl Wieman have come up with a novel way to assemble Feshbach molecules from a cloud of ultracold atoms. The molecules consist of very weakly bound atoms that are about as far apart in the molecular state as they are in the atom cloud from which they are formed. Understanding the properties of these molecules promises to help researchers better understand Bose-Einstein condensation and ultracold fermionic systems.

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  • Smudging Genetic Blueprints
    February 10, 2006
    PI(s): Chris Greene
    Topic(s): Chemical Physics

    High-energy radiation is notorious for damaging DNA, primarily by breaking chemical bonds. Damage to DNA can cause mutations, cancer, or even death. Much of this damage is inflicted by secondary, or low-energy, electrons knocked out of atoms in the DNA molecules by radiation. The low-energy electrons get captured by the DNA bases (which make up the letters of the genetic code), temporarily forming a negatively charged molecule (anion). The anion lasts just long enough to transfer its excess energy to the weakest nearby chemical bond, often breaking it.

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  • Spinning Out Stars & Planets
    February 10, 2006
    PI(s): Phil Armitage
    Topic(s): Astrophysics

    Scientists believe that planetary systems coalesce from disks of gas and dust orbiting a star. Similarly, stars can form within massive accretion disks orbiting a black hole. Determining the mechanisms that create stars and planets from these orbiting disks is a hot topic among astrophysicists, according to JILA Fellow Phil Armitage and colleagues W. K. M. Rice of the University of California, Riverside, and G. Lodato of Cambridge's Institute of Astronomy.

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  • Timely Comparisons
    February 10, 2006
    PI(s): Judah Levine
    Topic(s): Precision Measurement

    When Albert Einstein said, "the only reason for time is so that everything doesn't happen at once," he didn't know about studies performed by Senior Research Associate Christine Hackman and Fellow Judah Levine. These time-and-frequency experts work quite hard to devise ways of comparing the accuracy and stability of the world's premier atomic clocks - so that things like satellite communications and high-tech navigation can happen precisely when they're supposed to, including all at once.

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  • Molecular Secrets Revealed
    February 09, 2006
    PI(s): David Nesbitt
    Topic(s): Biophysics, Chemical Physics, Nanoscience

    Chemical physicists investigate the structure and behavior of atoms and molecules on the quantum level. Such research is particularly challenging when the molecule under investigation appears in small amounts and is rapidly transformed into something else, e.g., during combustion, chemical synthesis, or atmospheric chemical reactions. Happily, Research Associate Feng Dong, Fellow David Nesbitt, and former JILAn Scott Davis (now with Vescent Photonics in Denver) have developed an innovative method for studying such elusive chemicals.

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  • Atoms in Collision
    November 14, 2005
    PI(s): Steven Cundiff
    Topic(s): Laser Physics, Nanoscience

    "Watch" atoms collide! Thrill to the twists and turns of potassium atom wave functions as the atoms come closer and closer to impact! "See" the atoms deform, then recover as they smash together and fly apart inside a dense atomic vapor! It's all in a day's work for Graduate Student Virginia (Gina) Lorenz and Fellow Steve Cundiff.

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  • Time Traveling
    October 02, 2005
    PI(s): Jun Ye
    Topic(s): Atomic & Molecular Physics

    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.

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  • Gone with the Wind
    October 02, 2005
    PI(s): Phil Armitage
    Topic(s): Astrophysics

    Giant gas planets don't often stay in orbit where they're formed. They often move closer to their star or, occasionally, further away. Seldom do they remain in almost circular orbits such as those of Jupiter and Saturn. In fact, all but one of the giant gas planets discovered around other stars are closer to their star than Jupiter is to the Sun. A fraction of these planets are even closer than Mercury!

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  • Illuminating the Cosmic Web
    October 01, 2005
    PI(s): Andrew Hamilton
    Topic(s): Astrophysics

    Understanding dark matter's role in the distribution of galaxies in the Universe is a central question in cosmology. Dark matter pervades the universe. Haloes of dark matter surround galaxies and galaxy clusters. Dark matter also forms filamentary structures that connect these haloes, forming a cosmic web, as illustrated on the right. Until recently, cosmologists tried to understand the distribution of galaxies with theoretical analyses using different-sized dark matter haloes containing zero, one, or more galaxies.

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  • Surfing the Cosmic Shock Wave
    October 01, 2005
    PI(s): Richard McCray
    Topic(s): Astrophysics

    For nearly 18 years, JILA Fellow Dick McCray has been studying the brightest supernova to light up Earth's night skies since the Renaissance. Known as 1987A because it appeared in the southern sky on February 23, 1987, the supernova occurred when a 10-million-year-old blue supergiant star exploded in the Large Magellanic Cloud, a galaxy located 160,000 light years from Earth.

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  • Measure the Force, Luke
    October 01, 2005
    PI(s): Eric Cornell
    Topic(s): Nanoscience, Precision Measurement

    Graduate students Dave Harber and John Obrecht, postdoc Jeff McGuirk, and Fellow Eric Cornell recently devised a clever way to use a Bose-Einstein condensate (BEC) inside a magnetic trap to probe the quantum behavior of free space. To do this, the researchers first created a BEC inside a magnetic trap, whose shape (where the condensate forms) resembles a cereal bowl. Then as shown in the diagram to the right, they moved the BEC in the bowl closer and closer to a glass surface until distortions in the shape of the bowl appeared.

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  • Sudden Death: Jets Defeat Stars
    October 01, 2005
    PI(s): Mitch Begelman
    Topic(s): Astrophysics

    Gamma-ray jets produced deep within massive stars can blow apart the star when they emerge, creating a supernova. The jets are very light and travel near the speed of light toward the star's surface. They are created by a complex interaction of a black hole, an accretion disk, and very strong magnetic fields that come into being when a massive star depletes its supply of hydrogen fuel and falls into itself.

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  • Splash!
    October 01, 2005
    PI(s): David Nesbitt
    Topic(s): Chemical Physics, Nanoscience

    Brad Perkins and his thesis advisor Fellow David Nesbitt recently decided to explore what happens when fast, cold carbon dioxide molecules collide with the surface of an oily liquid (perfluoropolyether). Of course, you can only do these sorts of things in a vacuum chamber, where there are virtually no other gas molecules in the air to get in the way! The vacuum chamber itself creates an additional challenge: working with liquids at very low pressures.

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  • Amazing Molecular Velcro
    September 30, 2005
    PI(s): David Nesbitt
    Topic(s): Biophysics, Chemical Physics, Nanoscience

    RNA molecules can perform amazing biological feats, including storing, transporting, and reading genetic blueprints as well as catalyzing chemical reactions inside living cells. To manage the latter feat, RNA molecules must rapidly fold into an exact three-dimensional (3D) shape. Understanding how RNA accomplishes this is a major scientific challenge. Former JILA postdoc Jose Hodak, Christopher Downey (doctoral candidate in Chemistry and Biochemistry), JILA graduate student Julie Fiore, Chemistry and Biochemistry Professor Arthur Pardi and Fellow David Nesbitt are meeting this challenge head on.

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  • The Great Mouse Race
    September 29, 2005
    PI(s): Konrad Lehnert
    Topic(s): Nanoscience, Precision Measurement

    The race is on! Two mice chase one another around a curvy, roughly elliptical white stripe. But, the goal can't be the finish line – because there isn't one. Rather, the contest seems to be: Which mouse will stay on track for the longest time before spinning out of control? Of the two, one clearly "wags its tail" less as its phototransistor eyes guide it along the reflective white strip. 

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  • The Quest for Stability
    August 10, 2005
    PI(s): John Hall, Jun Ye
    Topic(s): Laser Physics, Precision Measurement

    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.

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  • X-Ray Flashes Deciphered
    May 11, 2005
    PI(s): Rosalba Perna
    Topic(s): Astrophysics

    Rosalba Perna and colleagues Jonathan Granot of Stanford and Enrico Ramirez-Ruiz of Princeton's Institute for Advanced Study recently figured out the relationship between X-ray flashes, X-ray rich gamma-ray bursts, and gamma-ray bursts detected by different space-based observatories. X-ray flashes are transient astronomical X-ray sources that last from several seconds to a few minutes. T

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  • Sightseeing along a DNA Strand
    May 01, 2005
    PI(s): Thomas Perkins
    Topic(s): Biophysics, Nanoscience

    Lora Nugent-Glandorf and Tom Perkins have come up with an optical trap motion detector that can "see" protein motors moving one base at a time along a DNA helix. For some time scientists have been able to make optical traps that can track the movement of attached beads, but the method had a resolution of 1-2 nanometers, which was not sensitive enough to resolve .338 nm DNA base steps. The lack of resolution was mostly due to instrument drift.

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  • Black Holes: The Inside Story
    April 20, 2005
    PI(s): Andrew Hamilton
    Topic(s): Astrophysics

    What really happens inside black holes? Andrew Hamilton and Scott Pollack, a graduate student in the Physics Department, recently decided to investigate the answer to this question. In the process, they developed a model using realistic physics that they believe better describes the internal structure of black holes.

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  • Space: Like a River
    April 10, 2005
    PI(s): Andrew Hamilton
    Topic(s): Astrophysics

    Andrew Hamilton and Jason Lisle, who received his Ph.D. in astrophysical and planetary sciences in 2004, have proposed a new model for the flow of matter into stationary and rotating black holes. In their "river model of black holes," space flows like a river through a flat background, while objects (like light rays) that move through the river abide by the rules of special relativity. 

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  • The World's First UV Frequency Comb
    April 10, 2005
    PI(s): Jun Ye
    Topic(s): Laser Physics

    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.

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  • There's Strontium in the Clock
    April 03, 2005
    PI(s): Chris Greene, Jun Ye
    Topic(s): Atomic & Molecular Physics

    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.

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  • Physics Class Rocks!
    April 03, 2005
    PI(s): Carl Wieman
    Topic(s): Other

    Imagine high-school or college students so excited about physics they can hardly wait to get to class every day and learn more about how the world works. Fellow Carl Wieman recently offered cogent suggestions to new physics teachers on coming closer to this ideal. First, he recommended starting with research on how people learn physics and paying particular attention to the concept of "cognitive load." This concept, which posits that people can only process about seven ideas in short-term working memory, sets clear limits on how much information can be effectively introduced in a single lesson (or scientific talk).

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  • The Power of Mirrors
    April 03, 2005
    PI(s): Jun Ye
    Topic(s): Laser Physics, Precision Measurement

    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.

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  • Light Control
    March 31, 2005
    PI(s): Steven Cundiff
    Topic(s): Laser Physics, Precision Measurement

    Pete Roos, Tara Fortier, Xiaoqin Li, Ryan Smith, Jessica Pipis, and Steve Cundiff are using a phase-controlled mode-locked laser to control quantum processes in semiconductors. Semiconductors are capable of producing electrical currents from light (and vice-versa) and are the basis for a wide variety of optoelectronic devices, including photodiodes, light-emitting diodes, and solar cells.

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  • Laws of Attraction
    June 14, 2001
    PI(s): Chris Greene
    Topic(s): Atomic & Molecular Physics

    It’s been more than 40 years since Russian theoretical physicist Vitaly Efimov predicted a strange form of matter called the Efimov state in 1970. In these strange states, three atoms can stick together in an infinite number of new quantum states, even though any two of the atoms can’t even form a molecule.

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