News & Highlights

Research Highlights

Metamorphosis
Published: 07-01-2015
A grand challenge of ultracold physics is figuring out how fermions become bosons. This is an important question because the tiniest quantum particles of matter are all fermions. However, these fermions can form larger chunks of matter, such as atoms and molecules, which can be either fermions or bosons. An interesting feature of fermions and bosons is that they behave very differently at ultracold temperatures. Fermions prefer to go it alone while bosons tend to hang out together. To learn...
About Time
Published: 04-21-2015
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...
A Bug’s Life
Published: 04-20-2015
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. At...
An Ultrafast Photoelectric Adventure
Published: 03-02-2015
The photoelectric effect has been well known since the publication of Albert Einstein’s 1905 paper explaining that quantized particles of light can stimulate the emission of electrons from materials. The nature of this quantum mechanical effect is closely related to the question how much time it might take for an electron to leave a material such as a helium atom. The exciting news at JILA is that the Ultrafast AMO Theory Group has come up with a clever way that may help to answer this question...
Terms of Entanglement
Published: 02-27-2015
When the Rey theory group first modeled a quantum system at JILA, it investigated the interactions of strontium atoms in the Ye group’s strontium-lattice clock. The quantum behavior of these collective interactions was relatively simple to model. However, the group has now successfully tackled some more complicated systems, including the ultracold polar KRb molecule experiment run by the Jin and Ye groups. In the process, the group has developed a new theory that will open the door to probing...
Mutant Chronicles
Published: 01-20-2015
Because red fluorescent proteins are important tools for cellular imaging, the Jimenez group is working to improve them to further biophysics research. The group’s quest for a better red-fluorescent protein began with a computer simulation of a protein called mCherry that fluoresces red light after laser illumination. The simulation identified a floppy (i.e., less stable) portion of the protein “barrel” enclosing the red-light emitting compound, or chromophore. The thought was that when the...
The Polarized eXpress
Published: 12-10-2014
Until recently, researchers who wanted to understand how magnetic materials work had to reserve time on a large, stadium-sized X-ray machine called a synchrotron. Synchrotrons can produce X-ray beams that can be sculpted very precisely to capture how the spins in magnetic materials work together to give us beautiful and useful magnetic properties – for example to store data in a computer hard drive. But now, thanks to Patrik Grychtol and his colleagues in the Kapteyn/Murnane group, there’s a...
Exciting Adventures in Coupling
Published: 10-31-2014
New theory describing the spin behavior of ultracold polar molecules is opening the door to explorations of exciting, new physics in JILA’s cold molecular lab, operated by the Jin and Ye groups. According to the Rey theory group and its collaborators, ultracold dipolar molecules can do even more interesting things than swapping spins. For instance, spin swapping occurs naturally when ultracold potassium-rubidium (KRb) molecules are in two of their four possible excited and ground states. The...
The Quantum Identity Crisis
Published: 10-14-2014
Dynamical phase transitions in the quantum world are wildly noisy and chaotic. They don’t look anything like the phase transitions we observe in our everyday world. In Colorado, we see phase transitions caused by temperature changes all the time: snow banks melting in the spring, water boiling on the stove, slick spots on the sidewalk after the first freeze. Quantum phase transitions happen, too, but not because of temperature changes. Instead, they occur as a kind of quantum “metamorphosis”...
Atoms, Atoms, Frozen Tight in the Crystals of the Light, What Immortal Hand or Eye Could Frame Thy Fearful Symmetry?
Published: 08-18-2014
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). This first-...
Quantum Entanglement
Published: 07-13-2014
The spooky quantum property of entanglement is set to become a powerful tool in precision measurement, thanks to researchers in the Thompson group. Entanglement means that the quantum states of something physical—two atoms, two hundred atoms, or two million atoms—interact and retain a connection, even over long distances. Even without exploiting entanglement, atoms are already used as exquisite sensors of time, gravity, rotations, and magnetic fields because the rules of quantum mechanics allow...
Invisible Rulers of Light
Published: 06-20-2014
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...
Sky Clocks and the World of Tomorrow
Published: 06-13-2014
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...
The Long and the Short of Soft X-rays
Published: 05-27-2014
Mid-infrared (mid-IR) laser light is accomplishing some remarkable things at JILA. This relatively long-wavelength light (2–4 µm), when used to drive a process called high-harmonic generation, can produce bright beams of soft x-rays with all their punch packed into isolated ultrashort bursts. And, all this takes place in a tabletop-size apparatus. The soft x-rays bursts have pulse durations measured in tens to hundreds of attoseconds (10-18 s). Until now, attosecond pulses were limited to the...
Crowd-Folding
Published: 05-22-2014
Biomolecules may not always behave the same way in test tubes as they do in living cells, a fact underscored by important new work by former research associate Nick Dupuis, graduate student Erik Holmstrom, and Fellow David Nesbitt. The researchers found that under crowded conditions that begin to mimic those found in cells, single RNA molecules folded 35 times faster than in the dilute solutions typically used in test-tube experiments. Crowding also led to a modest decrease in the unfolding...
The Measure of Small Things
Published: 04-23-2014
Fellow Tom Perkins’ group is significantly closer to realizing its long-standing dream of using atomic force microscopy (AFM) to study how membrane proteins fold and unfold. Historically, scientists have used AFM to measure the mechanical forces needed to unfold individual proteins and the resulting increase in their lengths. However, the limitations of AFM itself have prevented researchers from watching the unfolding process in detail. For AFM to resolve protein unfolding in detail, three...
The Unfolding Story of Telomerase
Published: 04-17-2014
Graduate student Erik Holmstrom and Fellow David Nesbitt have applied their laboratory research on the rates of RNA folding and unfolding to the medically important enzyme telomerase. Telomerase employs both protein and RNA components to lengthen chromosomes, which are shortened every time they are copied. If one short piece of the RNA in telomerase is folded into an organized structure called a pseudoknot, then the enzyme works properly. The enzyme repeatedly adds short pieces of DNA to the...
Good Vibrations: The Experiment
Published: 03-19-2014
The Regal-Lehnert collaboration has just taken a significant step towards the goal of one day building a quantum information network. Large-scale fiber-optic networks capable of preserving fragile quantum states (which encode information) will be necessary to realize the benefits of superfast quantum computing. Such networks will require new technology to reversibly convert low-frequency microwave light (i.e., electrical signals) to high-frequency infrared or visible light, without losing any...
Dealing with Loss
Published: 03-05-2014
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. That it works this way is a consequence of the quantum Zeno effect, also known as the watched pot...
Fog Island
Published: 02-26-2014
When Andy Almand-Hunter and his colleagues in the Cundiff group shined a laser on a sample of gallium arsenide (GaAs), the last thing they were expecting to create was a fog of liquid-like quantum droplets, which the group named "dropletons." Dropletons are a new, stable form of matter much like an ordinary liquid—with one key difference. Unlike normal everyday liquids, quantum droplets contain charged particles. The particles are negatively charged electrons and positively charged “holes.”...
bR Phone Home
Published: 02-04-2014
The groups of Fellow Adjoint Markus Raschke and Fellow Tom Perkins joined forces recently to shine light onto a bacterial membrane protein called bacteriorhodopsin (bR). They used a new infrared (IR) light imaging system with a spatial resolution and chemical sensitivity of just a few bR molecules. In their experiment, the tip of an atomic force microscope (AFM) acted like an antenna for the IR light, focusing it onto the sample. The AFM-tip antenna then helped capture the signal emitted by the...
A Clockwork Blue Takes the Gold
Published: 01-22-2014
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. JILA Fellow Jun Ye’s group has developed an optical atomic clock that uses neutral Sr atoms held in an optical lattice (i.e., crystal of light) to generate the ticks of its clock. The Sr-lattice clock can precisely control the quantum states of...
Mission: Control
Published: 01-14-2014
Capturing and controlling the fleeting dance of electrons as they rearrange during a chemical reaction has been a long-standing challenge in science for several decades. Since electrons are much lighter than atoms, they can respond almost instantaneously – on time scales of hundreds of attoseconds, where an attosecond is 10-18 s. Fortunately, over the last decade scientists have created attosecond x-ray strobe lights that are fast enough to freeze the motion of electrons. However, simply...
Puff the Magic Atoms
Published: 01-13-2014
The Cornell and Jin groups have just met the challenge of creating and studying an extremely strongly interacting Bose-Einstein condensate (BEC). This feat was reported in Nature Physics online January 12, 2014. An example of an ordinary weakly interacting Bose-Einstein condensate (BEC) is a quantum gas of rubidium atoms (85Rb) all piled up in a little ball whose temperature is a chilly 10 nK. Normally, the interactions between these atoms are weak, and the atoms behave as if they were much...
The Dipolar Express
Published: 12-06-2013
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...

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