News & Highlights

Research Highlights

The Most Stable Clock in the World
Published: 12-05-2012
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. This impressive result was obtained by lead graduate student Travis Nicholson, graduate students Mike Martin, Ben Bloom, Mike Bishof, and Sara Campbell, research associate Jason Williams, former senior...
The Entanglement Tango
Published: 12-05-2012
Most scientists think it is really hard to correlate, or entangle, the quantum spin states of many particles in an ultracold gas of fermions. Fermions are particles like electrons (and some atoms and molecules) whose quantum spin states prevent them from occupying the same lowest-energy state and forming a Bose-Einstein condensate. Entanglement means that two or more particles interact and retain a connection. Once particles are entangled, if something changes in one of them, all linked...
Everything's Cool with Atom
Published: 11-29-2012
The Regal group recently completed a nifty feat that had never been done before: The researchers grabbed onto a single trapped rubidium atom (87Rb) and placed it in its quantum ground state. This experiment has identified an important source of cold atoms that can be arbitrarily manipulated for investigations of quantum simulations and quantum logic gates in future high-speed computers. Here’s how graduate students Adam Kaufman and Brian Lester and Fellow Cindy Regal did it: First, the...
Scratching the Surface
Published: 10-08-2012
Members of the Jin group found a way to measure for the first time the a type of abstract “surface” in a gas of ultracold atoms that had been predicted in 1926 but not previously observed. Jin and her colleagues are leading researchers in the field of ultracold Fermi gases made up of thousands to millions of fermions. Fermions, including electrons and some types of atoms such as potassium (40K), cannot occupy exactly the same quantum state. This property leads to a unique distribution of...
New Silicon Cavity Silences Laser Noise
Published: 09-12-2012
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. Interferometers are widely used measurement tools in optical atomic clocks, astronomy, and spectroscopy. Their thermal noise is due to...
New Flavors of Quantum Magnetism
Published: 05-24-2012
News Flash!  The Rey group has discovered another good reason for using alkaline-earth atoms, such as strontium (Sr) or Ytterbium (Yb), in experimental quantum simulators. Quantum simulators are systems that mimic interesting materials or mathematical models in a very controlled way. The new reason for using alkaline earth atoms in such systems comes from the fact that their nuclei come in as many as 10 different magnetic flavors, i.e., their spins can be in 10 different quantum states. When...
The Laser with Perfect Pitch
Published: 04-04-2012
The Thompson group, with theory help from the Holland group, recently demonstrated a superradiant laser that escapes the “echo chamber” problem that limits the best lasers. To understand this problem, imagine an opera singer practicing in an echo chamber. The singer hears his own voice echo from the walls of the room. He constantly adjusts his pitch to match that of his echo from some time before. But, if the walls of the room vibrate, then the singer’s echo will be shifted in pitch after...
The Secret Life of Magnets
Published: 03-15-2012
The Kapteyn/Murnane group and scientists from NIST Boulder and Germany have figured out how the interaction of an ultrafast laser with a metal alloy of iron and nickel destroys the metal’s magnetism. In a recent experiment, the researchers were able to observe how individual bits of quantum mechanical magnetization known as “spin” behaved after the metal was heated with the laser. The researchers included newly minted Ph. D. Chan La-o-vorakiat, former research associates Stefan Mathias and...
The Quantum Drum Song
Published: 02-23-2012
Fellows Konrad Lehnert and Cindy Regal are collaborating on an ambitious undertaking to explore the quantum behavior of tiny mechanical systems that are large enough to be visible to the naked eye (as opposed to systems exhibiting quantum behavior that are no bigger than a few tens of atoms). At the same time, they have been looking for ways to prolong vibrations in mechanical objects such as drums or strings. Prolonging vibrations makes it possible to laser cool objects to temperatures where...
Variation on an Infinity of Triangles
Published: 02-21-2012
The Greene group has just discovered some weird quantum states of ultracold fermions that are also dipoles. Dipoles are particles with small positively and negatively charged ends. Atoms (or molecules) that are fermions cannot occupy the same quantum state — unlike the neighborly bosons that readily occupy the same state and form Bose-Einstein condensates at ultracold temperatures. The new theoretical study was interesting because it explored what would happen to dipolar fermions under the...
The Indomitable Ruler of Light
Published: 02-02-2012
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...
No free lunch for entangled particles
Published: 01-26-2012
Incredibly sensitive measurements can be made using particles that are correlated in a special way (called entanglement.)  Entanglement is one of the spooky properties of quantum mechanics – two particles interact and retain a connection, even if separated by huge distances.  If you do something to one of the particles, its linked partners will also respond. However, entangled quantum states are notoriously fragile.  This fragility is an inherent part of their nature. Even so, a recent...
Schrödinger Cats Light the Way
Published: 01-13-2012
We can get valuable information about a material by studying how it responds to light.  But up to now, researchers have been forced to ignore how some of light’s stranger quantum behavior, such as being in a superposition of one or more intensity states, affects these measurements.  New research from the Cundiff group (with newly minted PhD Ryan Smith and graduate student Andy Hunter) has shown that it is possible to back-calculate how a semiconductor responds to light’s quantum features even...
Quantum Body Swapping
Published: 10-28-2011
There's something happenin’ here, what it is ain’t exactly clear -- Buffalo Springfield Theorists Norio Takemoto (now at the Weizmann Institute of Science) and Fellow Andreas Becker figured that something was amiss when they first analyzed the details of what occurs when an ultrafast laser dislodges an electron from a “simple” molecular ion, H2+. Since H2+ has already lost one of its electrons, its two protons only have one electron left to play with.  How hard would it be to “see” what...
Cross-Cultural Spectroscopy
Published: 10-19-2011
Graduate student Jennifer Lubbeck (Jimenez Group) spent the summer of 2011 doing research in the Molecular Spectroscopy Laboratory at the RIKEN Institute in Wako, Japan (near Tokyo). Her host's group included 16 postdocs and four graduate students (Figure 1). The group was under the direction of Chief Scientist Tahei Tahara. However, Lubbeck actually worked directly with just five other young scientists under the supervision of Professor Kunihiko Ishi (Ishi-san). “I was able to learn ultrafast...
Chemistry in the Cosmos
Published: 10-19-2011
Searching for Clues in Quantum Fingerprints The Nesbitt group wants to figure out how chemistry works in outer space. In particular, the group wants to understand the “cosmo”-chemistry leading to the generation of soot, which is similar to products of combustion here on Earth. “Outer space is full of molecules,” Nesbitt explains. “We want to discover how these molecules are formed out there.” He adds that radio telescopes have gathered evidence of molecules made of long chains of carbon atoms....
Ultracold Polar Molecules to the Rescue!
Published: 09-14-2011
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. There is already a...
The Cold Case
Published: 09-02-2011
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). Now...
Probing the Tell-Tale Ions
Published: 08-25-2011
JILA’s quest to determine whether the electron has an electric dipole moment (eEDM) began in 2006 with a suggestion by Fellow Eric Cornell that the molecular ion hafnium fluoride (HfF+) might be well suited for an eEDM experiment. An electric dipole moment is a measure of the separation of positive and negative charges in a system. If an electron does have an electric dipole moment, it’s a pretty darn small one. So small, in fact, that if the electron were the size of the Earth, its eEDM would...
Reactions on Demand
Published: 07-16-2011
Predrag Ranitovic dreams of controlling chemical reactions with ultrafast lasers. Now he and his colleagues in the Kapteyn/Murnane group are one step closer to bringing this dream into reality. The group recently used a femtosecond infrared (IR) laser and two extreme ultraviolet (XUV) harmonics created by the same laser to either ionize helium atoms or prevent ionization, depending on experimental conditions. The researchers adjusted experimental conditions to manipulate the electronic...
The Secrets of the Resonant Lattice
Published: 07-15-2011
Theoretical physicists recently combined two powerful tools for exploring ultracold atomic gases: Optical lattices and Feshbach resonances. Optical lattices are crystals of light formed by interacting laser beams. Feshbach resonances in an ultracold atom gas occur at a particular magnetic field strength and cause ultracold atoms to form very large, loosely associated molecules. However, because lattice atoms interact strongly at a Feshbach resonance, the physics of Feshbach resonances in an...
Laws of Attraction
Published: 06-14-2011
There’s exciting news in the field of Efimov 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. For a long time, scientists were skeptical about Efimov’s prediction. However, since the 1990s, Fellow Chris Greene’s group (with J. P....
Quantum CT Scans
Published: 06-01-2011
The Lehnert group and collaborators from the National Institute of Standards and Technology (NIST) recently made what was essentially a CT scan of the quantum state of a microwave field. The researchers made 100 measurements at different angles of this quantum state as it was wiggling around. Because they only viewed the quantum state from one angle at a time, they were able to circumvent quantum uncertainties to make virtually noiseless measurements of amplitude changes in their tiny microwave...
JILA MONSTR and the Chamber of Secrets
Published: 05-17-2011
The semiconductor gallium arsenide (GaAs) is used to make tiny structures in electronic devices such as integrated circuits, light-emitting diodes, laser diodes, and solar cells that directly convert light into electrical energy. Because of GaAs’s importance to modern electronics, the Cundiff group seeks to understand the fundamental physics of its light-matter interactions on atomic and electronic levels. Such an understanding requires the ability to “look” inside tiny boxes of GaAs (called...
I Sing the Body Electric
Published: 05-11-2011
The Lewandowski group recently decided to see what would happen if it could get cold molecules (1K–1mK) and ultracold (3) molecules and ultracold (600 microK) rubidium (Rb) atoms. The researchers hoped their experiment would help elucidate the role of quantum mechanics in molecular collisions. Their novel experimental setup is shown in the top picture (Figure 1). The researchers cool and trap Rb atoms at the intersection of the (red) laser-cooling beams. Then a pulsed valve (lower right)...

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