News & Highlights

Research Highlights

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)...
The Long Goodbye
Published: 04-01-2011
The dance of electrons as a bromine molecule (Br2) separates into two atoms is intricate and complex. The process of breaking up takes far longer than expected (~150 vs 85 fs) because the cloud of electrons that bind atoms together in a molecule behaves as if it were still surrounding a molecule until the last possible moment — when the atomic fragments are about twice the normal distance apart (~.55 nm). At this point, there’s simply not enough energy left in the system to hold the molecule...
The Quantum Control Room
Published: 03-21-2011
In 2008, the Ye and Jin groups succeeded in making ultracold potassium-rubidium (KRb) molecules in their ground state (See “Redefining Chemistry at JILA” in the Spring 2010 issue of JILA Light & Matter). Their next goal was to figure out how to precisely control chemical reactions of these ultracold polar molecules by manipulating the quantum states of the reactants. But first the researchers had to discover how to calm those reactions down enough to study them. Under the conditions in...
The Fickle Finger of Fate
Published: 02-24-2011
Putting the brakes on a superfluid dipolar Bose-Einstein condensate (BEC) just got a whole lot more interesting. Last year, the Bohn theory group explored what would occur in a dipolar BEC when a laser probe — think of it like a finger — tickled a BEC just hard enough to excite a roton. (see JILA Light & Matter, Summer 2010). The roton is a strange type of quasi particleformed when a number of strongly magnetic atoms or dipolar molecules come together and act like a different kind of...
Strontium Clock Performance Skyrockets
Published: 02-03-2011
Quantum Paradox Derails Unwanted Collisions In 2008-2009, much to their amazement,researchers working on the Jun Ye group’s neutral Sr optical atomic clock discovered tiny frequency shifts caused by colliding fermions! They figured out that the clock laser was interacting slightly differently with the Sr atoms inside a one-dimensional (pancake-shaped) trap. The light-atom interactions resulted in the atoms no longer being identical. And, once they were distinguishable, formerly unneighborly...
The Quantum Modeling Agency
Published: 01-14-2011
“Nature is built quantum mechanically,” says Fellow Jun Ye, who wants to understand the connections between atoms and molecules in complex systems such as liquids and solids (aka condensed matter). He says that the whole Universe is made of countless interacting particles, and it would be impossible to figure out the myriad connections between them one particle at a time, either theoretically or experimentally. Fortunately, in 1986 Richard Feynman envisioned a work-around for the challenge of...
Sharing the Adventure of Science
Published: 01-03-2011
Graduate students or research associates at JILA have the option of signing up to help teach after-school science classes to elementary and middle school students in the St. Vrain School District. The volunteers expect to stimulate the children to learn to think critically, enjoy science activities, and become confident in their own abilities to master difficult concepts. What they may not anticipate at first is that they will learn some important skills themselves, including the ability to...
Rainbows of Soft X-Rays
Published: 12-06-2010
The vision of a tabletop x-ray laser has taken a giant step into reality, thanks to Tenio Popmintchev, Ming-Chang Chen and their colleagues in the Kapteyn/Murnane group. By focusing a femtosecond laser into a gas, Popmintchev and Chen generated many colors of x-rays at once, in a band that stretched from the extreme ultraviolet into the soft x-ray region of the electromagnetic spectrum, spanning wavelengths of ranging from about 6 to 2.5 nm. This broad x-ray band has so many different colors...

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