Research Highlights

The Kapteyn/Murnane group has measured how long it takes an electron born into an excited state inside a piece of nickel to escape from its birthplace. The electron’s escape is related to the structure of the metal. The escape is the fastest material process that has been measured before in the laboratory––on a time scale of a few hundred attoseconds, or 10^-18 s. This groundbreaking experiment was reported online in Scienceon June 2, 2016. Also in Science on July 1, 2016, Uwe Bovensiepen and Manuel Ligges offered important insights into the unusual significance of this work. 

The Ye group just solved a major problem for using molecular fingerprinting techniques to identify large, complex molecules: The researchers used an infrared (IR) frequency comb laser to identify four different large or complicated molecules. The IR laser-light absorption technique worked well for the first time with these larger molecules because the group combined it with buffer gas cooling, which precooled their samples to just a few degrees above absolute zero. 

Move over, single-atom laser cooling! The Holland theory group has just come up with a stunning idea for a new kind of laser cooling for use with ensembles of atoms that all “talk” to each other. In other words, the theory looks at laser cooling not from the perspective of cooling a single atom, but rather from the perspective of many atoms working together to rapidly cool themselves to a miniscule fraction of a degree above absolute zero.

The old JILA molecule factory (built in 2002) produced the world’s first ultracold polar molecules [potassium-rubidium (KRb)] in 2008. The old factory has been used since then for ultracold chemistry investigations and studies of the quantum behavior of ultracold molecules and the atoms that form them. The Jin-Ye group, which runs the molecule factory, is now wrapping up operations in the old factory with experiments designed to improve operations in the ultramodern factory, which is close to completion.

The Ye and Rey groups have discovered the strange rules of quantum baseball in which strontium (Sr) atoms are the players, and photons of light are the balls. The balls control the players by not only getting the atoms excited, but also working together. The players coordinate throwing and catching the balls. While this is going on, the balls can change the state of the players! Sometimes the balls even escape the quantum baseball game altogether and land on detectors in the laboratory.

Cong Chen and his colleagues in the Kapteyn/Murnane group have generated one of the most complex coherent light fields ever produced using attosecond (10-18 s) pulses of circularly polarized extreme ultraviolet (EUV) light. (The circularly polarized EUV light is shown as rotating blue sphere on the left of the picture. The complex coherent light field is illustrated with the teal, lilac, and purple structures along the driving laser beam (wide red line).

The Rey and Ye groups are in the midst of an extended collaboration on using the Ye group’s strontium (Sr) lattice clock for studies of spin-orbit coupling in pancake-like layers of cold Sr atoms. Spin-orbit coupling means an atom’s motion is correlated with its spin. It occurs in everyday materials when negatively charged electrons move in response to electromagnetic fields inside a crystal.

In 2008, Fellow Jeff Linsky and his colleague Seth Redfield of Wesleyan University used spectral information gathered by the Hubble Space Telescope to figure out that the solar system is surrounded by 15 nearby clouds of warm gas, all within 50 light years of the Sun. In 2014, Cécile Gry of Aix-Marseille Université (France) and Edward Jenkins of Princeton University Observatory analyzed the same data, but came up with a much simpler picture of the local interstellar medium, or LISM.

Imagine laser-like x-ray beams that can “see” through materials––all the way into the heart of atoms. Or, envision an exquisitely controlled four-dimensional x-ray microscope that can capture electron motions or watch chemical reactions as they happen. Such exquisite imaging may soon be possible with laser-like x-rays produced on a laboratory optical table. These possibilities have opened up because of new research from the Kapteyn/Murnane group.

In the future, quantum microwave networks may handle quantum information transfer via optical fibers or microwave cables. The evolution of a quantum microwave network will rely on innovative microwave circuits currently being developed and characterized by the Lehnert group. Applications for this innovative technology could one day include quantum computing, converters that transform microwave signals to optical light while preserving any encoded quantum information, and advanced quantum electronics devices.

JILA’s cold molecule collaboration (Jin and Ye Groups, with theory support from the Rey Group) recently made a breakthrough in its efforts to use ultracold polar molecules to study the complex physics of large numbers of interacting quantum particles. By closely packing the molecules into a 3D optical lattice (a sort of “crystal of light”), the team was able to create the first “highly degenerate” gas of ultracold molecules.

The Regal and Rey groups have come up with a novel way to generate and propagate quantum entanglement [1], a key feature required for quantum computing. Quantum computing requires that bits of information called qubits be moved from one location to another, be available to interact in prescribed ways, and then be isolated for storage or subsequent interactions. The group showed that single neutral atoms carried in tiny traps called optical tweezers may be a promising technology for the job!

Scientists often use ultracold atoms to study the behavior of atoms and electrons in solids and liquids (a.k.a. condensed matter). Their goal is to uncover microscopic quantum behavior of these condensed matter systems and develop a controlled environment to model materials with new and advanced functionality.

The Perkins Group has demonstrated a 50-to-100 times improvement in the time resolution for studying the details of protein folding and unfolding on a commercial Atomic Force Microscope (AFM). This enhanced real time probing of protein folding is revealing details in these complex processes never seen before. This substantial enhancement in AFM force spectroscopy may one day have powerful clinical applications, including in the development of drugs to treat disease caused by misfolded proteins. Misfolded proteins are implicated in such fatal maladies as Creutzfeldt–Jakob disease and mad cow disease, both of which are caused by prions.

Fellow Phil Armitage and his collaborator Jake Simon of the Southwest Research Institute recently conducted a theoretical study of turbulence in the outer reaches of an accretion disk around HD 163296, a nearby young star. Meanwhile, the Atacama large Millimeter/submillimeter Array (ALMA) in northern Chile observed the same accretion disk. There were intriguing and unexpected differences between what the theory predicted and what the observation revealed.

It took Eric Cornell three years to build JILA’s first Top Trap with his own two hands in the lab. The innovative trap relied primarily on magnetic fields and gravity to trap ultracold atoms. In 1995, Cornell and his colleagues used the Top Trap to make the world’s first Bose-Einstein condensate (BEC), an achievement that earned Cornell and Carl Wieman the Nobel Prize in 2001.

The Kapteyn/Murnane group, with Visiting Fellow Charles Durfee, has figured out how to use visible lasers to control x-ray light! The new method not only preserves the beautiful coherence of laser light, but also makes an array of perfect x-ray laser beams with controlled direction and polarization. Such pulses may soon be used for observing chemical reactions or investigating the electronic motions inside atoms. They are also well suited for studying magnetic materials and chiral molecules like proteins or DNA that come in left- and right-handed versions.

Graduate student Brian Lester of the Regal group has taken an important step toward building larger, more complex systems from single-atom building blocks. His accomplishment opens the door to advances in neutral-atom quantum computing, investigations of the interplay of spin and motion as well as the synthesis of novel single molecules from different atoms.

When an ordinary star like our Sun wanders very close to a supermassive black hole, it’s very bad news for the star. The immense gravitational pull of the black hole (i.e., tidal forces) overcomes the forces of gravity holding the star together and literally pulls the star apart. Over time, the black hole swallows half of the star stuff, while the other half escapes into the interstellar medium. This destructive encounter between a supermassive black hole and a star is known as a tidal disruption event.

Ever wondered how magnetic pressure alone might be able to maintain the structure of an accretion disk around a black hole in an x-ray binary system? Fellow Mitch Begelman recently gave the idea a lot of thought. And, in the process of working on the idea with Fellow Phil Armitage and Chris Reynolds of the University of Maryland, Begelman came up with a new model for accretion disks around black holes in x-ray binary systems, such as the one shown in the picture.