Research Highlights

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.

Compact and transportable optical lattices are coming soon to a laboratory near you, thanks to the Anderson group and its spin-off company, ColdQuanta. A new robust on-chip lattice system (which measures 2.3 cm on a side) is now commercially available. The chip comes with a miniature vacuum system, lasers, and mounting platform.

For astrophysicists like Fellow Jeff Linsky, the Lyman-α spectral line of atomic hydrogen is a powerful tool for investigating the stellar winds emitted by stars, the deuterium/hydrogen (D/H) ratio in the Galaxy, the excited states of hydrogen molecules and carbon monoxide in the environments around young stars, and photochemical processes that create oxygen in the atmospheres of planets around other stars, or exoplanets.

A wildly successful JILA (Nesbitt Group)-NIH collaboration is opening the door to studies of RNA behavior, including binding, folding and other factors that affect structural changes of RNA from living organisms. Such structural changes determine RNA enzymatic functions, including the regulation of genetic information.

For decades after the invention of the red ruby laser in 1960, bright laser-like beams were confined to the infrared, visible, and ultraviolet region of the spectrum. Today there’s an exciting revolution afoot: new coherent x-ray beams are now practical, including the EUV beams gracing the cover of the May 1, 2015, special issue of Science honoring the International Year of Light. The same issue features an article entitled “Beyond Crystallography: Diffractive Imaging Using Coherent X-ray Light Sources” that celebrates the revolutionary advances in both large- and small-scale coherent x-ray sources that are transforming imaging in the 21st century.

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 traditional applications for timekeeping such as navigation (GPS) and communications.

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.

One of the great challenges in the semiconductor and electronics industries is that as nanoscale features get smaller and processes get faster, enormous amounts of heat need to be quickly carried away from the nanostructures. The Kapteyn/Murnane group has made the counter-intuitive discovery that it is easier to cool these nanostructures when they are arranged closely together. The researchers also developed a theory to explain this unexpected new behavior.

Supermassive black holes at the center of active galaxies are known as blazars when they are extremely bright and produce powerful jets of matter and radiation visible along the line of sight to the Earth. Blazars can appear up to a thousand times more luminous than ordinary galaxies, and their associated jets are so powerful they can travel millions of light years across the Universe. Blazar jets produce flares of high-energy gamma rays that are detected by ground- and space-based observatories.

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.

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.

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 quantum spin behavior in real materials; atomic, molecular and optical gases; and other complex systems. The new theory promises important insights in different areas of physics, quantum information science, and biology.

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 barrel flopped open, it would allow oxygen in to degrade the chromophore, thus destroying its ability to fluoresce.