Research Highlights

Quantum chaos just showed up in an ultracold gas of erbium atoms, and the Bohn theory group knows why. Theorists expect quantum chaos to appear when quantum mechanical objects get sufficiently complicated. But until now, scientists hadn’t realized that something as simple as a pair of colliding atoms could be complicated enough for quantum chaos to appear.

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.

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.

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.

Fellows Mitch Begelman and Phil Armitage have just solved the 40-year old mystery of what causes the gas of stellar debris surrounding black holes in binaries to flip back and forth cyclically between a spherical cloud and a luminous disk.

Black holes have a new item on their dinner menu: a three-dimensional glowing sphere of stellar debris that looks like a star. The sphere provides a sumptuous main course for a supermassive black hole, while emitting excess energy via jets erupting from its polar regions. The idea for this new type of gourmet feast for black holes comes compliments of graduate student Eric Coughlin and Fellow Mitch Begelman.

Real-world quantum mechanics may not always work exactly like the simple picture presented in textbooks, according to observations made by research associate Gaël Nardin and his colleagues in the Cundiff group.

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.

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.

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.

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 impact on our understanding of the fundamental laws of physics. 

Tauno Palomaki and his colleagues in the Lehnert group have just gone where no one has gone before: They’ve entangled the quantum motion of a vibrating drum with the quantum state of a moving electrical pulse. What’s more, they figured out how to storehalf of this novel entangled state in the drum (which is tiny compared to a musical drum, but huge compared to the atoms or molecules normally entangled in a lab). The drum can then generate another electrical pulse that is entangled with the first one!  This amazing feat was reported in Science.

Research associate Tom Purdy and his colleagues in the Regal group have just built an even better miniature light-powered machine that can now strip away noise from a laser beam. Their secret: a creative workaround of a quantum limit imposed by the Heisenberg Uncertainty Principle. This limit makes it impossible to simultaneously reduce the noise on both the amplitude and phase of light inside interferometers and other high-tech instruments that detect miniscule position changes.

Research associate Bo Yan and his colleagues recently observed spin exchanges in ultracold potassium-rubidium (KRb) molecules inside an optical lattice (a crystal of light formed by interacting laser beams). In solid materials, such spin exchanges are the building blocks of advanced materials and exotic behavior.

Because quantum mechanics is crucial to understanding the behavior of everything in the Universe, one can understand key elements of the behavior of a neutron star by investigating the behavior of an atomic system in the laboratory. This is the promise of the new quantum simulator in the Ye labs. It is a fully controllable quantum system that is being used as a laboratory to study the behavior of other less controllable and more poorly understood quantum systems.

What sets the stage for planet formation? To search for answers to this question, research associate Jake Simon and his colleagues are performing a series of high-level computer simulations of the outer disks around young stars such as TW Hydrae, shown here. Simon’s daunting task is being facilitated with new information that has just started to come in from the Atacama Large Millimeter/submillimeter Array (ALMA) observatory in Chile.

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.

Many people are familiar with the beautiful harmonies created when two sound waves interfere with each other, producing a periodic and repeating pattern that is music to our ears. In a similar fashion, two interfering x-ray waves may soon make it possible to create the fastest possible strobe light ever made. This strobe light will blink fast enough to allow researchers to study the nuclei of atoms and other incredibly tiny structures. The new strobe light is actually very fast coherent laser-like radiation created by the interference of high-energy x-ray waves.

The quantum world is not quite as mysterious as we thought it was. It turns out that there are highways into understanding this strange universe. And, graduate students Minghui Xu and David Tieri with Fellow Murray Holland have just discovered one such superhighway that has been around since the 1950s. Traveling along this superhighway has made it possible to understand the quantum behavior of hundreds of atoms inside every laser used in JILA, including the superradiant laser in the Thompson lab that works entirely differently from all the others.

When research associate Wei Xiong and graduate student Dan Hickstein studied quantum dots by shining laser light on them in the gas phase, they got some surprising results. The tiny chunks of material responded differently to series of two laser pulses — depending on their size. Scientists already knew that most of their quantum dots would end up with at least part of an electron wandering around outside of them for some period of time. However, Xiong and his colleagues showed that the electrons from the smallest quantum dots traveled the farthest away.