�Թ���

A large fraction of JILA research relies on laser cooling of atoms, ions and molecules for applications as diverse as world-leading atomic clocks, human-controlled chemistry, quantum information, new forms of ultracold matter and the search for new details of the origins of the universe. JILAns use laser cooling every day in their research, and have mastered arcane details of the process.

Getting lasers to have a precise single frequency (color) can be trickier than herding cats. So it’s no small accomplishment that the Thompson group has figured out how to use magnetic fields to create atomic cowpokes to wrangle a specific single color into place so that it doesn’t wander hither and yon. The researchers do this with a magnetic field that causes strontium atoms in an optical cavity to stop absorbing light and become transparent to laser light at one specific color. What happens is that the magnetic field creates a transparent window that serves as a gate to let only light of a single frequency pass through.

In the Ye group’s new quantum simulation experiment, cold strontium atoms, which are analogs of electrons, are allowed to tunnel between the pancakes that confine the atoms with laser light. Because the atoms moving in an array of pancakes are analogs of electrons moving in solids, such studies are expected to shed light on the complex physics of metals and other solids.

Dynamical phase transitions in the quantum world are wildly noisy and chaotic. They don’t look anything like the phase transitions we observe in our everyday world. In Colorado, we see phase transitions caused by temperature changes all the time: snow banks melting in the spring, water boiling on the stove, slick spots on the sidewalk after the first freeze. Quantum phase transitions happen, too, but not because of temperature changes. Instead, they occur as a kind of quantum “metamorphosis” when a system at zero temperature shifts between completely distinct forms.

The spooky quantum property of entanglement is set to become a powerful tool in precision measurement, thanks to researchers in the Thompson group. Entanglement means that the quantum states of something physical—two atoms, two hundred atoms, or two million atoms—interact and retain a connection, even over long distances.

James Thompson has been named the winner of a 2013 Department of Commerce Bronze Medal for his work on pioneering superradiant lasers. The superradiant laser is a quantum device that emits coherent lasing photons.