Manfred Salmhofer

Certain materials, near absolute zero, superconduct: electricity flows without loss. The critical temperature starts this. John Bardeen and colleagues explained that atomic vibrations glue electrons into Cooper pairs.

In an ultracold cloud of 180,000 lithium atoms, about a thousand cesium atoms drift. They are 22 times heavier than their neighbors, which makes them nearly motionless among the fast-moving particles. When such a heavy atom absorbs light, it starts oscillating between two states, and the rate of these oscillations is called the Rabi frequency.