Reaching a record low temperature.

It's getting colder in the laboratory. Physicists at the National Institute of Standards and Technology (NIST) in Gaithersburg, Md., have chilled atoms to 700 nanokelvins, a temperature barely above absolute zero. Although other researchers have reached lower temperatures either transiently or in one or two dimensions, this represents the lowest temperature yet attained involving the motion of atoms in three dimensions.

The NIST team achieved the new record using a technique borrowed from researchers at the Ecole Normale Superieure in Paris (SN: 7/16/94, p.47). William D. Phillips and his colleagues at NIST trapped cesium atoms in an "optical lattice" created by four intersecting laser beams. Oscillating back and forth in the "hollows" of this lattice, the trapped atoms reach a temperature close to 1 microkelvin. Reducing the laser intensity drives the temperature to 700 nK, slowing the atoms to an average velocity of 7 millimeters per second.