Phillips, William Daniel (1948-…), an American physicist, shared the 1997 Nobel Prize for physics with fellow American Steven Chu and a French physicist, Claude Cohen-Tannoudji, who did separate work in the same area (see Chu, Steven ; Cohen-Tannoudji, Claude ). Phillips works in the field of laser cooling of atoms–using laser beams to slow down the random movements of atoms in a gas until they are nearly stationary, so that they can be more closely studied. Phillips seeks to apply the techniques he has developed in pure science to technological applications such as ultra-accurate clocks and in microelectronics.
Phillips was born in Wilkes-Barre, Pennsylvania, and gained a doctorate at the Massachusetts Institute of Technology. After postdoctoral work there, he joined the National Bureau of Standards (later to become the National Institute of Standards and Technology–NIST) at Gaithersburg, Maryland, in 1978, where he worked on precise electrical measurements. But in his spare time, he experimented with the laser cooling of atoms.
Atoms move fast in hot materials, slow in cold ones. Phillips showed that a stream of atoms could be slowed with beams of laser light. His investigations grew into a long-term program of research by NIST. In 1985, he and his colleagues succeeded in slowing atoms and trapping them using a magnetic field. The scientists reduced the temperature of an atomic beam from room temperature to a tenth of a Celsius degree above absolute zero (-273.15 °C). See Absolute zero .
A few years later, Phillips and his group adopted a new invention, a type of atom trap called a magneto-optical trap, which enabled them to achieve still lower temperatures, about 40 millionths of a Celsius degree above absolute zero. This temperature was lower than scientists had previously thought possible, and theorists had to revise their ideas to account for it. Today, workers in this field have cooled atoms to within a few millionths of a degree of absolute zero.
