ABSTRACT
This chapter describes the National Bureau of Standards’ Observation of Atoms Laser-Cooled Below the Doppler Limit, relating the context in which the publication appeared, its impact on science, technology, and the general public, and brief details about the lives and work of the author. By carefully choosing the frequency of the laser, it appeared possible to cause the atoms to emit light at a slightly higher frequency (energy) than they absorbed, carrying away the thermal energy of the atom. This frequency difference derived from the Doppler shift due to the motion of the atoms. The sub-Doppler laser-cooling temperature for cesium can be 100 times lower than the Doppler limit. Using an idea from 1954, well ahead of its time but now made possible with sub-Doppler laser cooling, the cesium atoms form an atomic fountain, undergoing a one meter high parabolic trajectory in the earth's gravitational field with a resulting hundred-fold increase in the observation time.
