Abstract

A single Hg⁺ ion that is confined in an rf (Paul) trap can be laser cooled so that the amplitude of its motion is much less than an optical wavelength (the Dicke limit for optical transitions).¹ More recently, we used the technique of sideband cooling to reach the zero point of motion.² This realizes for the first time, we believe, the fundamental limit of laser cooling and the ideal of an isolated atomic particle at rest in free space to within the quantum mechanical limits imposed by the surrounding apparatus. In both limits, Doppler effects to all orders become negligible, the interrogation time is arbitrarily long, and the fundamental shot noise limit of a single atom is readily attained. We report these results and our progress toward the ²S_1/2—²D_5/2 282-nm transition with a resolution approaching the 2-Hz natural linewidth.

© 1988 Optical Society of America