Parametric feedback cooling of a single atom inside an optical cavity

Abstract

A single atom coupled to a single mode of an optical cavity can serve as an elementary building block in a distributed quantum network [1] or as a kind of amplifier for studying quantum features of matter-light interactions that are hard to detect in free space, such as squeezing [2]. Most such experiments make use of strong coupling between atom and cavity mode, which requires that the atom is well localized. Experimentally, this can be achieved using feedback on the atomic motion: from intensity variations of a probe beam transmitted through the cavity information about the atomic motion is gained, which is used to synchronously modulate the trapping potential holding the atom, leading to cooling and better localization.