Optomechanical Cavity Cooling of an Atomic Ensemble

TL;DR

This paper demonstrates cavity sideband cooling of an atomic ensemble's collective motional mode to near ground state, aligning with theoretical models and highlighting the cooperative nature of the cooling process.

Contribution

It presents the first experimental realization of cavity cooling of an atomic ensemble's collective mode, confirming theoretical predictions and exploring fundamental cooling limits.

Findings

Achieved mean phonon occupation number of 2.0

Cooling rate proportional to photon scattering rate

Good agreement with optomechanical model

Abstract

We demonstrate cavity sideband cooling of a single collective motional mode of an atomic ensemble down to a mean phonon occupation number of 2.0(-0.3/+0.9). Both this minimum occupation number and the observed cooling rate are in good agreement with an optomechanical model. The cooling rate constant is proportional to the total photon scattering rate by the ensemble, demonstrating the cooperative character of the light-emission-induced cooling process. We deduce fundamental limits to cavity-cooling either the collective mode or, sympathetically, the single-atom degrees of freedom.