Ground-state cooling of a micromechanical oscillator: generalized framework for cold damping and cavity-assisted cooling schemes

TL;DR

This paper presents a comprehensive framework for cooling micromechanical oscillators to their quantum ground state using radiation-pressure coupling, analyzing two schemes and identifying their optimal conditions.

Contribution

It introduces a generalized theoretical framework applicable to multiple cooling schemes and determines their quantum limits across different cavity regimes.

Findings

Back-action cooling is more efficient in the good cavity limit.

Cold-damping cooling is more suitable in the bad cavity limit.

Previous models are special cases within this generalized framework.

Abstract

We provide a general framework to describe cooling of a micromechanical oscillator to its quantum ground state by means of radiation-pressure coupling with a driven optical cavity. We apply it to two experimentally realized schemes, back-action cooling via a detuned cavity and cold-damping quantum-feedback cooling, and we determine the ultimate quantum limits of both schemes for the full parameter range of a stable cavity. While both allow to reach the oscillator's quantum ground state, we find that back-action cooling is more efficient in the good cavity limit, i.e. when the cavity bandwidth is smaller than the mechanical frequency, while cold damping is more suitable for the bad cavity limit. The results of previous treatments are recovered as limiting cases of specific parameter regimes.