Quantum Theory of Cavity-Assisted Sideband Cooling of Mechanical Motion

TL;DR

This paper develops a comprehensive quantum model for cavity-assisted sideband cooling of mechanical oscillators, highlighting the importance of the resolved sideband regime for reaching quantum ground states.

Contribution

It introduces a fully quantum theoretical framework for opto-mechanical cooling, emphasizing the necessity of the good cavity regime for quantum limit achievement.

Findings

Quantum limit requires resolved sideband regime

Cooling rate derived from quantum noise approach

Minimum phonon number depends on cavity linewidth

Abstract

We present a fully quantum theory describing the cooling of a cantilever coupled via radiation pressure to an illuminated optical cavity. Applying the quantum noise approach to the fluctuations of the radiation pressure force, we derive the opto-mechanical cooling rate and the minimum achievable phonon number. We find that reaching the quantum limit of arbitrarily small phonon numbers requires going into the good cavity (resolved phonon sideband) regime where the cavity linewidth is much smaller than the mechanical frequency and the corresponding cavity detuning. This is in contrast to the common assumption that the mechanical frequency and the cavity detuning should be comparable to the cavity damping.