The optomechanical instability in the quantum regime

TL;DR

This paper explores the quantum regime of optomechanical systems, analyzing the transition from classical to quantum behavior through numerical solutions of the quantum master equation and examining key physical observables.

Contribution

It provides a detailed quantum analysis of optomechanical instability, highlighting quantum effects and the quantum-to-classical transition in such systems.

Findings

Quantum effects influence the mechanical energy and phonon distribution.

The quantum-to-classical transition depends on a specific quantum parameter.

Numerical solutions reveal differences from classical predictions.

Abstract

We consider a generic optomechanical system, consisting of a driven optical cavity and a movable mirror attached to a cantilever. Systems of this kind (and analogues) have been realized in many recent experiments. It is well known that those systems can exhibit an instability towards a regime where the cantilever settles into self-sustained oscillations. In this paper, we briefly review the classical theory of the optomechanical instability, and then discuss the features arising in the quantum regime. We solve numerically a full quantum master equation for the coupled system, and use it to analyze the photon number, the cantilever's mechanical energy, the phonon probability distribution and the mechanical Wigner density, as a function of experimentally accessible control parameters. We observe and discuss the quantum-to-classical transition as a function of a suitable dimensionless quantum parameter.