Phonon number quantum jumps in an optomechanical system

TL;DR

This paper demonstrates how phonon number quantum jumps in an optomechanical system can be inferred through homodyne detection, highlighting the conditions for observing these jumps and simulating their dynamics.

Contribution

It introduces a method to detect phonon quantum jumps via optical measurements and analyzes the conditions necessary for their observation in optomechanical systems.

Findings

Quantum jumps in phonon number can be inferred from optical measurements.

High measurement rate and low thermalization are essential for observing jumps.

Simulations show clear phonon entry and exit events in the mechanical resonator.

Abstract

We describe an optomechanical system in which the mean phonon number of a single mechanical mode conditionally displaces the amplitude of the optical field. Using homodyne detection of the output field we establish the conditions under which phonon number quantum jumps can be inferred from the measurement record: both the cavity damping rate and the measurement rate of the phonon number must be much greater than the thermalization rate of the mechanical mode. We present simulations of the conditional dynamics of the measured system using the stochastic master equation. In the good-measurement limit, the conditional evolution of the mean phonon number shows quantum jumps as phonons enter and exit the mechanical resonator via the bath.