Optomechanical back-action evading measurement without parametric instability

TL;DR

This paper reviews a scheme for back-action evading measurement in optomechanics, introducing a simple modification to eliminate parametric instability and enable measurements below the quantum zero-point level.

Contribution

The paper proposes a straightforward modification to the optical drive that prevents parametric instability, enhancing the feasibility of high-precision quantum measurements.

Findings

Parametric instability can be suppressed at high intracavity power.

The modified scheme enables sub-zero-point quadrature measurements.

Experimental implementation becomes more practical with the proposed modification.

Abstract

We review a scheme for performing a back-action evading measurement of one mechanical quadrature in an optomechanical setup. The experimental application of this scheme has been limited by parametric instabilities caused in general by a slight dependence of the mechanical frequency on the electromagnetic energy in the cavity. We find that a simple modification to the optical drive can effectively eliminate the parametric instability even at high intracavity power, allowing realistic devices to achieve sub-zero-point uncertainties in the measured quadrature.