Improving force sensitivity by amplitude measurement of light reflected from a detuned optomechanical cavity

TL;DR

This paper proposes a scheme for coherent back-action cancellation in optomechanical cavities, enhancing force sensitivity by measuring the amplitude quadrature of reflected light to reduce quantum back-action effects.

Contribution

It introduces a novel method for quantum back-action cancellation using amplitude measurement in a detuned optomechanical cavity, improving sensitivity without additional squeezing or complex readout.

Findings

Demonstrated back-action cancellation in a detuned cavity

Achieved improved force sensitivity limited by quantum back-action

Provided a simple method applicable to various optomechanical experiments

Abstract

The measurement of weak continuous forces exerted on a mechanical oscillator is a fundamental problem in various physical experiments. It is fundamentally impeded by quantum back-action from the meter used to sense the displacement of the oscillator. In the context of interferometric displacement measurements, we here propose and demonstrate the working principle of a scheme for coherent back-action cancellation. By measuring the amplitude quadrature of the light reflected from a detuned optomechanical cavity inside which a stiff optical spring is generated, back-action can be cancelled in a narrow band of frequencies. This method provides a simple way to improve the sensitivity in experiments limited by quantum back-action without injection of squeezed light or stable homodyne readout.