Sensing force gradients with cavity optomechanics while evading backaction

TL;DR

This paper demonstrates a method for sensing force gradients using cavity optomechanics with phase-sensitive detection, achieving extended monotonic response and minimal backaction, beneficial for high-precision measurements like atomic force microscopy.

Contribution

It introduces a two-tone backaction evading measurement technique that enhances force-gradient sensing while reducing measurement backaction in cavity optomechanics.

Findings

Extended monotonic response to force gradients.

Minimal backaction comparable to standard backaction evading methods.

Potential applications in atomic force microscopy.

Abstract

We study force-gradient sensing with a coherently driven mechanical resonator and phase-sensitive detection of motion through the two-tone backaction evading measurement of cavity optomechanics. The response of the optomechanical system, solved by numerical integration of the classical equations of motion, shows an extended region which is monotonic to changes in force gradient. We use Floquet theory to model the fluctuations, which rise only slightly above that of the usual backaction evading measurement in the presence of the mechanical drive. The monotonic response and minimal backaction are advantageous for applications such as atomic force microscopy.