Two-Tone Optomechanical Instability and Its Fundamental Implications for Backaction-Evading Measurements

Itay Shomroni,Tobias J Kippenberg,Amir Youssefi,Liu Qiu,Andreas Nunnenkamp,Paul Seidler,Nick Sauerwein,Daniel Malz

doi:10.1103/physrevx.9.041022

Abstract

Experiments reveal a novel optomechanical instability in devices that attempt to surpass quantum limits in ultraprecise displacement measurements, an effect that must be considered in future quantum sensing experiments.

Highlights

Interferometric position measurement of mechanical oscillators is the underlying principle of the Laser Interferometer Gravitational Observatory (LIGO) [1] and constitutes one of the most sensitive techniques for determining absolute distance available to date
Since the constraints on tuning accuracy become stricter with increasing probe power, the instability imposes a fundamental limitation on BAE measurements as well as other two-tone schemes, such as dissipative squeezing of optical and microwave fields or of mechanical motion
In addition to identifying a new limitation in two-tone BAE measurements, the results introduce a new type of nonlinear dynamics in cavity optomechanics

Summary

INTRODUCTION

Interferometric position measurement of mechanical oscillators is the underlying principle of the Laser Interferometer Gravitational Observatory (LIGO) [1] and constitutes one of the most sensitive techniques for determining absolute distance available to date. It stands in contrast to previously reported instabilities in BAE measurements associated with parametric driving [43,44], where the underlying cause has been attributed to the dependence of the mechanical frequency on temperature [45] or the presence of two-level systems [46] In this sense, the two-tone instability poses fundamental constraints, and one may need to resort to active feedback techniques, as in the case of the parametric oscillatory instability [31,47]. In recent work on noiseless single-quadrature amplification of mechanical motion [53], the squeezing effect we report here produces significant deviations from the expected system behavior

OBSERVATION OF INSTABILITY IN TWO-TONE PUMPING

THEORY

EXPERIMENT

CONCLUSION