Optomechanical Backaction in the Bistable Regime

TL;DR

This paper demonstrates that optomechanical systems can achieve backaction cooling of mechanical resonators even in the nonlinear, bistable regime, challenging the conventional view that nonlinearity hampers cooling.

Contribution

It introduces a theoretical framework accounting for cavity nonlinearity, enabling precise predictions of backaction cooling beyond the bifurcation point in optomechanical systems.

Findings

Backaction cooling is feasible in the nonlinear regime.

Cavity nonlinearity affects the photon spectrum shape.

Predictions remain accurate beyond the bifurcation point.

Abstract

With a variety of realisations, optomechanics utilizes its light matter interaction to test fundamental physics. By coupling the phonons of a mechanical resonator to the photons in a high quality cavity, control of increasingly macroscopic objects has become feasible. In such systems, state manipulation of the mechanical mode is achieved by driving the cavity. To be able to achieve high drive powers the system is typically designed such that it remains in a linear response regime when driven. A nonlinear response and especially bistability in a driven cavity is often considered detrimentally to cooling and state preparation in optomechanical systems and is avoided in experiments. Here we show, that with an intrinsic nonlinear cavity backaction cooling of a mechanical resonator is feasible operating deeply within the nonlinear regime of the cavity. With our theory taking the nonlinearity into account, precise predictions on backaction cooling can be achieved even with a cavity beyond the bifurcation point, where the cavity photon number spectrum starts to deviate from a typical Lorentzian shape.