Simultaneous cooling of degenerate mechanical modes in unresolved sideband regime via optical and mechanical nonlinearities

TL;DR

This paper presents a novel scheme to cool multiple degenerate mechanical modes simultaneously in optomechanical systems beyond the resolved sideband regime, overcoming dark-mode effects using mechanical and optical nonlinearities.

Contribution

The scheme introduces mechanical and optical nonlinearities to enable ground-state cooling of degenerate modes beyond the resolved sideband regime.

Findings

Dark mode of degenerate modes can be broken with mechanical nonlinearities.

Optical nonlinearity helps achieve ground-state cooling beyond the resolved sideband regime.

Scheme facilitates simultaneous cooling of degenerate mechanical modes.

Abstract

We propose a scheme to simultaneously cool multiple degenerate mechanical modes in optomechanical systems beyond the resolved sideband regime. In general, one of the main obstacles for cooling degenerate mechanical modes is the so-called dark-mode effect. The Duffing nonlinearities (mechanical nonlinearities) can be used to overcome the dark-mode effect of degenerate mechanical modes. A second-order nonlinear medium (optical nonlinearity) is introduced to accomplish the ground-state cooling of degenerate mechanical modes beyond the resolved sideband regime. We find the dark mode of degenerate mechanical modes can be broken when the mechanical nonlinearities of different mechanical modes are not very close. Our scheme paves the way toward the implementation of simultaneous ground-state cooling of degenerate mechanical modes of optomechanical systems beyond the resolved sideband regime in experiments.