Nonreciprocal ground-state cooling of multiple mechanical resonators

TL;DR

This paper introduces a universal method to achieve simultaneous ground-state cooling of multiple mechanical resonators by breaking dark modes through phased-dependent phonon exchange, enabling nonreciprocal energy transfer.

Contribution

The proposed approach effectively breaks dark modes using a loop-coupled configuration, allowing for reliable cooling of multiple mechanical modes in cavity optomechanics.

Findings

Achieves simultaneous ground-state cooling of multiple mechanical modes.

Demonstrates nonreciprocal phonon transfer mechanism.

Generalizable to break other dark-state effects in physics.

Abstract

The simultaneous ground-state cooling of multiple degenerate or near-degenerate mechanical modes coupled to a common cavity-field mode has become an outstanding challenge in cavity optomechanics. This is because the dark modes formed by these mechanical modes decouple from the cavity mode and prevent extracting energy from the dark modes through the cooling channel of the cavity mode. Here we propose a universal and reliable dark-mode-breaking method to realize the simultaneous ground-state cooling of two degenerate or nondegenerate mechanical modes by introducing a phasedependent phonon-exchange interaction, which is used to form a loop-coupled configuration. We find an asymmetrical cooling performance for the two mechanical modes and expound this phenomenon based on the nonreciprocal energy transfer mechanism, which leads to the directional flow of phonons between the two mechanical modes. We also generalize this method to cool multiple mechanical modes. The physical mechanism in this cooling scheme has general validity and this method can be extended to break other dark-mode and dark-state effects in physics.