Millionfold improvement in multivibration-feedback optomechanical refrigeration via auxiliary mechanical coupling

TL;DR

This paper demonstrates a method to significantly enhance multivibration optomechanical cooling rates using auxiliary mechanical coupling, enabling ground-state cooling beyond the resolved-sideband regime.

Contribution

It introduces an auxiliary mechanical coupling technique that removes dark modes, achieving over six orders of magnitude improvement in cooling rates and enabling ground-state cooling in the bad-cavity regime.

Findings

Amplification of net-refrigeration rates by over six orders of magnitude.

Ground-state cooling beyond the resolved-sideband regime achieved with auxiliary mechanical coupling.

Dark mode removal is essential for enhanced cooling performance.

Abstract

The simultaneous ground-state refrigeration of multiple vibrational modes is a prerequisite for observing significant quantum effects of multiple-vibration systems. Here we propose how to realize a large amplification in the net-refrigeration rates based on cavity optomechanics and to largely improve the cooling performance of multivibration modes beyond the resolved-sideband regime. By employing an auxiliary mechanical coupling (AMC) between two mechanical vibrations, the dark mode, which is induced by the coupling of these vibrational modes to a common optical mode and cuts off cooling channels, can be fully removed. We use fully analytical treatments for the effective mechanical susceptibilities and net-cooling rates and find that when the AMC is turned on, the amplification of the net-refrigeration rates by more than six orders of magnitude can be observed. In particular, we reveal that the simultaneous ground-state cooling beyond the resolved-sideband regime arises from the introduced AMC, without which it vanishes. Our work paves the way for quantum control of multiple vibrational modes in the bad-cavity regime.