Coherent feedback control for cavity optomechanical systems with a frequency-dependent mirror

TL;DR

This paper demonstrates that ground-state cooling of mechanical resonators in a Fano-mirror optomechanical system can be achieved using single-sided coherent feedback, even with high optical losses and in the unresolved-sideband regime.

Contribution

It introduces a novel feedback scheme for ground-state cooling in Fano-mirror optomechanical systems, overcoming limitations of traditional double-sided feedback methods.

Findings

Ground-state cooling is achievable with single-sided feedback in Fano-mirror setups.

Effective cooling occurs despite high optical losses and unresolved-sideband conditions.

Double-sided feedback schemes are less effective for Fano-mirror systems.

Abstract

Ground-state cooling of mechanical resonators is a prerequisite for the observation of various quantum effects in optomechanical systems and thus has always been a crucial task in quantum optomechanics. In this paper, we study how to realize ground-state cooling of the mechanical mode in a Fano-mirror optomechanical setup, which allows for enhanced effective optomechanical interaction but typically works in the (deeply) unresolved-sideband regime. We reveal that for such a two-sided cavity geometry with very different decay rates at the two cavity mirrors, it is possible to cool the mechanical mode down to its ground state within a broad range of parameters by using an appropriate single-sided coherent feedback. This is possible even if the total optical loss is more than seven orders of magnitude larger than the mechanical frequency and the feedback efficiency is relatively low. Importantly, we show that a more standard double-sided feedback scheme is not appropriate to cooperate with a Fano-mirror system.