Selective cooling and squeezing in a lossy optomechanical closed loop embodying an exceptional surface

TL;DR

This paper investigates a lossy optomechanical system with two mechanical resonators, demonstrating how non-Hermiticity near exceptional points enhances cooling and squeezing, with potential for frequency-dependent control in quantum technologies.

Contribution

It introduces a novel analysis of a synthetic optomechanical plaquette, revealing how exceptional points and surfaces influence quantum control of mechanical resonators.

Findings

Non-Hermiticity enhances cooling and squeezing near exceptional points.

Exceptional surface ensures robustness of exceptional point effects.

Frequency-dependent cooling and squeezing are achievable near the red-sideband.

Abstract

A closed-loop, lossy optomechanical system consisting of one optical and two degenerate mechanical resonators is computationally investigated. This system constitutes an elementary synthetic plaquette derived from the loop phase of the intercoupling coefficients. In examining a specific quantum attribute, we delve into the control of quadrature variances within the resonator selected through the plaquette phase. An amplitude modulation is additionally applied to the cavity-pumping laser to incorporate mechanical squeezing. Our numerical analysis relies on the integration-free computation of steady-state covariances for cooling and the Floquet technique for squeezing. We provide physical insights into how non-Hermiticity plays a crucial role in enhancing cooling and squeezing in proximity to exceptional points. This enhancement is associated with the behavior of complex eigenvalue loci as a function of the intermechanical coupling rate. Additionally, we demonstrate that the parameter space embodies an exceptional surface, ensuring the robustness of exceptional point singularities under experimental parameter variations. However, the pump laser detuning breaks away from the exceptional surface unless it resides on the red-sideband by an amount sufficiently close to the mechanical resonance frequency. Finally, we show that this disparate parametric character entitles frequency-dependent cooling and squeezing, which is of technological importance.