Improving the optomechanical entanglement and cooling by photothermal force

TL;DR

This paper explores how photothermal forces can enhance optomechanical cooling and entanglement, providing new analytical models and demonstrating improved quantum control in such systems.

Contribution

It introduces a novel photothermal model, derives an exact relation for phonon number, and shows how photothermal forces improve cooling and entanglement in optomechanical systems.

Findings

Photothermal force enhances ground state cooling at strong coupling.

Photothermal effects improve optomechanical entanglement.

Cross correlation between radiation pressure and photothermal force is significant.

Abstract

Cooling and Entanglement in optomechanical systems coupled through radiation pressure and photothermal force is studied. To develop the photothermal model, we derive an expression for deformation constant of the force. Exploiting linearized quantum Langevin equations we investigate dynamics of such systems. According to our analysis, in addition to separate action of radiation pressure and photothermal force, their cross correlation effect plays an important role in dynamics of the system. We also achieve an exact relation for the phonon number of the mechanical resonator in such systems, and then we derive an analytical expression for it at weak coupling limit. At strong coupling regime, we show that utilizing the photothermal pressure makes the ground state cooling more approachable. The effect of photothermal force on the optomechanical entanglement is investigated in detail. According to our exact numerical and approximate analytical studies, even though the photothermal force is naturally a dissipative force, it can improve the optomechanical entanglement both quantitatively and qualitatively.