Multimode Optomechanical Cooling via General Dark-Mode Control

Abstract

The dark-mode effect is a stubborn obstacle for ground-state cooling of multiple degenerate mechanical modes optomechanically coupled to a common cavity-field mode. Here we propose an auxiliary-cavity-mode scheme for simultaneous ground-state cooling of two degenerate or near-degenerate mechanical modes by breaking the dark mode. We find that the introduction of the auxiliary cavity mode not only breaks the dark-mode effect, but also provides a new cooling channel to extract the thermal excitations stored in the dark mode. We also study the general physical-coupling configurations for breaking the dark mode in a generalized network-coupled four-mode optomechanical system consisting of two cavity modes and two mechanical modes. We derive the analytical dark-mode-breaking condition in this system. Our results not only provide a general method to control various dark-mode and dark-state effects in physics, but also pave the way to the study of macroscopic quantum phenomena and applications in multiple-mechanical-resonator systems.