Deeper Cooling of Micromechanical Motion by Quadrature Squeezing Beyond the Resolved Sideband Limit

Cavity optomechanics provides a unique platform to control the micro-mechanical systems by optical fields which covers the classical-quantum boundary to fulfill the theoretical foundations of quantum technologies. The opto-mechanical resonators are the promising candidates to develop precisely controlled nano-motors, ultra-sensitive sensors and robust quantum information processors. For all these applications, a crucial step is to cool the micro-mechanical resonators down to their quantum ground states with a very low effective temperature. In this paper, we come up with a novel approach to further cool the micro-mechanical resonator by making use of the quadrature squeezing effect. One hotter quadrature with an enhanced fluctuation induced by the squeezing of the other can be further cooled by the conventional optomechanical couplings. Our theoretical and numerical investigations demonstrate that this method is physically feasible and practically effective for deeper cooling of the mechanical resonator to its coldest temperature ever.