Cooling of micromechanical oscillator in a hybrid optomechanical system with three-level quantum dots

Abstract

We propose a ground state cooling scheme for an optomechanical resonator based on the system of a V-type three-level QD ensemble trapped in a two-mode cavity. The two-mode cavity was pumped by two different deriving fields. We studied the optomechanical cooling under the highly unresolved-sideband and beyond Lamb-Dicke regime (coupling strength between the cavity field and the phonon field not far less than the vibrational frequency). Our results show that the noise spectrum appeared a single peak when the detuning of the QD’s high excitation state and high-frequency driving field equals that of the QD’s low excitation state and low-frequency driving field, otherwise, then appeared double peaks. In the case of double peaks, we can realize the transition between optomechanical cooling and heating by changing the coupling strength of QD with cavity field, which is not available in the case of a single peak. We also studied the evolution of the mean phonon number with time, which is helpful to analyze ground state optomechanical cooling.