Research Of The Macroscopic Quantum Coherence And The Modulated Dynamics Of The Entanglement And Cooling In Cavity Optomechanical System

In recent years,the dispersive coupling mechanism between the optical field and the mechanical oscillator in the cavity optomechanical system has attracted extensive attention in the study of quantum correlation.Quantum correlation such as quantum coherence and quantum entanglement plays a very important role in quantum information and quantum computation.Exploring the quantum coherence,quantum entanglement,is helpful for us to realize the high and stable quantum correlation in macroscopic system.We theoretically study the quantum coherence in mechanical oscillators and its transfer between the cavity and mechanical modes of the optomechanical system comprising an optical cavity and two mechanical oscillators that,in this study,were simultaneously coupled to the optical cavity at different optomechanical coupling strengths.The quantum coherence transfer between the optical and mechanical modes is found to depend strongly on the relative magnitude of the two optomechanical couplings.The laser power,decay rates of the cavity and mechanical oscillators,environmental temperature,and frequency of the mechanical oscillator are observed to significantly influence the investigated quantum coherences.Moreover,quantum coherence generation in the optomechanical system is restricted by the system's stability condition,which helps sustain high and stable quantum coherence in the cavity optomechanical system.We also theoretically study the dynamics of the ground-state cooling and the quantum entanglement in a modulated optomechanical system,where the frequency of the mechanical oscillator and the optical field or the strength of the driving laser is time dependent.In the long-time limit the steady-state phonon number can be decreased significantly so that the mechanical oscillator is cooled to the ground state by appropriately selecting the frequency and the amplitude of the modulation.Further,the entanglement between optical field and mechanical oscillator is promoted when the phonon number keeps in a low value.With the enhanced nonlinear by modulation,the dynamics of the entanglement preevaluation value exhibits a quasiperiodic behavior.It can help us to prepare and manipulate the quantum property in the cavity optomechanical system.