The Study On Stationary Macroscopic Entanglement Based On The Optomechanical System Under The Environment Of Reservoir Noise

With the rapid development of micro-nano manufacturing and materials pre-cessing technology,now the mechanical oscillator has entered the age of micro-nano scale and has the dynamic characteristics of the classical mechanics and quantum mechanics at the same time.With the gradual emergence of high-quality optical cav-ity,the manipulation of mechanical oscillator by the optical field which is enhanced via the optical cavity is no longer a daydream.The cavity optomechanical system which is combined by the micro-nano mechanical oscillator and the optical cavity provides an ideal platform for the observation of macroscopic quantum phenomena and the test of quantum theory.In the meanwhile,the cavity optomechanical system has the widely promissing applications in the field of high-precision measuremen-t,such as micro-mass measurement,micro-displacement measurement,weak force measurement,weak signal measurement,gravitational-wave detection,and so on.Therefore,the cavity optomechanical system,recently,has raised widespread at-tention and great interest and has become a new research hotspot.In this thesis,under the environment of reservoir noise,we investigate the stationary entangle-ment behavior based on the optomechanical system and the main contents are as follows:Based on the coupled cavity optomechanical system,we propose a scheme for the realization of stationary macroscopic entanglement between the movable mirror and atomic ensemble which are indirectly interacted.We numerically simulate the entanglement logarithmic negativity between the movable mirror and atomic ensem-ble by choosing the feasible parameters experimentally.The numerical simulation result shows that the stronger coupling strength of the coupled cavity not only en-hances the entanglement,but also widens the effective detuning region.And the smaller damping rate of the mechanical oscillator can significantly raise the critical temperature of entanglement.Specifically,when ?m=10-6?m,the numerical sim-ulation result shows that the critical temperature can up to 170 K,which breaks the liquid nitrogen cooling and liquid helium cooling and largely lowers down the experiment cost for the realization and observation of the macroscopic entanglement.Under the auxiliary of the cavity optomechanical system,we investigate the classical-to-quantum transition behavior between two oscillators separated in space which are coupled through Coulomb interaction.Via numerically simulating the en-tanglement logarithmic negativity between the two oscillators separated in space,we find that the Coulomb coupling interaction is the direct cause of entanglement,the reservoir noise is the main obstacle of obtaining entanglement and the optomechan-ical coupling is the effective method to suppress the detrimental effects of reservoir noise.Resorting to the squeezing of the cavity field generated by an optical para-metric amplifier(OPA)inside the cavity,we discuss the effect of squeezed light driving on this classical-to-quantum transition behavior.Due to the competition effect between the cavity optomechanical coupling and the Coulomb coupling,we find that the effects of the gain and the pump driving phase of the OPA are oppo-site.In addition,the robustness of the entanglement will be strengthened with the increase of the gain and the driving power.At last,we also consider the effect of the frequency detuning between the oscillators on the entanglement behavior.