Study On Optomechanically Induced Transparency And Entanglement In A Two-mechanical-mode Coupled Optomechanical System

An usual cavity optomechanical system(OMS)consists of a half-transmitting fixed mirror and a highly reflective movable mirror,which is harmonically coupled to the cavity optical field by radiation pressure.In recent years,with the continuous development of manufacturing processes of nanotechnology,the size of a mechanical oscillator can be reduced to a micron scale.The scale of the cavity optomechanical system has been greatly reduced,and the coupling effect of light and mechanical oscillators becomes very significant so that the quantum phenomena can be investigated in the mechanical oscillators system.The cavity optomechanical system has many applications,so far,people have done a lot of researches on all kinds of cavity optomechanical system.For example,people have studied the entanglement characteristics of the optomechanical systems to realize the quantum information processing based on the optomechanical platform.For another example,a high-finesse optical micro-cavity can be used to detect extremely weak signals,so it can be used in high precision measurement of weak force,small quality,small displacement.But beyond that,the nonlinear multistability of hybrid optomechanical systems,the cooling of the nanomechanical oscillators to the quantum ground state,the optomechanically induced transparency(OMIT)phenomenon and so on have been the subject of extensive study.In this dissertation,we study a two-mode optomechanical cavity composed of two nanomechanical resonators(NRs)which are coupled by a Coulomb interaction.In Sec.1,we briefly introduce the cavity optomechanical system and its applications.In Sec.2,some theoretical basis of the cavity optomechanical system is introduced.In Sec.3,we propose a scheme for enhancing the mechanical entanglement between the two NRs in the two-mechanical-mode optomechanical cavity,in which the two NRs are coupled by the Coulomb interaction between the charged electrodes loaded on the two oscillators.We findthat the entanglement between the two NRs can be improved by the Coulomb interaction,then the restriction of environment temperature on the entanglement can be relaxed by strengthening the Coulomb coupling.In Sec.4,we consider the OMIT in the entanglement region under different conditions to reduce the optical absorption which suppresses the entanglement.We find that when the two NRs with identical frequencies are coupled to the cavity field by the optomechanical interaction there appears a transparent window near the resonance point,and its transparency window is broader than that in the canonical single-mode optomechanical system under the same conditions.Then the present scheme can provide a wider transparency frequency range for producing the entanglement between the two NRs.Finally,we briefly summarize this dissertation and prospect about the possible researches in the future.