Light-Mechanical Entanglement And Preparation Of Non-Gaussian Nonclassical Mechanical States In Dissipative Cavity Optomechanical Systems

Quantum entanglement is one of the most significant characteristics of quantum mechanics and the basic resource of quantum information processing.At present,cavity optomechanics is the frontier research area of quantum optics.The object of study for cavity optomechanics is the coupling system of radiation field and micromechanical oscillator.The cavity optomechanical systems can be used not only to study the quantum properties of macroscopical objects,but also to realize the quantum information processing based on macroscopic system.In addition,the quantum control of the light field on the mechanical oscillator can be realized by the coupling of optomechanics.And the quantum manipulation of the light field can be realized by using the oscillator.In this paper,the entanglement of light field and oscillator in dissipative optomechanical system are researched and the nonGaussian nonclassical mechanical state is realized by using the photon reduction operation.First,we study the entanglement between the light field and the mechanical oscillator in the dissipative cavity optomechanical systems.The dissipative coefficient of the cavity field in the dissipative optomechanical systems changes with the position of the oscillator,thus achieving the coupling between the resonator and the cavity field.By using the Hamiltonian of the system,the linear Langevin equation of the dissipative cavity optomechanical systems is derived,and the correlation matrix of the system is derived from the motion equation of the system.The entanglement characteristics of the coupling between optical field and mechanical oscillator of the dissipative cavity optomechanical systems are discussed.It is found that the dissipative cavity optomechanical systems has a strong entanglement in the bad cavity and the blue detuning.It is different from the dispersion type cavity optomechanical systems,and the latter produces relatively weak entanglement in the case of a good red detuning cavity.This is due to that the stability conditions of the dissipative cavity optomechanical systems under the blue detuning and the strong coupling intensity of the light force can be satisfied.While the system satisfies the stability condition when the dispersive optomechanical systems has a weak coupling intensity,and the entanglement of the system is relatively weak.Secondly,we also discuss the quantum entanglement between the output field and the mechanical oscillator in the dissipative optomechanical systems.A specific output field with a certain line width and a central frequency is selected by the filter function,and the entanglement between the output field and the oscillator is discussed.By comparing with the inner cavity field,it is found that in the blue detuning and the red detuning region,even the light force coupling intensity is weak,it can produce obvious optomechanical entanglement.In the cavity only under the blue detuning,when the optomechanical coupling coefficient is very great,the relatively large entanglement can be reached.Finally,in this paper,the nonGaussian nonclassical mechanical state is obtained by implementing the photon reduction operation on the output light field in the dissipative cavity optomechanical systems.The nonclassical properties of the quantum state are discussed by using the Wigner function of the condition state of the mechanical oscillator.We find that under certain parameters,the Wigner function has a negative value,which shows that the obtained mechanical quantum state presents nonGaussian nonclassical property.