Simultaneous Cooling Of Two Mechanical Oscillators In A Cavity Optomechanical System

Cavity optomechanics as an important branch of physical optics,mainly studies the interaction between light and mechanical objects.Through the manipulation of the optical-mechanical coupling system,researchers have discovered many unique quantum phenomena of the optical system,and have been widely used in many fields,such as high-precision measurement,quantum information processing,gravitational wave detec-tion and verification of quantum basic principles.With the continuous development of nano-manufacturing technology,the nano-mechanical oscillator in the optical cavity has become an important platform for studying macroscopic quantum effects and exploring new applications in this field.Due to the low frequency of the mechanical oscillator,it is easy to be excited by the external thermal environment and generate thermal noise,which hinders the subsequent research on quantum phenomena.Therefore,the cooling of the mechanical oscillator is of great significance.Generally,when the steady state phonon number of the mechanical oscillator is less than one,the ground state cooling of the mechanical oscillator is considered to have been achieved.In this dissertation,we propose a research scheme for simultaneous cooling of two mechanical oscillators under the condition of resolved sideband(?(?)?_m).A degenerate optical parametric amplifier(OPA)is placed in an optical cavity consisting of two moving mirrors.The process of parametric amplification in the optical cavity changes the quantum statistical properties of the cavity field and improves the coupling strength between the cavity field and the mechanical oscillator.Since there are two mechanical oscillators in the system,when the frequencies of two mechanical oscillators are the same,the existence of the second mechanical oscillator will lead to a sharp decrease in the effective mechanical damping rate of the other mechanical oscillator.The interaction between them will make the cooling process tend to"destruct interference",so that the purpose of cooling can not be achieved.In order to avoid such adverse effects in the cooling process,two mechanical oscillators with different frequencies were selected for the study.By adjusting the parametric gain and phase of the optical parametric amplifier,it is found that the two mechanical oscillators can be cooled to close to their quantum ground state at the same time,and the time required for the cooling process to stabilize is greatly reduced.