Study On Ground-state Cooling And Cooperation Cooling Of The Mechanical Resonator Base On The Hybrid Cavity Optomechanical System

Cavity optomechanics refers to the coupling between optical field and mechanical field,where the radiation pressure of light acts on a mechanical resonator to create momentum transfer inside an optical cavity due to reflection,resulting in the formation of an optomechanical system.This system provides a valuable platform not only for realizing macroscopic quantum phenomena such as quantum coherence and classicalto-quantum transitions but also has important applications in fields such as quantum information processing,and the preparation of various non-classical states.In cavity light force systems,researchers can OMIT mechanical resonators to manipulate cavity fields to realize optical forced-transparent amplification,fast and slow light,optical non-reciprocity,etc.The coherent superposition states and entangled states of mechanical resonators can also be obtained by manipulating the cavity field.However,a prerequisite for realizing these physical phenomena is to cool the mechanical oscillator to its quantum ground state in order to suppress uncontrollable thermal fluctuations as much as possible.Therefore,the cooling of the mechanical resonator to the quantum ground state is a prerequisite to make it potentially useful for applications.In cavity optomechanical,ground state cooling is a key step to realize the quantum effect of mechanical resonator.The cooling model used in this article is based on a compound optical cavity consisting of a Laguerre-Gaussian mode and a Gaussian mode.Under the weak coupling regime,perturbation theory is used to calculate the optomechanical noise spectrum.Based on this noise spectrum,numerical expressions for the steady-state phonon number and the optimal cooling method can be derived.Various parameters are analyzed to investigate their influence on ground state cooling.In the case of strong coupling,the master equation method is used to calculate the expression of the average value of all second-order moment operators containing the steady-state phonon number.This allows for the plot of the steady-state phonon number as a function of time,which can then be used to study the optimal cooling methods.unresolved-sideband cooling is more difficult to achieve experimentally compared to resolved sideband cooling,and often requires the use of auxiliary cavities or electromagnetically induced cooling.In the Laguerre-Gauss-rotating cavity,a movable mirror that can be rotated is added to the cavity,which can achieve a similar effect to electromagnetically induced transparency in the optomechanical system.Distinct peaks and valleys are formed in the optomechanical noise spectrum,where the lower valley is used to suppress the Stokes transition process and the higher peak is used to enhance the anti-Stokes transition process.By adjusting various parameters,ground-state cooling can be achieved under the condition of unresolved sidebands.Building upon this,the paper also introduces a second-order nonlinear optical parametric amplifier(OPA)to enhance the cavity field effect.By adjusting the size of the second-order nonlinear medium gain,it is also possible to achieve ground state cooling under the condition of unresolved sidebands and cool the mechanical resonator to the ground state faster.In addition,the paper studies the issue of synergistic cooling of the mechanical resonator in the composite cavity through the OPA.