Research On Cavity Optomechanical Squeezed Cooling Based On Optical Parametric Amplifier

Cavity optomechanics is a cutting-edge interdisciplinary research field involving quantum optics and materials science,which studies the modulation of both the optical field and mechanical resonators,as well as their interactions with each other.Through in-depth research on these interactions,strong coupling between the optical field and mechanical resonator can be achieved,and this strong coupling can be used to achieve frontier applications,such as micro-mechanical mass spectrometers,optomechanical microwave resonator,photon-based quantum computing and communication,etc.The prerequisite for achieving these applications is that the mechanical resonator must be cooled to its quantum ground state.However,due to the noise interference from the external environment,the mechanical resonator cannot enter the quantum regime.The composite system of the coupled optical parametric amplifier provides a unique platform to solve the above problems.Based on the optical parametric amplifier,this thesis proposes two theoretical schemes for cooling mechanical oscillators.The specific research content is as follows:The problem of intracavity-squeezed cooling in an optical force system consisting of three cavity fields is investigated.By coupling an optical parametric amplifier in the optomechanical cavity,the optomechanical cavity is coupled to the same auxiliary dissipative cavity on both sides.Intracavity-squeezed causes destructive interference of quantum noise,and breaking the quantum backaction limit.By adjusting the squeezing parameter,the heating rate of the system can be completely suppressed and the optimal solution required for the cooling process can be obtained.In addition,the research shows that the ground-state cooling of the mechanical resonator has no strict requirement on the auxiliary cavity.Using the Fermi Golden Rule theory,an analytical expression for the final phonon number in the steady state is calculated.Finally,ground-state cooling in a three-cavity optomechanical system is discussed in detail.Even when the system is in the unresolved-sideband regime,the mechanical resonator can still achieve good cooling effect.This research can provide a reference value for the theoretical study of cooling macroscopic objects in multi-auxiliary cavity hybrid systems.This problem of cavity squeezed cooling in a double Laguerre-Gauss rotating cavity system is also studied.This scheme takes advantage of the unique properties of the double Laguerre-Gaussian cavity,where the cooling process of large-scale mechanical resonators can be greatly enhanced.In the weak coupling regime,the optical fluctuation spectrum of the system can be obtained by using the perturbation approximation method.At the same time,the incident pump laser drives the optical parametric amplifier coupled inside the cavity,thus producing a strong nonlinear squeezing effect that effectively suppresses the quantum backaction heating process,resulting in a significant improvement in the net cooling rate of the system.In addition,the effects of other physical parameters on the mechanical mode cooling are discussed.Finally,the steady-state phonon number of the system is studied,which can be less than1 in a large parameter range.Therefore,this scheme can effectively reduce the cooling limit of the mechanical mode.