Ground State Cooling Of The Mechanical Oscillator In An Optomechanical Double-cavity

In recent years,the development of cavity quantum photomechanics has been very rapid,and has played a very important role in quantum information processing,quantum basic principle verification,and high-precision measurement.The ground state cooling of mechanical oscillators is one of the basic problems in cavity quantum photomechanics,and has attracted more and more attention.More and more researchers are interested in this question.The traditional method of cooling the ground state of a mechanical oscillator is distinguishable sideband cooling.This method must satisfy the frequency of the mechanical vibrator much larger than the dissipation rate of the light field.However,many standard optical cavity optical systems in experiments are difficult to achieve distinguishable Band conditions,therefore,the scientists have proposed many ground state cooling under indistinguishable sideband conditions.The so-called ground state cooling is to make the number of steady-state phonons of the mechanical oscillator less than one.Based on the optical pressure fluctuation spectrum and steady-state phonon number,based on the standard single-cavity optical system,this paper mainly studies the optical dual-cavity system under indistinguishable sideband conditions and the optical cavity system under the influence of atomic cavity Ground state cooling of mechanical oscillator.In chapter 1,we first introduced the research background of optomechanical cavity system,including the basic concepts of mechanical oscillators,optical microcavities,and radiation pressure.Second,we also gave the basic processes of ground-state cooling of electromagnetically induced transparency and mechanical oscillators.In Chapter 2,we first give the Hamiltonian of optomechanical double-cavity system,from which the Langevin equation is derived,and the optical pressure fluctuation spectrum,the cooling rate,and the number of steady-state phonons in the case of double-cavity coupling are also given.Itwas found that when the optimal parameter conditions are satisfied(the cooling transition rate of the mechanical oscillator corresponds to the maximum value of the optical pressure fluctuation spectrum,and the heating transition rate corresponds to the minimum value of the optical pressure fluctuation spectrum),the mechanical oscillator can be cooled to a steady state phonon Count enough.In Chapter 3,We focus on the ground state cooling of the mechanical oscillator under the influence of optomechanical double-atom-cavity.An ensemble of two-atoms are trapped into one optical cavity,and the standard optomechanical atom-cavity is formed.And the ground state cooling of a mechanical oscillator under the influence of the standard optomechanical atom-cavity is studied.Analogous to Chapter 2,the systems are given separately.Hamiltonian,Langevin equation,cooling rate and steady-state phonon number,we found that the effect of the atomic ensemble at this time is the same as that of the auxiliary optical cavity introduced in Chapter 2.The mechanical oscillator will be more cooled than the original one.The cooling is better than before.Based on this,we combined the two and study the effect of an atomic ensemble in the auxiliary cavity on the mechanical oscillator cooling,that is,the ground state cooling of the mechanical oscillator under the influence of optomechanical double-atom-cavity.By giving the Hamiltonian and Langevin equations,it is found that the cooling effect of the atomic cavity on the mechanical oscillator is not as good as when the atom and the optical cavity act independently,so it is not that the more complex the system,the better the cooling effect.We are looking for a more convenient model for ground state cooling of mechanical oscillators.Finally,the fourth chapter summarizes my research content and looks forward to future research work.