Decay Process Of Single Photon In Optomechanical System

Optomechanics is a rapidly developing research field.In a simple optomechanical system,mechanical vibration mode is coupled to optical cavity mode through radiation pressure.One end of the optical cavity is fixed,and the other end is attached to the moving mechanical element.The displacement of the mechanical resonator is affected by the driving force of the optical field,that is,the incident light of the optical cavity will transfer the action of the force to the mechanical resonator through the way of radiation pressure to make it produce displacement.At the same time,the mechanical resonator can also control the frequency of the optical field by changing the length of the optical cavity.Starting from the microscopic derivation of the master equation,the paper has studied the attenuation process of single photon in the optomechanical system(decay process of excited state and quantum decoherence).Compared with the master equation commonly used in quantum optics,the microscopic derivation of the master equation can describe the decay process of the energy eigenstate,so as to more accurately deal with the problems related to the decay process and describe the decay process of the physical system studied in a more detailed and accurate way.In this paper,the single photon attenuation process of an ultra-strong coupled region in optomechanical system is studied:(1)Spontaneous emission is the spontaneous transition of photons from high excited state to low excited state or ground state.In the process of single-photon spontaneous emission,the calculated results of the mean number of photons in the cavity mode show that the attenuation process of the energy excited state of the optomechanical system affects the process of single-photon spontaneous emission jointly according to the superposition of statistical weight,and the statistical weight depends on the strength of the optomechanical coupling.(2)The superposition of quantum states is the core of quantum theory and is generally regarded as the mark to distinguish the quantum world from the classical world.Superposition states are coherent with each other,but over time,this coherence will slowly disappear,known as quantum decoherence.Quantum decoherence is inevitable,and there are many factors leading todecoherence.The calculations of the non-diagonal matrix elements of the optical cavity in this paper show that the quantum decoherence of the optical cavity is dominated by the decay process of the excited energy state.The attenuation of coherence presents the oscillation law of sine-cosine curve on the whole,and the attenuation speed and amplitude of coherence are affected by the photomechanical coupling strength.The larger the coupling strength is,the faster the coherence disappears.In other words,the smaller the coupling strength is,the better the quantum coherence is preserved.In addition,the microscopic derivation of the master equation is also applicable to the discussion of other related problems in ultra-strong coupled optomechanical systems.