Nonreciprocal Cooling And Squeezing In Spinning Optomechanical Systems

Optomechanical System(OMS)is a system to study the interaction between light radiation pressure and mechanical oscillation.Because it can be used to realize the coupling between different degrees of freedom and has many novel physical properties,it has been widely used in quantum optics and quantum information processing,such as optomechanically induced transparency,optomechanically induced absorption,optomechanically induced non-reciprocity,quantum squeezing and entanglement,and ground state cooling of mechanical oscillators.However,mechanical oscillator in practice is easily excited by environmental thermal excitation,then the mechanical oscillator must be cooled to the ground state in order to study the quantum effect of photomechanical system and apply it to quantum information processing.The ground state cooling of mechanical vibrators in the classical Fabry-Perot cavity is most widely studied,but the non-reciprocal ground state cooling and squeezing in the whispering-gallery mode have not been studied.To solve these problems,the nonreciprocal cooling and quantum squeezing of the cavity field of a mechanical oscillator embedded with optical parametric amplifier(OPA)in a spinning optomechanical system are studied.The system can achieve non-reciprocal transmission while suppressing thermal noise and compressed quantum noise.Recently,the realization of the quantum nonreciprocity,i.e.optomechanical entanglement,in the absence of any classical nonreciprocity has been proposed to protect quantum entanglement with nonreciprocal devices.Here we shall investigate the quantum nonreciprocities,including the nonreciprocal cooling and the nonreciprocal optical squeezing,even in the absence of classical nonreciprocity,and consider the transfer between the two kinds of nonreciprocities.(1)We study the nonreciprocal ground state cooling in a single whispering-gallery spinning optomechanical system.According to Sagnac-Fizeau,non-reciprocal ground state cooling is realized by driving the spinning whispering-gallery cavity from different directions.The ground state cooling effect of the mechanical oscillator becomes better with the increase of the OPA gain coefficient when the optical microcavity is fixed without rotation.When the optical cavity spins counterclockwise,the driving laser drives the system from the left and right sides respectively,realizing the non-reciprocal ground state cooling caused by the Sagnac effect.We also realize the transformation of classical non-reciprocity and quantum reciprocity by adjusting the detuning.Unfortunately,in the present system,classical reciprocity can be realized,meanwhile quantum non-reciprocity is difficult to appear because the mechanical mode is heated at this time.(2)We also study nonreciprocal quantum squeezing in a single whispering-gallery-mode spinning optomechanical system.By investigating the optical compression of optical cavity coupled optical parametric amplifier(OPA),we find that the optical field is further squeezed as the nonlinear gain coefficient of OPA increases.The optimal quantum squeezing decreases with the increase of optical parametric amplifier phase.The nonreciprocal quantum squeezing is realized in the present system,which comes from the Sagnac-Fizeau effect caused by the different rotation directions of the driving laser in the resonator.The modulation of quantum and classical non-reciprocal conversion is also realized by tuning the detuning.With the increase of the nonlinear gain coefficient of OPA,the phenomenon of light-induced amplification appears when the coupling coefficient of tunnel is fixed.(3)Finally,we study the backscattering caused by random defects in a two-mode whispering-gallery-mode spinning optomechanical system.It has been shown that part of the inhibition effect caused by backscattering can be offset when the cavity of the whispering-gallery-mode rotates.Then we study the influence of OPA on the average photon number.With the increase of the nonlinear gain coefficient of OPA,the phenomenon of light-induced amplification appears when the coupling coefficient of tunnel is fixed.When the nonlinear gain coefficient of OPA is fixed,with the increase of the tunneling coupling coefficient,positive scale splitting appears in the image,and the positive scale splitting behavior is gradually strengthened,and the optical force induced absorption valley is gradually enhanced and approaches zero.Since the whispering-gallery optical microcavity is easy to miniaturize and integrate,the non-reciprocal ground state cooling of mechanical oscillator and non-reciprocal quantum squeezing of cavity field studied in this paper have potential application value in practical integration in classical information processing and quantum information processing.