Optomechanical Nonlinearity And Its Manipulation In Cavity QED System

Cavity optomechanics is a hot research field to explore the nonlinear photon-phonon interaction,and has become an important platform for manipulating the Bose field at the quantum level.However,the real single-photon strong coupling mechanism is still full of experimental challenges.This limits the generation of abundant non-classical effects in the single-photon strong coupling mechanism.Moreover,in order to explore more abundant physical phenomena and develop new quantum technologies,the hybrid cavity optomechanical system will be more promising.Cavity quantum electrodynamics(cavity QED)studies the interaction between matter localized in a specific space and the Bose field.But the cross study of cavity optomechanics and cavity quantum electrodynamics is still lack of exploration.The integration of cavity optomechanics and cavity quantum electrodynamics will greatly promote the development of each other.In this doctoral thesis,we mainly study the optomechanical nonlinearity and its manipulation on cavity QED system.The main contents are as follows:1.We proposed an all-optical scheme for the generation of squeezed Schrodinger-cat state,as well as studied the application of squeezed Schrodinger-cat state to phase evaluation.Our system is based on the Fredkin-type interaction between three optical modes,where the target mode is two-photon driven and the other two modes are coherent driven.We showed that by controlling the driving field of the system,our system can describe a degenerate three-wave mixing process and can lead to a two-photon loss of the target mode,thus determinedly placing the target mode in a squeezed Schrodinger-cat state.Meanwhile,our all-optical system can simulate cavity optomechanics with controllable squeezing under the ultrastrong coupling mechanism.In addition,we evaluated the phase in the optical interferometer by using squeezed Schrodinger-cat states.We showed that the quantum Fischer information of the phase can reach the Heisenberg limit in the large photon number limit,and that it can be an order of magnitude factor improvement over the Heisenberg limit in the low photon number limit.This is very advantageous for fragile systems that cannot withstand multiple photons.2.We proposed a double Laguerre-Gaussian(LG)rotating cavity optomechanical system and investigated the propagation properties of the probe field and its potential applications.In our system,the input lasers are all LG beams,in which one cavity is driven by a strong driving field and detected by a weak probe field,while the other cavity is driven by another driving field.Compared with the traditional single LG rotating cavity optomechanical system,we found that the effective cavity field detuning of the double LG rotating cavity optomechanical system simultaneously depends on the amplitude and sign of the orbital angular momentum carried by the beams.At the same time,an asymmetric transparent window can appear in the transmission spectrum of the probe field in the double LG rotating cavity optomechanical system.Specifically,for the orbital angular momentum with different amplitudes,the transmission spectrum of the probe field shows an obvious spectral shift,and the spectral shift has directionality for different signs of orbital angular momentum.Therefore,based on the spectral shift characteristics,we can simultaneously distinguish the amplitude and sign of the orbital angular momentum carried by the beams,so that we can judge the quality of the spiral phase plates.3.We studied the manipulation of entanglement in the Rabi model by quadratic optomechanical coupling,as well as analyzed the protection of entanglement by quadratic optomechanical coupling in an open system.In our system,the two-level system is coupled with the mechanical oscillator to form the Rabi model,and the mechanical oscillator is coupled with the auxiliary optical field through the quadratic optomechanical interaction.We showed that our system can be equivalent to the Rabi model depending on the photon number of the optical field.In the equivalent Rabi model,we found that the entanglement between the mechanical oscillator and the two-level system is controlled by the number of photons.Specifically,we can achieve strong entanglement between the mechanical oscillator and the two-level system and keep it unchanged during the evolution.We can also adjust the entanglement at a specific moment to achieve entanglement switching.Furthermore,when environment-induced decoherence and dissipation are considered,we found that they can be mitigated by increasing the number of photons in the auxiliary light field.4.We studied the manipulation of spin squeezing in the Dicke model by quadratic optomechanical coupling,as well as analyzed the evolution of spin squeezing in an open system.In our system,multiple two-level systems are coupled with the mechanical oscillator to form the Dicke model,and the mechanical oscillator is coupled with the auxiliary optical field through the quadratic optomechanical interaction.We showed that our system can be equivalent to the Dicke model depending on the photon number of the optical field.In the equivalent Dicke model,we found that the squeezing of the mechanical oscillator triggered by the photon number can be completely transferred to the two-level system.In addition,pairwise entanglement exists between two-level systems if and only if spin squeezing is present.Importantly,when considering the influence of the environment,our system can achieve a better squeezing degree than the optimal degree of spin squeezing achieved by the traditional Dicke model.