Nonlinear Effects In Atom-cavity Coupling System And Its Application

In recent years,with the development of quantum information technology,people have gradually deepened the study of light,a quantum information transmission and processing carrier.However,due to the limitation of the reason that photons are not easily coupled and the speed of light is fast,light cannot store quantum information.The coherent interaction between the light and the atoms provides a feasible way to realize the transmission between the light field and the quantum state of the real particle.In particular,based on the atomic coherence effect of electromagnetically induced transparency?EIT?,a series of studies derived from it will have important implications for the development of quantum communication,quantum computing,and quantum information control.The coherent interaction between light and atoms will produce different properties based on different conditions,and the combination of atoms and cavities can greatly enhance the coupling strength between the light field and the physical particles,providing a new platform for studying this property.Most of the thermal atom-cavity coupling systems are based on the coupling of helium-type EIT atoms to an annular cavity system.In this paper,the four-wave mixing?FWM?effect of a three-level EIT atom ring cavity coupled system based on a standing wave field is studied.Mainly divided into three parts,the content is as follows:Firstly,the principle and application of the related quantum effect in this coupling system are introduced.Part 2:Theoretically,the Hamiltonian and density matrix equations of the?-type EIT atom system are acted on by the two-color coupling field,and the transmission spectrum of the atom cavity,the FWM effect,and the double-darkness phenomenon are analyzed.Part 3:The FWM effect in the?-type three-energy annular cavity system was experimentally studied.The variation of a series of experimental parameters,such as coupling optical power,particle number density,and coupled light detuning,is discussed.Experimental measurements show that the reflected signal exhibits an asymmetrical bimodal structure at the center of the atomic resonance frequency,while the reflected signal at the coupled optical mismatch shows a single-peak spectrum that is sensitive to the detuning of the cavity mode.This phenomenon occurs mainly in the center of the atomic resonance frequency.When the FWM signal passes through the cavity medium in the reverse direction through the cavity mirror,the strong absorption effect generated by the standing wave field driving the cavity atoms also applies to the FWM signal^[34],thereby weakening the reflected signal.However,resonance cannot be formed in the cavity.In contrast,in the single-photon detuning condition,due to the Doppler shift effect,the strong absorption of the FWM signal by the inner cavity medium is severely suppressed,thereby exhibiting resonance and narrowing the line width.The four-wave mixing signal of the cavity.The discovery of this experimental phenomenon has provided conditions for the preparation of the entangled coherent light field near the atomic resonance and the realization of the all-optical control of the quantum logic gate operation.Part 4:Based on the above experimental research,by changing the interaction length of the inner cavity medium and controlling the particle number density and the interaction strength of the coupling field,experiments have been carried out to achieve the center of the atom resonance frequency and the single dark state of the inner cavity of the cavity.The conversion of the dark state peaks;and further analysis and study of the changes in the temperature,coupled optical power,coupled optical frequency detuning,etc.of the double dark state peaks;and on this basis,the acousto-optic modulator drives the reverse coupling field.Opening and closing,the experiment designed a three-channel composite logic light switch.