Optimization And Manipulation On Atom-light Hybrid Interference

In the past decades,the research on the interaction between light and atomic ensemble has attracted extensive attentions,and many techniques for precise control of quantum states based on the interaction of light and atoms have been produced,which has promoted the de-velopment of quantum precision measurement.Based on the Stimulated Raman Scattering(SRS)process in the atomic ensemble,this thesis carefully explores the establishment pro-cess of SRS in atomic ensemble and verifies the existence of slow-light effect in the SRS.In addition,the temporal mode of the optical field in the SRS is optimized and manipulated by the quantum control technology,which reduces the mode mismatch noise in the process of light-atom interaction and enhances the correlation between light and atoms.Based on above research,the coupling strength in the interaction process of light and atoms can be optimized and manipulated to reduce the influence of loss on the signal-to-noise ratio(SNR)of SU(1,1)type atom-light hybrid interferometers,and then the performance of the interferometer can be improved.The specific research contents are as follows.1.The establishment process of SRS is introduced in detail theoretically,and the slow light effect existing in the process of SRS is analyzed.The delay effect is demonstrated ex-perimentally,and relationship between the peak-peak delay time and parameters of seed and the amplified Stokes field under different gain conditions is verified experimentally.Based on the linear dependence between photon number and delay time,the intensity of input optical field can be measured by delay time in principle.2.The correlation between Stokes field and atomic spin waves is improved when the SRS process is optimized.An optimization method is proposed in the experiment,which is to find the first order temporal mode of the Stokes field through iterative optimization of the seed waveform,which can reduce the noise caused by the multi mode mismatch during the SRS process.This method reduces the noise of Stokes field and enhance the intensity correlation between Stokes and atomic spin wave,and lays a foundation for optimizing the beam splitting process and improving the SNR of the atom-light hybrid interferometer.3.Taking the low-noise SRS process as the beam splitting and combining process to construct an atom-light hybrid interferometer,and the signal to noise ratio(SNR)of the inter-ferometer is optimized.Firstly,the relationship between SNR and internal loss of the SU(1,1)type atom-light hybrid interferometer is analyzed in detail,and it's found that the SNR de-creases with the internal loss.The influence of internal loss on SNR can be effectively reduced by adjusting the coupling coefficient of light and atom interaction during the beam combining process of the interferometer to meet the optimization condition.Further research shows that the optimum conditions of the visibility of the interferometer are exactly the same as those of SNR.In practical applications,the visibility can be used as a criterion for judging whether the interaction coupling coefficient is optimal in the beam combining process,and then the best SNR can be easily obtained with the presence of loss.Finally,the experiment demonstrates the visibility optimization of the interferometer,which restores the visibility from 53% to 88%even the optical field arm loss reaches 96%.