| Nowadays,information security has gradually become hot research that people focus on with the development of information technology.High-speed secure communication based on optical sources provides an important support for information security.Optical sources such as coherent light,squeezed light,and chaotic light can be generally used as carriers to transmit information,generate and distribute random keys,etc.The property and quality of optical sources directly affect communication security and rate.Therefore,characterization and evaluation of the light field and preparation of high-quality optical sources have become urgent issues in high-speed secure communication.So far,characterizations of the quality of optical sources have mainly focused on the research of macrodynamic and quantum statistics.As an important quantum resource,squeezed states are mainly studied for photon number distribution,phase-space distribution,and super-bunching.However,quantum properties such as the distribution reflected by higher-order photon correlation and anti-bunching still need to be studied.Squeezed states with continuously controllable high-order photon correlation properties also are urgent in new hybrid discrete-and continuous-variable quantum communications and precision measurement.Meanwhile,as another important optical source in high-speed secure communication,chaotic light was mainly concerned with macroscopic dynamics such as frequency spectrum,time sequences,bifurcation diagram,etc.And we also started to preliminary investigate quantum statistics such as photon number distribution and second-order photon correlation.The measurement accuracy of dynamic properties and sensitivity of control parameters are limited.The photon number distribution and quantum statistics of correlation ensure sufficient sensitivity with the single-photon level detection technology,but they focus on the intensity distributions of the light field.Wigner quasi-probability distribution function can indicate all the information in phase space and reveal evolution process of optical field.However,it still lacks research on phase space distribution and amplification effect of chaotic lasers.In response to above problems,the main contents of this thesis are as follows:（1）We analyzed higher-order coherence for phase-controllable squeezed coherent states under ideal conditions.A theoretical model for high-order coherence based on the double Hanbury Brown-Twiss（DHBT）scheme,which has four single-photon detector modules,has been established.The second-order,third-order,and fourth-order coherences of two squeezed coherent states,which have different operation orders of displacement and squeezing,are derived in an ideal case.The high-order coherence of this phase-controllable squeezing coherent state is studied and analyzed as a function of squeezing parameter r,displacementα,and squeezing phaseθ.The high-order coherence degree exhibits a 2π-periodic variation with the squeezing phaseθ.The antibunching effect of the squeezed coherent state can be obtained in a wide range ofα-r parameter space when squeezing phaseθ∈[0,π/2].Ideally,the minimum anti-bunching value is g（2）=4.006×10-4,g（3）=1.3594×10-4,g（4）=6.6352×10-5.High-order coherence of the phase-controllable squeezed coherent state can be continuously varied from anti-bunching effect to bunching effect and super-bunching effect by adjusting three parameters continuously.（2）The effects of background noise and detection efficiency on the statistical properties of phase-controllable squeezed coherent states are investigated.When the detection efficiencyη=0.1 and background noiseγ=10-6,the strong antibunching effect can still be observed,i.e.g（2）=0.1740,g（3）=0.0432,g（4）=0.0149.The results indicate that the antibunching effect of higher-order photon correlation has strong robustness to the experimental environment.With the variation of squeezing parameter and displacement,DHBT can still effectively measure the high-order coherence of phase-controlled squeezing coherent states that continuously change from antibunching(g（n）<1)effect to super-bunching effect(g（n）>n!).Meanwhile,the continuous transition from antibunching to bunching and super-bunching can be achieved by optimizing the parameters and adjusting the squeezing phase to change from 0 toπin feasible experimental conditions.In addition,the antibunching effect of the phase-controllable squeezed coherent state is studied as functions of the measured mean photon number<n>and the squeezing degree S.When the measured mean photon number is much less than 1 and the squeezing parameter is less than 10-4,a prominent photon anti-bunching effect of g（n）<<0.5 can still be obtained.The results show that the control of the squeezing phaseθcan be used to prepare the squeezed coherent state with obvious antibunching effect,which have potentially important applications in quantum metrology and secure communication.（3）The phase-space quasi-probability distributions of vacuum state,phase-modulated coherent state,and chaotic lights are experimentally studied.We theoretically derived the Wigner functions of thermal state,coherent state,squeezed state,and Fock state.A quantum tomography measurement setup is built based on balanced homodyne detection.Firstly,we reconstructed the Wigner functions of the vacuum state and coherent state.Vacuum state serves for normalization.Subsequently,Wigner functions of chaotic light with different optical feedback and different incident light intensities are reconstructed and experimentally obtained amplification effects compared to vacuum state.Chaotic states with different optical feedback show different phase-space quasi-probability distributions,and it provides an experimental basis and guidance for further characterizing and distinguishing the phase-space distribution of the optical fields. |
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