Applications And Statistical Properties Of Single Photon Pairs Generated By SPDC Process

Spontaneous Parametric Down Conversion (SPDC) process was realized using the second-ordered nonlinear effect of the crystal. In the condition of phase matching, a pump photon with high frequency was divided into two photons with lower frequency, and these twin photons have high correlations in time, space and energy. Up to now, SPDC was considered as one of the most effective ways to generate the single photon pair with high correlations, and the single photon state was used widely in basic quantum optics experimental researches, quantum key distribution and quantum calculating as a nonclassical field.Since SPDC was observed in the experiments, the photon pairs generated by it were widely investigated. Particularly, we could obtain a single photon by detecting the one of the twin photon, that's to say, we can predict the existence of a single photon without destroying it. Due to the special advantages of the SPDC, the researches in this paper are based on SPDC processes, combining the technology of single photon detecting, coincidence counting and photocounting statistics technology.The main research points of this paper are as follows:1.Parts of the ways to generate the single photon were reviewed and the advantages of SPDC were given. Then the applications of SPDC in the region of basic quantum theory researching, quantum calculating, and the quantum metrology were given.2.Based on the phase matching conditions, the distribution range and coincidence range of the signal and idler generated by SPDC were theoretically analyzed, when a CW wave and a femto-second pulse was used as the pump source of SPDC.The results showed that the angel distribution range of signal is wider when the femto-second pulse used as the pump because it has wide spectrum, and wider the spectrum, wider the distribution range of signal.Finally, the experimental results confirmed the analyses about the angel distribution of the signal, when femto-second pulse was used as the pump source of SPDC.3.The influences of detection bandwidth on the quantum ghost imaging were analyzed when a femto-second pulse was used as the pump of a type-I SPDC.The results showed that the detection bandwidth would limit the range of imaging, but would improve the visibility of ghost image.And, the line shape of the filter would influence the ghost imaging. Finally, a normalization process was shown to eliminate these influences.4. A theoretical scheme about a stimulated emission-based detector was proposed using the SPDC processes.And the antinormally ordered second order correlation and Fano factor were analyzed using such detector. The results were compared with the normal detector and the advantages of stimulated emission based detector were given.Finally, the theoretical scheme is confirmed in the experiments and the results matched with theoretic qualitatively.5.The photocounting statistic distribution of SPDC and a weak pseudo-thermal field was investigated. We found that the statistical distribution continues to be well described by the negative binomial function. However, the degeneracy factor in the distribution is observed to be markedly different from the conventional value. The Mandel theory is reexamined, and quantum fluctuation of light intensity is determined to be the source of this discrepancy. Finally, the theoretic was confirmed by the experiments.The creative works are as follows:1.The influence of femto-second pulse as the pump source of SPDC to the distribution range and coincidence range of signal and idler is analyzed, and the experimental results matched with the theoretical results.2.The influence of detection bandwidth to the ghost imaging process was investigated, and the ways to eliminate such influences were given.3.A theoretical scheme about the stimulated emission-based detector was proposed using the SPDC processes, and the applications of such detector in antinormally ordered second order correlations and Fano factor were investigated.4.The Mandel theory was reexamined, and a new quantum expression for the degeneracy parameter in photocounting statistics distribution for thermal field was given. And it was confirmed a correct expression by the experiments.