We present a theory for quantum interference of four photons generated by spontaneous parametric downconversion. Detailed investigation of the dependence of fourfold coincidence count rate on time delay between the in...We present a theory for quantum interference of four photons generated by spontaneous parametric downconversion. Detailed investigation of the dependence of fourfold coincidence count rate on time delay between the incident and the reflective pump laser pulses is carried out. Gaussian type dependence is found, and good agreement between our theoretical results and experimental data reported in the literature is achieved.展开更多
We examine the intensity correlation functions of the two fluorescent fields that are emitted from the top and middle states of a doubly driven three-level atom in the cascade configuration. Novel interference effects...We examine the intensity correlation functions of the two fluorescent fields that are emitted from the top and middle states of a doubly driven three-level atom in the cascade configuration. Novel interference effects are shown. （i） Both of the fluorescent fields have anticorrelations which can exist for long times when the applied fields are on the two-photon resonance and far off one.photon resonances. （ii） Both of the fluorescent fields have strong correlations when the applied fields are far off one- and two-photon resonances. In particular, the extremely strong correlation occurs for the photons emitted from the top state. The above phenomena are traced to the multiple interference mechanisms.展开更多
The cavity-enhanced spontaneous parametric down-conversion far below threshold can be used to generate a narrow-band photon pair efficiently. Previous experiments on the cavity-enhanced spontaneous parametric down- co...The cavity-enhanced spontaneous parametric down-conversion far below threshold can be used to generate a narrow-band photon pair efficiently. Previous experiments on the cavity-enhanced spontaneous parametric down- conversion almost always utilize continuous wave pump light, but the pulse pumped case is rarely reported. One disadvantage of the continuous wave case is that the photon pair is produced randomly within the coherence time of the pump, which limits its application in the quantum information realm. However, a pulse pump can help to solve this problem. In this paper, we theoretically analyze pulse pumped cavity-enhanced spontaneous parametric down- conversion in detail and show how the pump pulse affects the multi-photon interference visibility, two-photon waveform, joint spectrum and spectral brightness.展开更多
We present the phase control of photon correlations in a driven four-level system in the double lambda configuration. The strong correlation and the anticorrelation are. obtained when the collective phase of four appl...We present the phase control of photon correlations in a driven four-level system in the double lambda configuration. The strong correlation and the anticorrelation are. obtained when the collective phase of four applied laser fields is varied. The coherent control is based on the phase-dependent coherent population trapping （CPT）. The strong correlation occurs when the system operates near CPT, while the anticorrelation occurs when the system is far away from CPT.展开更多
文摘We present a theory for quantum interference of four photons generated by spontaneous parametric downconversion. Detailed investigation of the dependence of fourfold coincidence count rate on time delay between the incident and the reflective pump laser pulses is carried out. Gaussian type dependence is found, and good agreement between our theoretical results and experimental data reported in the literature is achieved.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60378008 and 10574052.
文摘We examine the intensity correlation functions of the two fluorescent fields that are emitted from the top and middle states of a doubly driven three-level atom in the cascade configuration. Novel interference effects are shown. （i） Both of the fluorescent fields have anticorrelations which can exist for long times when the applied fields are on the two-photon resonance and far off one.photon resonances. （ii） Both of the fluorescent fields have strong correlations when the applied fields are far off one- and two-photon resonances. In particular, the extremely strong correlation occurs for the photons emitted from the top state. The above phenomena are traced to the multiple interference mechanisms.
基金supported by the National Natural Science Foundation of China(Grant No.10874171)the National Basic Research Program of China(Grant No.2009CB929601)+1 种基金the Innovation Fund from Chinese Academy of Sciencesthe Program for New Century Excellent Talents in University of China(Grant No.NCET-07-0791)
文摘The cavity-enhanced spontaneous parametric down-conversion far below threshold can be used to generate a narrow-band photon pair efficiently. Previous experiments on the cavity-enhanced spontaneous parametric down- conversion almost always utilize continuous wave pump light, but the pulse pumped case is rarely reported. One disadvantage of the continuous wave case is that the photon pair is produced randomly within the coherence time of the pump, which limits its application in the quantum information realm. However, a pulse pump can help to solve this problem. In this paper, we theoretically analyze pulse pumped cavity-enhanced spontaneous parametric down- conversion in detail and show how the pump pulse affects the multi-photon interference visibility, two-photon waveform, joint spectrum and spectral brightness.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10574052 and 60778005.
文摘We present the phase control of photon correlations in a driven four-level system in the double lambda configuration. The strong correlation and the anticorrelation are. obtained when the collective phase of four applied laser fields is varied. The coherent control is based on the phase-dependent coherent population trapping （CPT）. The strong correlation occurs when the system operates near CPT, while the anticorrelation occurs when the system is far away from CPT.
