理论研究了频率非简并第I类自发参量下转换过程中产生的纠缠光子对的量子特性,且与频率简并的情况做了对比.通过纠缠光子对的联合谱强度分析了纠缠光子对的光谱特性及纠缠特性；通过洪-区-曼德尔干涉仪和马赫-曾德尔干涉仪分析了纠缠光子对的量子干涉特性.结果表明:脉冲泵浦作用下,由于频率非兼并使得相位匹配函数不对称,导致两纠缠光子可区分,量子干涉可见度减小.随着泵浦脉冲频宽的增加,这种效应更加明显.连续激光泵浦时,相位匹配函数是对称的,得到最大的纠缠度和量子干涉可见度.该研究为频率非简并纠缠光子源在各种量子信息方案中的应用提供理论指导.

The quantum properties of entangled biphotons generated via frequency-nondegenerate type-I Spontaneous Parametric Down-Conversion (SPDC) were studied in theory, and compared with that of frequency-degenerate type-I SPDC. The properties of spectrum and entanglement of entangled biphotons in both cases were analyzed by the joint spectral intensity; the property of quantum interference was given by the results of Hong-Ou-Mandel interferometer and Mach-Zehnder interferometer. The results show that, for pulse pumping, the phase-matching function is shown to be asymmetric as a result of frequency-nondegenerate, which leads to entangled biphotons distinguishable and quantum interference visibility was reduced. As the pump bandwidth is increased, this effect becomes more pronounced. For monochromatic pumping, the phase-matching function is shown to be symmetric, which results in maximum entanglement and quantum interference visibility. These results provide a theoretical basis for the applications of frequency-nondegenerate entangled photon source in various quantum information schemes.