泵浦光强度对纠缠光子品质的影响

纠缠源亮度和品质直接决定其作为量子信息处理资源的应用价值，研究参量转换过程中纠缠对的产生效率和品质随泵浦激光强度的变化关系对制备高品质纠缠源具有基础意义．利用参量下转换、极化后选择和符合计数技术，制备了Einstein-Podolsky-Rosen (EPR)偏振纠缠态．研究了泵浦激光强度对纠缠光子产生效率、对比度和保真度的影响．结果表明，随泵浦激光强度增大，纠缠对产生效率保持不变，也即纠缠源亮度随激光强度增大而线性增大；纠缠光子的对比度、保真度随激光功率增大而下降．

Effect of pump intensity on quality of entangled photons

The brightness and quality directly determine the application value of entangled photons as resource of quantum information processing. In parametric conversion process, study on the relation between pump laser intensity and the produce efficiency and quality of entangled photons has basic significance to the preparation of high quality entanglement source. Using spontaneous parametric down conversion, the polarization post selection and the technique of coincidence counting, polarization EPR entangled states has been prepared. Effect of the pump laser intensity on efficiency, contrast, and fidelity of the entangled photons has been studied systematically. The results show that with the increase of the pump laser intensity, the generation efficiency of entangled photons is almost invariable, namely the entanglement source brightness increases linearly with the laser intensity. On the other hand, the contrast, fidelity of entangled photons decreased with the increment of laser power.