Qi Wen-Rong, Liu Rui, Kong Ling-Jun, Wang Zhou-Xiang, Huang Shuang-Yin, Tu Chenghou, Li Yongnan, Wang Hui-Tian
Opt Lett. 2020 Feb 1;45(3):682-685. doi: 10.1364/OL.384363.
Phase memory is an effect in which the interaction between a coherent pump beam and a nonlinear crystal generates photon pairs via the spontaneous parametric down-conversion process, then the down-converted photons (signal and idler) can carry the phase information of the pump beam. There has been much research on the memory of the dynamic phase so far; however, there is no report on the memory of non-dynamic phase, to the best of our knowledge. Here we acquire a Pancharatnam-Berry (PB) geometric phase in a physical system when light travels along a trajectory in polarization-state space. Induced coherence occurs in a cascaded scheme composed of two nonlinear crystals, when the idler photons in both crystals are aligned to be indistinguishable. A NOON ($N; = ;{2}$N=2) state is established when blocking the two idler photons. We explore the PB geometric phase memory of the NOON state and induced coherence. We find that the first-order interference of the two-photon state or signal photons can be controlled by introducing the PB geometric phase to the pump light. This may facilitate precise control of the phase of the down-converted photons.
相位记忆是一种效应，即相干泵浦光束与非线性晶体之间的相互作用通过自发参量下转换过程产生光子对，然后下转换光子（信号光子和闲频光子）可以携带泵浦光束的相位信息。到目前为止，已经对动态相位的记忆进行了大量研究；然而，据我们所知，尚无关于非动态相位记忆的报道。在这里，当光在偏振态空间中沿着一条轨迹传播时，我们在一个物理系统中获得了潘查拉特纳姆 - 贝里（PB）几何相位。当两个晶体中的闲频光子被调整为不可区分时，在由两个非线性晶体组成的级联方案中会发生诱导相干。当阻挡两个闲频光子时，会建立一个NOON（$N = 2$）态。我们探索了NOON态和诱导相干的PB几何相位记忆。我们发现，通过将PB几何相位引入泵浦光，可以控制双光子态或信号光子的一阶干涉。这可能有助于精确控制下转换光子的相位。
