Tsujimoto Yoshiaki, Sugiura Yukihiro, Tanaka Motoki, Ikuta Rikizo, Miki Shigehito, Yamashita Taro, Terai Hirotaka, Fujiwara Mikio, Yamamoto Takashi, Koashi Masato, Sasaki Masahide, Imoto Nobuyuki
Opt Express. 2017 May 29;25(11):12069-12080. doi: 10.1364/OE.25.012069.
A high visibility Hong-Ou-Mandel (HOM) interference between two independently prepared photons plays an important role in various photonic quantum information processing. In a standard HOM experiment using photons generated by pulse-pumped spontaneous parametric down conversion (SPDC), larger detection time windows than the coherence time of photons have been employed for measuring the HOM visibility and/or drawing the HOM dip. If large amounts of stray photons continuously exist within the detection time windows, employing small detection time windows is favorable for reducing the effect of background noises. Especially, such a setup is helpful for the HOM experiment using continuous wave (cw)-pumped SPDC and the time-resolved coincidence measurement. Here we argue that the method for determining the HOM visibility used in the previous cw experiments tends to suffer from distortion arising from biased contribution of the background noises. We then present a new method with unbiased treatment of the cw backgrounds. By using this method, we experimentally demonstrate a high visibility HOM interference of two heralded telecom photons independently generated by SPDC with employing cw pump light. An observed HOM visibility is 0.87 ± 0.04, which is as high as those observed by using pulse-pumped SPDC photons.
两个独立制备的光子之间的高可见度Hong-Ou-Mandel（HOM）干涉在各种光子量子信息处理中起着重要作用。在使用脉冲泵浦自发参量下转换（SPDC）产生的光子进行的标准HOM实验中，用于测量HOM可见度和/或绘制HOM凹陷的检测时间窗口比光子的相干时间大。如果在检测时间窗口内持续存在大量杂散光子，采用小的检测时间窗口有利于降低背景噪声的影响。特别是，这种设置有助于使用连续波（cw）泵浦SPDC和时间分辨符合测量的HOM实验。在这里，我们认为先前的连续波实验中用于确定HOM可见度的方法往往会受到背景噪声偏差贡献引起的失真影响。然后，我们提出了一种对连续波背景进行无偏处理的新方法。通过使用这种方法，我们通过实验证明了在使用连续波泵浦光的情况下，由SPDC独立产生的两个预示电信光子的高可见度HOM干涉。观察到的HOM可见度为0.87±0.04，与使用脉冲泵浦SPDC光子观察到的可见度一样高。
