A high visibility Hong-Ou-Mandel interference via a time-resolved   coincidence measurement
  We report on the observation of a high visibility Hong-Ou-Mandel interference of two heralded photons emitted from a spontaneous parametric down conversion~(SPDC) pumped by continuous-wave~(cw) light. A non-degenerate photon pair at 1541~nm and 1580~nm is generated by cw-pumped SPDC through a periodically poled lithium niobate waveguide. The heralded single photon at 1541~nm is prepared by the detection of the photon at 1580~nm. We performed the experiment of the Hong-Ou-Mandel interference between heralded single photons in separated time bins and observed a high visibility interference. All detectors we used are superconducting nanowire single-photon detectors and an overall temporal resolution of the photon detection is estimated as 85 ps, which is sufficiently shorter than the coherence time of the heralded photons. 
Yoshiaki Tsujimoto, Yukihiro Sugiura, Motoki Tanaka, Rikizo Ikuta,   Shigehito Miki, Taro Yamashita, Hirotaka Terai, Mikio F...
quant-ph