Fig. 4: Time-energy entangled photon pair. | Light: Science & Applications

Fig. 4: Time-energy entangled photon pair.

From: InGaP χ(2) integrated photonics platform for broadband, ultra-efficient nonlinear conversion and entangled photon generation

Fig. 4

a Schematic of the measurement of the time-energy entanglement of the SPDC photons. VOA: variable optical attenuator. FPC: fiber polarization controller. b Two-photon time difference histogram. The binwidth is 10 ps. The middle peak corresponds to the time-energy entangled state. c Coincidence counts in 800 ps binwidth integrated in 15 s of the SPDC photon pair for various interferometer phases (red) and the interference fringe of a CW laser (blue). Solid lines are sinusoidal function fitting. Error bars represent the shot noise. d Counts in 5 ms of SPDC photons in one SNSPD

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