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Low noise up-conversion single photon detector and its applications in quantum information systems

We developed low-noise up-conversion single photon detectors for 1310 nm based on a periodically-poled LiNbO3 (PPLN) waveguide. The low-noise feature is achieved by using a pulsed optical pump at a wavelength longer than the signal wavelength. The detectors were used in a quantum key distribution (QKD) systems based on polarization encoding, measurement for entangled photon pairs and spectrum measurement at single photon levels. In this paper, the overall detection efficiency and noise level of the detectors are characterized and the polarization and wavelength sensitivity of the detection efficiency is analyzed. The applications of this detector in quantum information systems are also described.