1550nm Single-photon Detection And Its Applications

Quantum cryptosystem is a novel cryptosystem, which uses a single photon as the information carrier. The absolute security of the quantum cryptosystem is guaranteed by the quantum mechanics. One of the major parts in quantum cryptosystem is the single photon detector. In quantum cryptosystem, the communication distance of the system and quantum bit error rate are mainly laid on the performance of the single-photon detector. Therefore, the key problem in quantum cryptosystem is how to improve the quantum efficiency and how to decrease the dark-count probability.There are three main jobs in this paper.First, we discuss some key techniques in the single-photon detection, which include the dual-gate technique, the spike-cancellation using another avalanche photodiode and the spike-cancellation using an adjustable capacitance.Second, we introduce our two single-photon detectors, and compare the performance of the single-photon detector with the ID200 single-photon detector of idQuantique company which is the best single-photon detector in the world.Third, we apply our single-photon detector at 1550nm in the 50.6km long distance stable quantum key distribution system. And according to the result of a simulate experiment, we prove that this single-photon detector can be used in the differential phase shift quantum key distribution system with expansible setup, which is first proposed by us. At last, we demonstrate a quantum key distribution with polarization code at 1550 nm in long-distance single-mode fiber using four SPD2 single-photon detectors.