Single Photon Detection In Quantum Key Distribution

Quantum information is a new theory based on quantum mechanics. The development and application of quantum information will have deep influence upon our society. In this theory, the quantum key distribution (QKD) is the most hopeful to be realized, however, the technology of single-photon detection is the key to make QKD into reality. It's important to the QKD and even to the quantum information.The main work in this thesis is the theory and experiment of single-photon detection(SPD), including the project and experiment of QKD, the theory of photoelectricity and the selection of detector, the performance of detector, the calibration of quantum efficiency, the circuit of single-photon detector, the information reconciliation and privacy amplification. Significant work are shown below:1. Present the history of cryptography and the protocol of QKD. Using simple and practical system, we realize the BB84 protocol and B92 protocol of QKD. There are high bit rate and low error rate in our experiment.2. Studying the noise of detector and the measurement of its main performance, a simplified absolute self-calibration project of SPD's quantum efficiency is given. This project is more simple, and can automatic process the repetition measurement and data analysis by computer..3. Give the avalanche photon detector's control circuit and other circuit, including the short differential pulse cancelling circuit, the balance circuit, the coincidence measurement, and the cooling way. A single photon detection system is designed. This system has good performance in low frequency(MHz).4. Using high speed DAQ(data acquisition) card, it is realized by program that the random number is generated and sent from sender(Alice) and the data analysis of single-photon detection in receiver(Bob). And then the key is generated from communication in normal channel. Cascade protocol and BICONF protocal on the information reconcilation are used to reduce the error rate to near zero.