The Study Of Data Processing Algorithm In Ground-satellite Quantum Communication Experiment

Quantum information is an interdisciplinary which combines quantum mechanics andclassical information science. Quantum communication is the most rapidly developing fieldtowards practical quantum information during the past three decades and makes photon as carrierfor message, thus it has unique advantages of absolute security. Quantum communication providesthe solutions for current information security.Quantum communication chiefly include two phase. One is the experiment of distribution,and another is the data processing. The first is to accomplish the transmission of information byquantum encoding and the later is to obtain the final quantum key sequence by quantumcommunication algorithm.This dissertation carries out the research on the theory and key technologies of data post-processing algorithm in the free-space quantum key distribution. First of all, we introduce the timesynchronization algorithm based on synchronous light, and then propose a synchronizationalgorithm based on GPS and according to the correlation of continuous time, we can rapidlyimplement time synchronization, and run the basis verification, reconciliation and privacyamplification and gain the absolute security key sequence. On this basis, we develop a set ofquantum key distribution system and tracking system software, and accomplish the realization oftracking algorithm and optimization algorithm. We verify the performance of the system and thefeasibility of the data post-processing algorithms according to Qinghai Lake52km free-spacedecoy state quantum key distribution in daylight and its success provides theoretical basis forground-satellite quantum key distribution in the daylight and at night. Certainly the quantumcommunication algorithm with sifting the effective time span algorithm and time windowalgorithm overcome the fluctuation influence of link efficiency. The result of the experiment is thatthe error rate of the signal state is1.78%and final key rate is123bps, which provides theory basisin ground-satellite quantum key distribution in daylight and at night. At last, we analysis theinfluence of the relative distance between satellite and ground-station for data post-processing, andthe low limitation of the key generation rate towards single link or composite link, and at the sametime we chose the experimental data of8km and40km to simulate the composite link between ground and satellite and the final key rate is86bps. We likely to confirm the feasibility of decoyquantum key distribution based on satellite relay via theoretical analysis and numerical calculation.