| Secure communication plays a pivotal role in human life, especially in the field of national defense and military. However, with the development of the quantum algorithms and the quantum computer, the classical cryptosystem, which is based on complexity of computation, is confronting with some serious challenges. While the uncertainty principle of quantum mechanics provides us with a method to find out eavesdropping proactively, which eliminate the possibility of the existence of illegal wiretapping fundamentally. This method is Quantum Combination, and is commonly referred to as Quantum Key Distribution (QKD).Currently, quantum key distribution technology is developing in the direction of experimental and practical applications. Meanwhile, the complexity of the actual environment has put higher requirements for the reliability of the QKD system. This thesis is mainly to do research to achieve a reliable QKD system.First, we build the implementation model of the reliable QKD system, which is based on BB84protocol and decoy-state laser source, and designed two PCBs: FPGA-based main control board(MCB) and high voltage-and-delay board(HVDB). Furthermore, we proposed a new synchronization scheme.Second, we designed a set of FPGA logic, which controls the QKD process. In our solution, basis sifting, key reconciliation and privacy amplification are all implemented within a FPGA.Third, propose optimization algorithms to shorten the Start-up time of the QKD system, which effectively increased the performance of the system.Through a long time stress test in Hefei Metro experiments network of quantum communication, the reliability of our system has been verified. With a transmission distance of25Km and the total path attenuation of13dB,thefinalkey generation rate reaches5Kbps,and the error rate is less than2%.All of these make quantum communication a significant step forward in the direction of industrial applications, and laid solid foundation for practical QKD network in the future. |
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