The Design Of Quantum Key Distribution Broadband Electronic Control System

With the development of computer technology, the modern cryptography whose security based on the scale of problem solving encountered more and more severe tests.Although the one-time pad encryption algorithm can guarantee the absolute security of information, how to distribute and manage large-scale key has greatly limited of its application. Quantum Key Distribution(QKD) solved the problem of key distribution over long distances due to the physical property of quantum. QKD system consists of QKD physical system, QKD electronic control system, QKD post-processing system and application software. Different QKD physical system owns its own style of quantum preparation, transmission and measurement which results in the existing control system can not adapt to the new QKD physical system.In order to improve the QKD electronic control system’s adaptation ability for the QKD physical system, this dissertation proposed a broadband electronic control system for the dual-way Faraday-Michelson based physical system. The main work of this dissertation are introduced below:A kind of software and FPGA combined QKD broadband electronic control system scheme for the broadband control problem of the dual-way QKD physical system is proposed in this dissertation. This architecture was divided into two different parts to improve the electronic control system’s adaptation ability and stability. One for control signal generation and the other part is responsible for signal parameters setting. This architecture greatly solved the controlling problem that the dual-way Faraday-Michelson based QKD physical system faced in different communication condition.An special counter based control signal generation scheme was proposed to meet the target physical system’s requirement of control signal whose frequency adjustment range is wide and whose adjustment precision is high. This scheme received a good quality of control signal under the high frequency work clock by the carefully designed high frequency digital circuit. In order to solve the control signal interrupted problem which is brought by the mismatching speed between the phase modulator(PM)voltage data generation and the PM control signal generation, the pipeline based PM voltage data generation scheme and PM control signal generation scheme were designed. The test result proves that the proposed special counter scheme and the pipeline design scheme can meet the real physical system’s requirement of control signal and lower the error rate during the QKD process.In order to verify the usefulness of the QKD broadband electronic control system,this dissertation implemented the QKD broadband electronic control system. With the help of the dual-way physical system, a QKD experimental system was built. This experimental system’s field test results prove: the QKD broadband electronic control system which is proposed can control the physical system correctly and can drive the physical system to transfer the information successfully. The QKD broadband electronic control system solved the physical system’s long-running operation control problem caused by different work frequencies, improved the usefulness of the QKD system.