FPGA based digital phase-coding quantum key distribution system

• Published in: Science China. Physics, mechanics & astronomy mechanics & astronomy, 2015-12, Vol.58 (12), p.153-159, Article 120301
• Main Authors: Lu, XiaoMing, Zhang, LiJun, Wang, YongGang, Chen, Wei, Huang, DaJun, Li, Deng, Wang, Shuang, He, DeYong, Yin, ZhenQiang, Zhou, Yu, Hui, Cong, Han, ZhengFu
• Format: Article
• Language: English
• Subjects: Astronomy; Bit error rate; Classical and Continuum Physics; Coding; Computer networks; Continuous fiber composites; Continuous fibers; Electronics; Field programmable gate arrays; FPGA; Information theory; Interferometers; Manuals; Michelson interferometers; Modulation; Observations and Techniques; Physics; Physics and Astronomy; Quantum cryptography; Qubits (quantum computing); Security; 分发系统; 实验室环境; 现场可编程门阵列; 相位编码; 调制速率; 迈克尔逊干涉仪; 量子密钥分配
• ISSN: 1674-7348; 1869-1927
• DOI: 10.1007/s11433-015-5742-z

Quantum key distribution （QKD） is a technology with the potential capability to achieve information-theoretic security. Phase- coding is an important approach to develop practical QKD systems in fiber channel. In order to improve the phase-coding modulation rate, we proposed a new digital-modulation method in this paper and constructed a compact and robust prototype of QKD system using currently available components in our lab to demonstrate the effectiveness of the method. The system was deployed in laboratory environment over a 50 km fiber and continuously operated during 87 h without manual interaction. The quantum bit error rate （QBER） of the system was stable with an average value of 3.22% and the secure key generation rate is 8.91 kbps. Although the modulation rate of the photon in the derno system was only 200 MHz, which was limited by the Faraday- Michelson interferometer （FMI） structure, the proposed method and the field programmable gate array （FPGA） based electronics scheme have a great potential for high speed QKD systems with Giga-bits/second modulation rate.