Analysis of Faraday–Michelson quantum key distribution system with unbalanced attenuation

• 作 者: 宋萧天 李宏伟 张春梅 王东 王双 银振强 陈巍 韩正甫
• 机 构: Key Laboratory of Quantum Information,CAS,University of Science and Technology of China,Synergetic I
• 出 处: Chinese Optics Letters
• 发表日期: 2015年01期
• 关键词: Michelson unbalanced Faraday modulator perfect realization insertion extremely e

Quantum key distribution(QKD) is a major research topic because it provides unconditional security. Unfortunately, many imperfections remain in QKD’s experimental realization. The Faraday–Michelson(FM) QKD system is proposed to eliminate these imperfections using polarization. However, the long arm’s phase modulator(PM) has an unexpected insertion loss, meaning that the state sent is no longer perfect. In this letter, we propose an alternative FM-QKD system structure, and analyze the security and key generation rate in comparison with the original system via different analysis methods. We find an obvious key rate improvement when the PM insertion loss is not extremely small.

Unfortunately, many imperfections remain in QKD’s experimental realization. The Faraday-Michelson (FM) QKD system is proposed to eliminate these imperfections using polarization. However, the long arm’s phase modulator (PM) has an unexpected insertion loss, meaning that the state sent is no longer perfect. In this letter, we propose an alternative FM-QKD system structure, and analyze the security and key generation rate in comparison with the original system via different analysis methods. We find an obvious key rate improvement when the PM insertion loss is not extremely small.