Discrete-phase-randomized coherent state source and its application in quantum key distribution. (13th May 2015)

• Record Type: Journal Article
• Authors: Cao, Zhu; Zhang, Zhen; Lo, Hoi-Kwong; Ma, Xiongfeng
• Is Part Of: New journal of physics. Volume 17:Number 5(2015:May)
• Publication Date: 2015-05-13
• Subjects: quantum key distribution -- coherent state -- discrete phase randomization -- decoy state; Physics -- Periodicals; Physics; Periodicals; 530.05
• DOI: 10.1088/1367-2630/17/5/053014
• Languages: English
• ISSNs: 1367-2630

Abstract

Abstract: Coherent state photon sources are widely used in quantum information processing. In many applications, such as quantum key distribution (QKD), a coherent state functions as a mixture of Fock states by assuming that its phase is continuously randomized. In practice, such a crucial assumption is often not satisfied, and therefore the security of existing QKD experiments is not guaranteed. To bridge this gap, we provide a rigorous security proof of QKD with discrete-phase-randomized coherent state sources. Our results show that the performance of the discrete-phase randomization case is close to its continuous counterpart with only a small number (say, 10) of discrete phases. Compared to the conventional continuous phase randomization case, where an infinite amount of random bits are required, our result shows that only a small amount (say, 4 bits) of randomness is needed.