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arXiv · 2201.03039

Finite-key analysis for quantum key distribution with discrete phase randomization

Rui Qiang Wang·Zhen Qiang yin·Rong Wang·Shuang Wang·Wei Chen·Guang can Guo·Zhen fu Han
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Abstract

Quantum key distribution(QKD) allows two remote parties to share information-theoretic secret keys. Many QKD protocols assume the phase of encoding state can be continuous randomized from 0 to 2 pi, which, however, may be questionable in experiment. This is particularly the case in the recently proposed twin-field(TF) QKD, which has received a lot of attention, since it can increase key rate significantly and even beat some theoretical rate-loss limits. As an intuitive solution, one may introduce discrete phase-randomization instead of continuous one. However, a security proof for a QKD protocol with discrete phase-randomization in finite-key region is still missing. Here we develop a technique based on conjugate measurement and quantum state distinguishment to ana-lyze the security in this case. Our result shows that TF-QKD with reasonable number of discrete random phases, e.g. 8 phases from {0, pi/4, pi/2, ..., 7pi/4}, can achieve satisfactory performance. More importantly, as a the first proof for TF-QKD with discrete phase-randomization in finite-key region, our method is also applicable in other QKD protocols.

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Rui Qiang Wang, Zhen Qiang yin, Rong Wang, Shuang Wang, Wei Chen, Guang can Guo, Zhen fu Han. 2022-01-09. Finite-key analysis for quantum key distribution with discrete phase randomization. https://doi.org/10.3390/e25020258

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