Multiple-pulse phase-matching quantum key distribution
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Multiple-pulse phase-matching quantum key distribution Gang Chen1 · Le Wang1 · Wei Li1 · Yang Zhao1,2 · Shengmei Zhao1,2 Jozef Gruska3
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Received: 17 June 2020 / Accepted: 29 October 2020 / Published online: 13 November 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract We propose a multiple-pulse phase-matching quantum key distribution protocol to exceed the linear key rate bound and to achieve higher error tolerance. In our protocol, Alice and Bob generate at first their own pulse train (each train should contain L pulses) as well as random bit sequences and also encode each pulse of their train with a randomized phase and a modulation phase. As the next step, both encoded trains are simultaneously sent to Charlie, who performs an interference detection and may be also an eavesdropper. After a successful detection is announced by Charlie, Alice and Bob open the randomized phase of each pulse and keep only communications when the summation of the difference randomized phases at two success detections’ time stamps for Alice and Bob is equal to 0 or π . Thereafter, Alice and Bob compute the sifted key with the time stamps. The above procedure is repeated until both Alice and Bob achieve sufficiently long sifted keys. We can also show that the secret key rate of the proposed QKD protocol can beat the rate-loss limit of so far known QKD protocols when the transmission distance is greater than 150–175 km. Moreover, the proposed protocol has a higher error tolerance, approximately 22.5%, when the transmission distance is 50 km and L = 128. The secret key rate and the transmission distance of our protocol are superior to that of the round-robin differential phase shift quantum key distribution protocol Sasaki et al. (Nature 509:475–480, 2014) and the measurement-device-independent quantum key distribution protocol Lo et al. (Phys Rev Lett 108:130503, 2012), and the secret key rate performance is better in both cases than that of phase-matching quantum key distribution when bit train length is greater than 16.
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Shengmei Zhao [email protected]
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Institute of Signal Processing Transmission, Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210003, China
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Key Lab of Broadband Wireless Communication and Sensor Network Technology, Ministry of Education, Nanjing 210003, China
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Faculty of informatics, Masaryk University, Botanická 68a, 60200 Brno, Czech Republic
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Keywords Quantum key distribution · Phase modulation · Round-robin differential phase shift · Secret key rate
1 Introduction Quantum key distribution (QKD) protocols allow two distant parties (Alice and Bob) to produce and share a secret classical key even at the existence of an eavesdropper (Eve) [1,2]. In both theory and experiments, QKD protocols are expected to be more and more extensively applied in various practical situations [3–16]. However, transmission losses of photons have become one of the major obstacles in practical implementations of QKD protocol [1
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