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arXiv:2010.05503 · New Journal of Physics

Loophole-free plug-and-play quantum key distribution

Ruoyang Qi, Haoran Zhang, Jiancun Gao, Liuguo Yin, Gui‐Lu Long

Published May 24, 2021• 15 citations
arXivHTMLPDF

Abstract

Abstract Robust, simple, and flexible quantum key distribution (QKD) is vital for realizing practical applications of this technique. Contrary to typical phase-coded QKD schemes, the plug-and-play QKD design requires only one arm-length-insensitive interferometer without active feedback, in which the noise is automatically compensated by the two-way structure. However, there are certain possible loopholes in the typical plug-and-play designs, which require consideration and strict monitoring. This study proposes a new design of theoretically loophole-free plug-and-play QKD scheme with two-way protocol and presents an experimental demonstration of said scheme. The security is analyzed under a collective attack scenario assisted by the decoy state method. The scheme was implemented in a 50.4 km commercial fibre without active feedback. The system showed highly robust performance with an ultra-low error rate and maintained an ultra-high visibility of 0.9947 ± 0.0002 through significant environmental changes over 24 hours.

DOI
10.1088/1367-2630/ac0478

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Abstract Robust, simple, and flexible quantum key distribution (QKD) is vital for realizing practical applications of this technique. Contrary to typical phase-coded QKD schemes, the plug-and-play QKD design requires only one arm-length-insensitive interferometer without active feedback, in which the noise is automatically compensated by the two-way structure. However, there are certain possible loopholes in the typical plug-and-play designs, which require consideration and strict monitoring. This study proposes a new design of theoretically loophole-free plug-and-play QKD scheme with two-way protocol and presents an experimental demonstration of said scheme. The security is analyzed under a collective attack scenario assisted by the decoy state method. The scheme was implemented in a 50.4 km commercial fibre without active feedback. The system showed highly robust performance with an ultra-low error rate and maintained an ultra-high visibility of 0.9947 ± 0.0002 through significant environmental changes over 24 hours.
Robust, simple, and flexible quantum key distribution (QKD) is vital for realising practical applications of this technique. Contrary to typical phase-coded QKD schemes, the plug-and-play QKD design requires only one arm-length-insensitive interferometer without active feedback, in which the noise is automatically compensated by the two-way structure. However, there are certain possible loopholes in the typical plug-and-play designs, which require consideration and strict monitoring. This study proposes a new design of plug-and-play QKD based on two-way protocol with enhanced security and presents an experimental demonstration of said scheme. The security is analysed under a collective attack scenario assisted by the decoy state method. The scheme was implemented in a 50.4 km commercial fibre without active feedback. The system showed highly robust performance with an ultra-low error rate and maintained an ultra-high visibility of 0.9947+/-0.0002 through significant environmental changes over 24 hours. We analysis the performance of the system and give a brief discussion of the possible loopholes in practical applications.
Subject of study. Two-way continuous-variable quantum key distribution schemes are studied. Aim. This study aims to prove the security of the plug-and-play continuous-variable quantum key distribution system in the context of the model of trusted noise from legitimate users. Method. Based on an analog of the well-known implementation in the plug-and-play format, the performance of such a system operating under the GG02 protocol is evaluated. The evaluation is conducted in the presence of collective attacks, considering the finite-key effects. Main results. A secure key that satisfies the composability criteria can be distributed with a channel loss of 5 dB, which is expected to be approximately half that in a one-way scheme. Practical significance. Two-way quantum key distribution schemes are more stable than one-way schemes, and hence, their stability requires detailed consideration. This paper is the first, to our knowledge, to propose considering the security of a two-way implementation of continuous-variable quantum key distribution, considering the trusted equipment noise.
Abstract In this paper, a novel and highly efficient secure communication scheme is proposed through the integration of four-state modulation quantum key distribution and plug-and-play technology. This scheme serves the purpose of transmitting information reliably while preserving data confidentiality between two communicating parties. The most important advantage of the proposed continuous-variable QKD system is that the birefringence effect in fiber can be compensated automatically. Notably, simulation experimental evaluations are conducted, unveiling the performance of the plug-and-play four-state QKD which is as good as the four-state protocol when having small Rayleigh scattering noise. Furthermore, we conduct a comprehensive analysis of potential security threats targeted at the proposed protocol, thereby substantiating its robustness against such attacks. Moreover, theoretical justifications are provided to validate the security of the proposed scheme.
Abstract The round-robin differential-phase-shift quantum key distribution (RRDPS-QKD) protocol could provide an effective way to estimate the leakage information without monitoring the signal disturbance. Moreover, the self-compensating property of plug-and-play (P&P) setup can eliminate the variations of phase or polarization in QKD procedure. In the paper, we introduce the P&P concept into RRDPS-QKD, and propose a QKD protocol, named P&P RRDPS-QKD protocol, to make the RRDPS-QKD scheme more practical. We analyze the security, and discuss the key generation rate with infinite-intensity decoy state method. The results show that the proposed protocol is a good solution to RRDPS-QKD protocol with untrusted sources. It has a high security and its key generation rate could be as good as the protocol with trusted sources when the average input photon number N is greater than 106. In addition, the proposed protocol has a high noise tolerance in comparison with P&P BB84-QKD protocol.
The experiment of decoy state QKD has been reported using commercial QKD system based on a standard bi-directional `Plug & Play' set-up. By making simple modifications to a commercial quantum key distribution system, decoy state QKD allows us to achieve much better performance than QKD system without decoy state in terms of key generation rate and distance. One decoy state protocol has been implemented. The obtained results demonstrate an unconditionally secure key rate of 0.127 × 10-4 per pulse for a 10 km fiber length.