Higher key rate of measurement-device-independent quantum key distribution through joint data processing

Cong Jiang, Zong-Wen Yu, Xiao-Long Hu, and Xiang-Bin Wang

Phys. Rev. A 103, 012402 – Published 8 January 2021

Abstract

We propose a method named as double-scanning method to improve the key rate of measurement-device-independent quantum key distribution (MDI-QKD) drastically. In the method, two parameters are scanned simultaneously to tightly estimate the counts of single-photon pairs and the phase-flip error rate jointly. Numerical results show that the method in this work can improve the key rate by $35 % - 280 %$ in a typical experimental setup. Besides, we study the optimization of MDI-QKD protocol with all parameters including the source parameters and failure probability parameters, over symmetric channel or asymmetric channel. Compared with the optimized results with only the source parameters, the all-parameter-optimization method could improve the key rate by about $10 %$ .

Received 17 July 2020
Accepted 16 December 2020

DOI:https://doi.org/10.1103/PhysRevA.103.012402

Physics Subject Headings (PhySH)

Quantum communication Quantum cryptography

Quantum Information, Science & Technology

Authors & Affiliations

Cong Jiang¹, Zong-Wen Yu^2,3, Xiao-Long Hu², and Xiang-Bin Wang ^1,2,4,5,*

¹Jinan Institute of Quantum Technology, SAICT, Jinan 250101, China
²State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
³Data Communication Science and Technology Research Institute, Beijing 100191, China
⁴Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
⁵Shenzhen Institute for Quantum Science and Engineering, and Physics Department, Southern University of Science and Technology, Shenzhen 518055, China

^*Also at Center for Atomic and Molecular Nanosciences, Tsinghua University, Beijing 100084, China; xbwang@mail.tsinghua.edu.cn

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Vol. 103, Iss. 1 — January 2021

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Images

Figure 1
The schematic set-up of 4-intensity MDI-QKD protocol [46]. Alice (Bob) takes encoding in $X$ basis for sources $o_{A}, x_{A}, y_{A}$ ( $o_{B}, x_{B}, y_{B}$ ) and encoding in $Z$ basis for source $z_{A} (z_{B})$ . In practice, there is no complete Bell measurement device for Charlie. Even in such a case, Alice and Bob can still use those effective events for the decoy-state analysis and final key distillation [39, 46].
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Figure 2
Key rates of the 4-intensity protocol through different calculation methods in the symmetric channel. The experimental parameters used here are listed in Table 1. The “‘Improved-all-parameter” line shows the results of the double-scanning method of this work optimized with all the parameters including the source parameters and failure probability parameters. The “Improved-6-parameter” line shows the results of the double-scanning method of this work with only the source parameters optimized. The “Original-all-parameter” line shows the results of the single-scanning method of Ref. [46] optimized with all the parameters including the source parameters and failure probability parameters. The “Original-6-parameter” line shows the results of the single-scanning method of Ref. [46] with only the source parameters optimized.
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Figure 3
Key rates of the 4-intensity protocol through different calculation methods in the asymmetric channel. The distance difference between Alice to Charlie and Bob to Charlie is set as 20 km. The other experimental parameters used here are listed in Table 1. The “Improved-all-parameter” line shows the results of the double-scanning method of this work optimized with all the parameters including the source parameters and failure probability parameters. The “Improved-12-parameter” line shows the results of the double-scanning method of this work with only the source parameters optimized. The “Original-all-parameter” line shows the results of the single-scanning method of Ref. [46] optimized with all the parameters including the source parameters and failure probability parameters. The “Original-12-parameter” line shows the results of the single-scanning method of Ref. [46] with only the source parameters optimized.
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Figure 4
Key rates of the 4-intensity protocol and 3-intensity protocol through different calculation methods in the symmetric channel. The experimental parameters used here are listed in Table 1. The `Improved method' lines are the results of the double-scanning method, and the ``Original method'' lines are the results of the single scanning method [46]. The $μ_{a z} \neq μ_{a y}$ lines are the results of the 4-intensity protocol and the $μ_{a z} = μ_{a y}$ lines are the results of the 3-intensity protocol.
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