Security Analysis of Quantum Key Distribution with Small Block Length and Its Application to Quantum Space Communications

Charles Ci-Wen Lim, Feihu Xu, Jian-Wei Pan, and Artur Ekert
Phys. Rev. Lett. 126, 100501 – Published 9 March 2021

Abstract

The security of real-world quantum key distribution (QKD) critically depends on the number of data points the system can collect in a finite time interval. To date, state-of-the-art finite-key security analyses require block lengths in the order of 104bits to obtain positive secret keys. This requirement, however, can be very difficult to achieve in practice, especially in the case of entanglement-based satellite QKD, where the overall channel loss can go up to 70 dB or more. Here, we provide an improved finite-key security analysis which reduces the block length requirement by 14% to 17% for standard channel and protocol settings. In practical terms, this reduction could save entanglement-based satellite QKD weeks of measurement time and resources, thereby bringing space-based QKD technology closer to reality. As an application, we use the improved analysis to show that the recently reported Micius QKD satellite is capable of generating positive secret keys with a 105 security level.

  • Figure
  • Received 28 September 2020
  • Accepted 5 February 2021

DOI:https://doi.org/10.1103/PhysRevLett.126.100501

© 2021 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & Technology

Authors & Affiliations

Charles Ci-Wen Lim1,2,*, Feihu Xu3,4, Jian-Wei Pan3,4, and Artur Ekert2,5

  • 1Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583
  • 2Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543
  • 3Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
  • 4Shanghai Branch, CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
  • 5Mathematical Institute, University of Oxford, Woodstock Rd, Oxford OX2 6HD, United Kingdom

  • *charles.lim@nus.edu.sg

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Vol. 126, Iss. 10 — 12 March 2021

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