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  • Open Access

Performance of the BB84 protocol without decoy states under varying announcement structures

Zhiyao Wang*,†, Aodhán Corrigan*,‡, and Norbert Lütkenhaus§

  • *These authors contributed equally to this work.
  • †Contact author: z2425wan@uwaterloo.ca
  • ‡Contact author: aodhan.corrigan@uwaterloo.ca
  • §Contact author: lutkenhaus.office@uwaterloo.ca
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Phys. Rev. A 114, 032429 – Published 14 September, 2026

DOI: https://doi.org/10.1103/ybl1-j3td

Abstract

In phase-randomized weak coherent pulse (WCP) implementations of the quantum key distribution (QKD) BB84 protocol, the decoy method is often used to compensate BB84's vulnerability against photon number splitting attacks. However, this typically introduces extra complexities and requirements on experimental devices. In this paper, we are therefore interested in phase-randomized WCP implementations without the decoy method. We examine the performance of three QKD protocols with different classical announcement structures, namely, BB84, SARG04, and No Public Announcement of Basis (NPAB) BB84, using numerical security proof techniques. Key rates are computed using the openqkd security software [J. Burniston et al., software openqkdsecurity, ver. 2.0.2 (2024)]. We compare secure key rates of the three protocols in asymptotic and finite-size regimes for lossy and noisy channels. The three protocols show different relative advantages depending on the channel behavior. Canonical BB84 shows robustness against errors and depolarization, SARG04 demonstrates resilience against high-loss channels, and NPAB BB84 shows potential advantages against physical misalignment between QKD devices.

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Phys. Rev. A 114, 032429– Published 14 September, 2026
  • Received 6 April 2026
  • Accepted 12 August 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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