Security proofs for practical QKD: Variations, techniques, gaps, and limitations
Rev. Mod. Phys. 98, 035003 – Published 8 September, 2026
DOI: https://doi.org/10.1103/28rs-frmw
Abstract
The current status of security proofs for practical decoy-state quantum key distribution is reviewed using the Bennett-Brassard 1984 protocol, with a focus on optical implementations with weak coherent pulses and threshold photodetectors. The primary aim of this review is to highlight gaps in the existing literature. Such gaps may arise, for instance, from mismatches between detailed protocol specifications and proof-technique elements, reliance on earlier results based on different assumptions, or protocol choices that overlook real-world requirements. While substantial progress has been made, this overview draws attention to the details that still demand careful attention.
