Loss-tolerant quantum key distribution with detection efficiency mismatch

Alessandro Marcomini*, Akihiro Mizutani, Fadri Grünenfelder, Marcos Curty, Kiyoshi Tamaki

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Current implementations of quantum key distribution (QKD) typically rely on prepare-and-measure (P&M) schemes. Unfortunately, these implementations are not completely secure, unless security proofs fully incorporate all imperfections of real devices. So far, existing proofs have primarily focused on imperfections of either the light source or the measurement device. In this paper, we establish a security proof for the loss-tolerant P&M QKD protocol that incorporates imperfections in both the source and the detectors. Specifically, we demonstrate the security of this scheme when the emitted states deviate from the ideal ones and Bob’s measurement device does not meet the basis-independent detection efficiency condition. Furthermore, we conduct an experiment to characterise the detection efficiency mismatch of commercial single-photon detectors as a function of the polarisation state of the input light, and determine the expected secret key rate in the presence of state preparation flaws when using such detectors. Our work provides a way towards guaranteeing the security of actual implementations of widely deployed P&M QKD.

Original languageEnglish
Article number035002
JournalQuantum Science and Technology
Volume10
Issue number3
DOIs
StatePublished - 2025/10/01

Keywords

  • detection efficiency mismatch
  • loss-tolerant QKD
  • QKD
  • quantum communications
  • quantum cryptography

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Materials Science (miscellaneous)
  • Physics and Astronomy (miscellaneous)
  • Electrical and Electronic Engineering

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