Phase error rate estimation in QKD with imperfect detectors

Fuente: arXiv
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Main Authors: Tupkary, Devashish, Nahar, Shlok, Sinha, Pulkit, Lütkenhaus, Norbert
Format: Preprint
Published: 2024
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author Tupkary, Devashish
Nahar, Shlok
Sinha, Pulkit
Lütkenhaus, Norbert
author_facet Tupkary, Devashish
Nahar, Shlok
Sinha, Pulkit
Lütkenhaus, Norbert
contents We present a finite-size security proof of the decoy-state BB84 QKD protocol against coherent attacks, using entropic uncertainty relations, for imperfect detectors. We apply this result to the case of detectors with imperfectly characterized basis-efficiency mismatch. Our proof works by obtaining a suitable bound on the phase error rate, without requiring any new modifications to the protocol steps or hardware. It is applicable to imperfectly characterized detectors, and only requires the maximum relative difference in detection efficiencies and dark count rates of the detectors to be characterized. Moreover, our proof allows Eve to choose detector efficiencies and dark count rates in their allowed ranges in each round, thereby addressing an important problem of detector side channels. We prove security in the variable-length framework, where users are allowed to adaptively determine the length of key to be produced, and number of bits to be used for error-correction, based on observations made during the protocol. We quantitatively demonstrate the effect of basis-efficiency mismatch by applying our results to the decoy-state BB84 protocol.
format Preprint
id arxiv_https___arxiv_org_abs_2408_17349
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Phase error rate estimation in QKD with imperfect detectors
Tupkary, Devashish
Nahar, Shlok
Sinha, Pulkit
Lütkenhaus, Norbert
Quantum Physics
We present a finite-size security proof of the decoy-state BB84 QKD protocol against coherent attacks, using entropic uncertainty relations, for imperfect detectors. We apply this result to the case of detectors with imperfectly characterized basis-efficiency mismatch. Our proof works by obtaining a suitable bound on the phase error rate, without requiring any new modifications to the protocol steps or hardware. It is applicable to imperfectly characterized detectors, and only requires the maximum relative difference in detection efficiencies and dark count rates of the detectors to be characterized. Moreover, our proof allows Eve to choose detector efficiencies and dark count rates in their allowed ranges in each round, thereby addressing an important problem of detector side channels. We prove security in the variable-length framework, where users are allowed to adaptively determine the length of key to be produced, and number of bits to be used for error-correction, based on observations made during the protocol. We quantitatively demonstrate the effect of basis-efficiency mismatch by applying our results to the decoy-state BB84 protocol.
title Phase error rate estimation in QKD with imperfect detectors
topic Quantum Physics
url https://arxiv.org/abs/2408.17349