Security proof of practical quantum key distribution with detection-efficiency mismatch

Quantum key distribution (QKD) protocols with threshold detectors are driving high-performance QKD demonstrations. The corresponding security proofs usually assume that all physical have the same detection efficiency. However, efficiencies of used in practice might show a mismatch depending on manufacturing and setup these detectors. A can also be induced as different spatial-temporal modes an incoming signal couple differently to detector. Here we develop method allows provide without usual assumption. Our take detection-efficiency into account having restrict attack strategy adversary. Especially, do not rely any photon-number cutoff signals such our proof is directly applicable practical situations. We illustrate for receiver designed polarization encoding sensitive number modes. In detector model, absence quantum interference between pair assumed. For protocol this perform characterized efficiency shows rate increases if loss due inefficiency assumed outside adversary's control, compared view where attributed action adversary.3 MoreReceived 16 April 2020Accepted 7 January 2021DOI:https://doi.org/10.1103/PhysRevResearch.3.013076Published by American Physical Society under terms Creative Commons Attribution 4.0 International license. Further work must maintain attribution author(s) published article's title, journal citation, DOI.Published SocietyPhysics Subject Headings (PhySH)Research AreasQuantum cryptographyQuantum Information