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arXiv · 2611.04539

Decoy-state quantum key distribution with a leaky Mach-Zehnder receiver

Ryohei Mizusawa·Álvaro Navarrete·Akihiro Mizutani·Kiyoshi Tamaki
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Abstract

We prove the security of phase-encoded decoy-state BB84 quantum key distribution for a Mach-Zehnder receiver with imbalanced beam splitters and two threshold detectors that leak fine-grained information about the detection patterns. For this, we derive a lower bound on Bob's single-photon contributions and combine it with the decoy-state method and a recent phase-error framework for leaky receivers. The leakage-induced correction to the phase-error rate is independent of channel loss, providing a loss-tolerant treatment of receiver leakage even in the presence of beam-splitter imbalance. Our results provide a practical route toward loss-tolerant security proofs for imperfect QKD receivers in the presence of receiver leakage.

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Ryohei Mizusawa, Álvaro Navarrete, Akihiro Mizutani, Kiyoshi Tamaki. 2026-11-03. Decoy-state quantum key distribution with a leaky Mach-Zehnder receiver. https://arxiv.org/abs/2611.04539

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