Making the most of leftovers: Improved privacy amplification for quantum key distribution
Abstract
The amount of secret key that can be obtained from a quantum key distribution run depends on both the physically observed error rates and the mathematical bounds used to certify security. For finite datasets, conservative bounds force users to discard a substantial fraction of the potentially available key. Here we further refine and extend the privacy amplification bounds achievable through the recent leftover hash lemma of Regula and Tomamichel [arXiv:2603.04493] and incorporate them into the security analysis of quantum key distribution based on entropic uncertainty relations. This improves on state-of-the-art key rates in finite-block regimes, certifying more secret key from the same experimental data without changes to the protocol, and outperforming techniques based on entropy accumulation. The results illustrate how sharper mathematical estimates can directly increase the usable output of a quantum communication system.
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BibTeX
@misc{tan2026making,
title = {{Making the most of leftovers: Improved privacy amplification for quantum key distribution}},
author = {Matthew Simon Tan and Bartosz Regula and Marco Tomamichel},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.38306},
eprint = {2609.38306},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.38306},
}
RIS
TY - UNPB
TI - Making the most of leftovers: Improved privacy amplification for quantum key distribution
AU - Matthew Simon Tan
AU - Bartosz Regula
AU - Marco Tomamichel
PY - 2026
DA - 2026/09/29
PB - arXiv
DO - 10.48550/arxiv.2609.38306
UR - https://arxiv.org/abs/2609.38306
AB - The amount of secret key that can be obtained from a quantum key distribution run depends on both the physically observed error rates and the mathematical bounds used to certify security. For finite datasets, conservative bounds force users to discard a substantial fraction of the potentially available key. Here we further refine and extend the privacy amplification bounds achievable through the recent leftover hash lemma of Regula and Tomamichel [arXiv:2603.04493] and incorporate them into the security analysis of quantum key distribution based on entropic uncertainty relations. This improves on state-of-the-art key rates in finite-block regimes, certifying more secret key from the same experimental data without changes to the protocol, and outperforming techniques based on entropy accumulation. The results illustrate how sharper mathematical estimates can directly increase the usable output of a quantum communication system.
ER -