PreprintarXiv licencearXiv
Energy-constrained two-way capacities of the pure-loss channel
Abstract
We determine the two-way quantum and secret-key capacities of the pure-loss channel under an average input photon-number constraint. For transmissivity η and photon budget N, both capacities equal $g(N)-g((1-η)N)$, where g is the entropy of a thermal state. This coincides with the rate achieved by the known reverse coherent information of a two-mode squeezed vacuum. Our result provides the last missing capacity formula for the celebrated pure-loss channel, completing the picture of bosonic quantum communication under pure loss.
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BibTeX
@misc{falco2026energyconstrained,
title = {{Energy-constrained two-way capacities of the pure-loss channel}},
author = {Alessandro Falco and Francesco Anna Mele and Ludovico Lami and Vittorio Giovannetti},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.12365},
eprint = {2610.12365},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.12365},
}
RIS
TY - UNPB
TI - Energy-constrained two-way capacities of the pure-loss channel
AU - Alessandro Falco
AU - Francesco Anna Mele
AU - Ludovico Lami
AU - Vittorio Giovannetti
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2610.12365
UR - https://arxiv.org/abs/2610.12365
AB - We determine the two-way quantum and secret-key capacities of the pure-loss channel under an average input photon-number constraint. For transmissivity η and photon budget N, both capacities equal $g(N)-g((1-η)N)$, where g is the entropy of a thermal state. This coincides with the rate achieved by the known reverse coherent information of a two-mode squeezed vacuum. Our result provides the last missing capacity formula for the celebrated pure-loss channel, completing the picture of bosonic quantum communication under pure loss.
ER -