Continuity of entropies via integral representations

Fuente: arXiv
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Auteurs principaux: Berta, Mario, Lami, Ludovico, Tomamichel, Marco
Format: Preprint
Publié: 2024
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author Berta, Mario
Lami, Ludovico
Tomamichel, Marco
author_facet Berta, Mario
Lami, Ludovico
Tomamichel, Marco
contents We show that Frenkel's integral representation of the quantum relative entropy provides a natural framework to derive continuity bounds for quantum information measures. Our main general result is a dimension-independent semi-continuity relation for the quantum relative entropy with respect to the first argument. Using it, we obtain a number of results: (1) a tight continuity relation for the conditional entropy in the case where the two states have equal marginals on the conditioning system, resolving a conjecture by Wilde in this special case; (2) a stronger version of the Fannes-Audenaert inequality on quantum entropy; (3) better estimates on the quantum capacity of approximately degradable channels; (4) an improved continuity relation for the entanglement cost; (5) general upper bounds on asymptotic transformation rates in infinite-dimensional entanglement theory; and (6) a proof of a conjecture due to Christandl, Ferrara, and Lancien on the continuity of 'filtered' relative entropy distances.
format Preprint
id arxiv_https___arxiv_org_abs_2408_15226
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Continuity of entropies via integral representations
Berta, Mario
Lami, Ludovico
Tomamichel, Marco
Quantum Physics
Information Theory
Mathematical Physics
We show that Frenkel's integral representation of the quantum relative entropy provides a natural framework to derive continuity bounds for quantum information measures. Our main general result is a dimension-independent semi-continuity relation for the quantum relative entropy with respect to the first argument. Using it, we obtain a number of results: (1) a tight continuity relation for the conditional entropy in the case where the two states have equal marginals on the conditioning system, resolving a conjecture by Wilde in this special case; (2) a stronger version of the Fannes-Audenaert inequality on quantum entropy; (3) better estimates on the quantum capacity of approximately degradable channels; (4) an improved continuity relation for the entanglement cost; (5) general upper bounds on asymptotic transformation rates in infinite-dimensional entanglement theory; and (6) a proof of a conjecture due to Christandl, Ferrara, and Lancien on the continuity of 'filtered' relative entropy distances.
title Continuity of entropies via integral representations
topic Quantum Physics
Information Theory
Mathematical Physics
url https://arxiv.org/abs/2408.15226