Universal classical-quantum channel resolvability and private channel coding

Fuente: arXiv
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Autores principales: Matsuura, Takaya, Hayashi, Masahito, Hsieh, Min-Hsiu
Formato: Preprint
Publicado: 2025
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author Matsuura, Takaya
Hayashi, Masahito
Hsieh, Min-Hsiu
author_facet Matsuura, Takaya
Hayashi, Masahito
Hsieh, Min-Hsiu
contents We address the problem of constructing fully universal private channel coding protocols for classical-quantum (c-q) channels. Previous work constructed universal decoding strategies, but the encoder relied on random coding, which prevents fully universal code construction. In this work, we resolve this gap by identifying an explicit structural property of codebooks -- namely, the spectral expansion of an associated Schreier graph -- that guarantees universal channel resolvability. Our analysis reveals how this property can be related to channel resolvability through the theory of induced representation. Our main technical result shows that when the transition matrix of a graph associated with a codebook has a large spectral gap, the channel output induced by uniformly sampled codewords is asymptotically indistinguishable from the target output distribution, independently of the channel. This establishes the first deterministic, channel-independent construction of resolvability codebooks. Building on this, we construct a fully universal private channel coding protocol by combining it with universal c-q channel coding based on the Schur-Weyl duality. With appropriate modifications to the requirements on codebooks of universal c-q channel coding, we show that our fully universal private channel coding achieves the known optimal rate. This work thus sheds new light on the expander property of a graph in the context of secure communication.
format Preprint
id arxiv_https___arxiv_org_abs_2510_02883
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Universal classical-quantum channel resolvability and private channel coding
Matsuura, Takaya
Hayashi, Masahito
Hsieh, Min-Hsiu
Quantum Physics
Information Theory
Mathematical Physics
We address the problem of constructing fully universal private channel coding protocols for classical-quantum (c-q) channels. Previous work constructed universal decoding strategies, but the encoder relied on random coding, which prevents fully universal code construction. In this work, we resolve this gap by identifying an explicit structural property of codebooks -- namely, the spectral expansion of an associated Schreier graph -- that guarantees universal channel resolvability. Our analysis reveals how this property can be related to channel resolvability through the theory of induced representation. Our main technical result shows that when the transition matrix of a graph associated with a codebook has a large spectral gap, the channel output induced by uniformly sampled codewords is asymptotically indistinguishable from the target output distribution, independently of the channel. This establishes the first deterministic, channel-independent construction of resolvability codebooks. Building on this, we construct a fully universal private channel coding protocol by combining it with universal c-q channel coding based on the Schur-Weyl duality. With appropriate modifications to the requirements on codebooks of universal c-q channel coding, we show that our fully universal private channel coding achieves the known optimal rate. This work thus sheds new light on the expander property of a graph in the context of secure communication.
title Universal classical-quantum channel resolvability and private channel coding
topic Quantum Physics
Information Theory
Mathematical Physics
url https://arxiv.org/abs/2510.02883