No Practical Quantum Broadcasting: Even Virtually

Fuente: arXiv
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Autori principali: Xiao, Yunlong, Liu, Xiangjing, Liu, Zhenhuan
Natura: Preprint
Pubblicazione: 2025
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author Xiao, Yunlong
Liu, Xiangjing
Liu, Zhenhuan
author_facet Xiao, Yunlong
Liu, Xiangjing
Liu, Zhenhuan
contents Quantum information cannot be broadcast -- an intrinsic limitation imposed by quantum mechanics. However, recent advances in virtual operations offer new insights into the no-broadcasting theorem. Here, we focus on the practical utility and introduce sample efficiency as a fundamental constraint, requiring any practical broadcasting protocol perform no worse than the naïve approach of direct preparation and distribution. We prove that no linear process -- whether quantum or beyond -- can simultaneously uphold sample efficiency, unitary covariance, permutation invariance, and classical consistency. This leads to a no-practical-broadcasting theorem, which places strict limits on the practical distribution of quantum information. By applying Schur-Weyl duality, we establish the uniqueness of the canonical 1-to-$N$ virtual broadcasting map that satisfies the latter three conditions, provide its construction, and determine its sample complexity through semidefinite programming. Finally, we explore the interplay between virtual broadcasting and a quantum spacetime framework, known as the pseudo-density operator, showing that their correspondence holds only in the 1-to-2 case, underscoring the fundamental asymmetry between spatial and temporal statistics in the quantum world.
format Preprint
id arxiv_https___arxiv_org_abs_2503_16380
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle No Practical Quantum Broadcasting: Even Virtually
Xiao, Yunlong
Liu, Xiangjing
Liu, Zhenhuan
Quantum Physics
Quantum information cannot be broadcast -- an intrinsic limitation imposed by quantum mechanics. However, recent advances in virtual operations offer new insights into the no-broadcasting theorem. Here, we focus on the practical utility and introduce sample efficiency as a fundamental constraint, requiring any practical broadcasting protocol perform no worse than the naïve approach of direct preparation and distribution. We prove that no linear process -- whether quantum or beyond -- can simultaneously uphold sample efficiency, unitary covariance, permutation invariance, and classical consistency. This leads to a no-practical-broadcasting theorem, which places strict limits on the practical distribution of quantum information. By applying Schur-Weyl duality, we establish the uniqueness of the canonical 1-to-$N$ virtual broadcasting map that satisfies the latter three conditions, provide its construction, and determine its sample complexity through semidefinite programming. Finally, we explore the interplay between virtual broadcasting and a quantum spacetime framework, known as the pseudo-density operator, showing that their correspondence holds only in the 1-to-2 case, underscoring the fundamental asymmetry between spatial and temporal statistics in the quantum world.
title No Practical Quantum Broadcasting: Even Virtually
topic Quantum Physics
url https://arxiv.org/abs/2503.16380