Genuinely entangled subspaces beyond strongly nonlocal unextendible biseparable bases

Fuente: arXiv
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Auteurs principaux: Bera, Subrata, Bhunia, Atanu, Biswas, Indranil, Chattopadhyay, Indrani, Sarkar, Debasis
Format: Preprint
Publié: 2025
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author Bera, Subrata
Bhunia, Atanu
Biswas, Indranil
Chattopadhyay, Indrani
Sarkar, Debasis
author_facet Bera, Subrata
Bhunia, Atanu
Biswas, Indranil
Chattopadhyay, Indrani
Sarkar, Debasis
contents Quantum information theory reveals a clear distinction between local and nonlocal correlations through the entanglement across spatially separated subsystems. The orthogonal complement of an unextendible biseparable basis (UBB) consists entirely of genuine multipartite entangled states, representing the most robust form of such nonlocal correlations. In this letter, we provide a sufficient condition for any subspace to be genuinely entangled, enabling the systematic construction of high-dimensional genuinely entangled subspaces (GESs) from UBBs. Our construction yields the largest known GES ever obtained from a UBB. In fact, every state in this subspace is 1-distillable across every bipartition which is one of the crucial result we obtained. Furthermore, we prove that every UBB is indistinguishable under LOCC protocols, underscoring a distinct manifestation of quantum nonlocality. The UBBs we construct exhibit strong nonlocality in this scenario, making cryptographic protocols secure not only against LOCC-based attacks but also against coordinated group attacks. We introduce a no-go condition that certifies such an extreme form of nonlocality. All previously known UBBs satisfy this condition, which may lead to the misconception that strong nonlocality is an inherent property of every UBB. However, we construct a UBB that violates the no-go condition and exhibits locality across certain bipartitions, challenging conventional notions of unextendibility and nonlocality in multipartite quantum systems.
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publishDate 2025
record_format arxiv
spellingShingle Genuinely entangled subspaces beyond strongly nonlocal unextendible biseparable bases
Bera, Subrata
Bhunia, Atanu
Biswas, Indranil
Chattopadhyay, Indrani
Sarkar, Debasis
Quantum Physics
Quantum information theory reveals a clear distinction between local and nonlocal correlations through the entanglement across spatially separated subsystems. The orthogonal complement of an unextendible biseparable basis (UBB) consists entirely of genuine multipartite entangled states, representing the most robust form of such nonlocal correlations. In this letter, we provide a sufficient condition for any subspace to be genuinely entangled, enabling the systematic construction of high-dimensional genuinely entangled subspaces (GESs) from UBBs. Our construction yields the largest known GES ever obtained from a UBB. In fact, every state in this subspace is 1-distillable across every bipartition which is one of the crucial result we obtained. Furthermore, we prove that every UBB is indistinguishable under LOCC protocols, underscoring a distinct manifestation of quantum nonlocality. The UBBs we construct exhibit strong nonlocality in this scenario, making cryptographic protocols secure not only against LOCC-based attacks but also against coordinated group attacks. We introduce a no-go condition that certifies such an extreme form of nonlocality. All previously known UBBs satisfy this condition, which may lead to the misconception that strong nonlocality is an inherent property of every UBB. However, we construct a UBB that violates the no-go condition and exhibits locality across certain bipartitions, challenging conventional notions of unextendibility and nonlocality in multipartite quantum systems.
title Genuinely entangled subspaces beyond strongly nonlocal unextendible biseparable bases
topic Quantum Physics
url https://arxiv.org/abs/2508.17154