Essential Duality and Maximal Non-signalling Extensions in Algebraic Quantum Field Theory

Fuente: arXiv
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Main Author: Nasreddine, Hassan
Format: Preprint
Published: 2026
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author Nasreddine, Hassan
author_facet Nasreddine, Hassan
contents We show that, under additivity, the maximal von Neumann algebra extension of $\mathcal{A}(O)$ inside $B(\mathcal{H})$ whose inner automorphisms are non-signalling with respect to all spacelike-separated regions is $\mathcal{A}(O')'$. Consequently, $\mathcal{A}(O)$ is maximal with respect to this property if and only if essential duality holds. The proof is purely algebraic. When essential duality fails, we construct a proper extension all of whose inner automorphisms, and more generally all normal completely positive maps admitting Kraus operators in the algebra, are non-signalling. Under essential duality, any proper extension necessarily admits a signalling operation. An entropic formulation using Araki relative entropy provides a quantitative diagnostic of signalling, though it is not used in the proof. Additional structural results include the wedge-intersection identity $\mathcal{A}(O')' = \bigcap_{W \supset O}\mathcal{A}(W)$ and equivalent characterisations of essential duality. These results identify essential duality as an operational maximality condition within the given representation.
format Preprint
id arxiv_https___arxiv_org_abs_2605_00075
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Essential Duality and Maximal Non-signalling Extensions in Algebraic Quantum Field Theory
Nasreddine, Hassan
Quantum Physics
Mathematical Physics
46L60 (Primary), 81T05, 46L30 (Secondary)
We show that, under additivity, the maximal von Neumann algebra extension of $\mathcal{A}(O)$ inside $B(\mathcal{H})$ whose inner automorphisms are non-signalling with respect to all spacelike-separated regions is $\mathcal{A}(O')'$. Consequently, $\mathcal{A}(O)$ is maximal with respect to this property if and only if essential duality holds. The proof is purely algebraic. When essential duality fails, we construct a proper extension all of whose inner automorphisms, and more generally all normal completely positive maps admitting Kraus operators in the algebra, are non-signalling. Under essential duality, any proper extension necessarily admits a signalling operation. An entropic formulation using Araki relative entropy provides a quantitative diagnostic of signalling, though it is not used in the proof. Additional structural results include the wedge-intersection identity $\mathcal{A}(O')' = \bigcap_{W \supset O}\mathcal{A}(W)$ and equivalent characterisations of essential duality. These results identify essential duality as an operational maximality condition within the given representation.
title Essential Duality and Maximal Non-signalling Extensions in Algebraic Quantum Field Theory
topic Quantum Physics
Mathematical Physics
46L60 (Primary), 81T05, 46L30 (Secondary)
url https://arxiv.org/abs/2605.00075