Entanglement Generation Beyond Quantum Theory: From Product States to Popescu-Rohrlich Boxes

Abstract:Entanglement generation is a fundamental dynamical capability in quantum information science and underpins many quantum advantages. While quantum theory enables it through unitary dynamics, boxworld, a generalized probabilistic theory admitting Popescu--Rohrlich boxes with supraquantum correlations, has no reversible transformation capable of generating entanglement. We show that this no-go picture changes fundamentally once reversibility is relaxed to pure-state preservation. We construct a pure-state-preserving transformation that maps every uncorrelated pure state to a Popescu--Rohrlich box and completely classify all pure-state-preserving entangling transformations in the simplest bipartite boxworld. Our results provide the first explicit mechanism for generating beyond-quantum entanglement without introducing mixing and demonstrate a physical distinction between reversibility and pure-state preservation that is obscured by the structure of quantum theory.

arXiv:2608.02403 [quant-ph]

(or arXiv:2608.02403v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2608.02403 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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