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arXiv · 2409.05491

A refined Frauchiger--Renner paradox based on strong contextuality

Laurens Walleghem·Rui Soares Barbosa·Matthew F. Pusey·Stefan Weigert
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Abstract

The Frauchiger--Renner paradox derives an inconsistency when quantum theory is used to describe the use of itself, by means of a scenario where agents model other agents quantumly and reason about each other's knowledge. We observe that logical contextuality (\`a la Hardy) is the key ingredient of the FR paradox, and we provide a stronger paradox based on the strongly contextual GHZ--Mermin scenario. In contrast to the FR paradox, this GHZ--FR paradox neither requires post-selection nor any reasoning by observers who are modelled quantumly. If one accepts the universality of quantum theory including superobservers, we propose a natural extension of Peres's dictum to resolve these extended Wigner's friend paradoxes.

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Laurens Walleghem, Rui Soares Barbosa, Matthew F. Pusey, Stefan Weigert. 2024-09-09. A refined Frauchiger--Renner paradox based on strong contextuality. https://doi.org/10.22331/q-2026-05-26-2116

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