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arXiv:2405.06526

PBR, nonreality and entangled measurement

Hofer-Szabó, Gábor

Published May 10, 2024• 0 citations
arXivHTMLPDF

Abstract

In a recent paper, Cabbolet argues that the PBR theorem is nonreal since in the ensemble interpretation of quantum mechanics the entangled measurement used in the derivation of the PBR theorem is nonexisting. However, Cabbolet (1) doesn't provide any argument for the nonexistence of entangled measurements beyond the incompatibility of the existence of entangled measurements and the existence of $ψ$-epistemic models which we already know from the PBR theorem; and (2) he doesn't show why it is more reasonable to abandon entangled measurements instead of $ψ$-epistemic models. Hence, the PBR theorem remains intact.

DOI
10.48550/arxiv.2405.06526

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According to the current epistemic interpretation of quantum probabilities, the quantum correlations manifesting nonlocality can be derived from purely probabilistic and information-theoretic constraints. As such, they do not constitute a spacetime phenomenon and cannot lead to conflict between QM and any spatial-temporal constraints. This paper compares recent epistemic interpretations with earlier probabilistic interpretations, noting their merits as well as the difficulties they encounter. In particular, the implications of the recent PBR theorem are examined. While generally seen as undermining the epistemic interpretation, I argue that the PBR theorem actually suggests an epistemic position more radical than previously ones. This review of probabilistic interpretations enables reassessment of the epistemic theorist's attempt to disentangle nonlocality from spacetime considerations
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"In the past couple of months, the quantum foundations world has been abuzz about a new preprint entitled "The Quantum State Cannot be Interpreted Statistically" by Matt Pusey, Jon Barrett and Terry Rudolph (henceforth known as PBR). Since I wrote a blog post explaining the result, I have been inundated with more correspondence from scientists and more requests for comment from science journalists than at any other point in my career. Reaction to the result amongst quantum researchers has been mixed, with many people reacting negatively to the title, which can be misinterpreted as an attack on the Born rule. Others have managed to read past the title, but are still unsure whether to credit the result with any fundamental significance. In this article, I would like to explain why I think that the PBR result is the most significant constraint on hidden variable theories that has been proved to date. It provides a simple proof of many other known theorems, and it supercharges the EPR argument, converting it into a rigorous proof of nonlocality that has the same status as Bell's theorem. Before getting to this though, we need to understand the PBR result itself."