Kupczynski's Contextual Locally Causal Probabilistic Models are constrained by Bell's theorem

TL;DR

The paper demonstrates that Kupczynski's contextual local causal models are mathematically equivalent to Bell's local hidden variables models and cannot circumvent Bell's theorem, reaffirming the incompatibility of quantum mechanics with local realism.

Contribution

It proves that Kupczynski's models are a special case of Bell local models and cannot avoid Bell's inequality, clarifying misconceptions about contextuality and local realism.

Findings

Kupczynski's models are mathematically a subset of Bell local models.

Bell-CHSH inequality can be derived even with Kupczynski's contextual approach.

Recent loophole-free experiments violate Bell's inequality, invalidating Kupczynski's escape route.

Abstract

In a sequence of papers, Marian Kupczynski has argued that Bell's theorem can be circumvented if one takes correct account of contextual setting-dependent parameters describing measuring instruments. We show that this is not true. Despite first appearances, Kupczynksi's concept of a contextual locally causal probabilistic model is mathematically a special case of a Bell local hidden variables model. Thus, even if one takes account of contextuality in the way he suggests, the Bell-CHSH inequality can still be derived. Violation thereof by quantum mechanics cannot be easily explained away: quantum mechanics and local realism (including Kupczynski's claimed enlargement of the concept) are not compatible with one another. Further inspection shows that Kupczynski is actually falling back on the detection loophole. Since 2015, numerous loophole-free experiments have been performed, in which the Bell-CHSH inequality is violated, so despite any other possible imperfections of such experiments, Kupczynski's escape route for local realism is not available