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arXiv · 2410.13499

Bell nonlocality from compatibility of entanglement-breaking channels

Gelo Noel M. Tabia·Chung-Yun Hsieh·Min-Hsiu Hsieh
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Abstract

Locally classical behavior is often interpreted as evidence that a global classical description should exist. In particular, when individual processes admit classical (measure-and-prepare) realizations, it is natural to expect at least one compatible joint implementation that remains classical. We show that this intuition fails in a simple broadcast setting with one input system and two outputs. Specifically, we construct pairs of compatible channels that are entanglement-breaking individually and thus admit classical descriptions, yet every joint broadcast realization is necessarily Bell-nonlocal between the outputs, even for a maximally mixed input. This establishes a form of compatibility-induced activation of nonlocality: Bell nonlocality arises not from entanglement in the inputs or marginal channels, but solely from the requirement that these marginals admit a common global implementation. In this sense, compatibility is not merely a consistency condition on local descriptions, but a mechanism that can enforce nonclassical correlations at the global level.

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Gelo Noel M. Tabia, Chung-Yun Hsieh, Min-Hsiu Hsieh. 2024-10-17. Bell nonlocality from compatibility of entanglement-breaking channels. https://arxiv.org/abs/2410.13499

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