English

Bell inequalities for nonlocality depth

Quantum Physics 2023-02-13 v2

Abstract

When three or more particles are considered, quantum correlations can be stronger than the correlations generated by so-called hybrid local hidden variable models, where some of the particles are considered as a single block inside which communication and signaling is allowed. We provide an exhaustive classification of Bell inequalities to characterize various hybrid scenarios in four- and five-particle systems. In quantum mechanics, these inequalities provide device-independent witnesses for the entanglement depth. In addition, we construct a family of inequalities to detect a non-locality depth of (n-1) in n-particle systems. Moreover, we present two generalizations of the original Svetlichny inequality, which was the first Bell inequality designed for hybrid models. Our results are based on the cone-projection technique, which can be used to completely characterize Bell inequalities under affine constraints; even for many parties, measurements, and outcomes.

Keywords

Cite

@article{arxiv.2205.04250,
  title  = {Bell inequalities for nonlocality depth},
  author = {Fabian Bernards and Otfried Gühne},
  journal= {arXiv preprint arXiv:2205.04250},
  year   = {2023}
}

Comments

12 pages, 3 figures, v2: final version

R2 v1 2026-06-24T11:11:27.236Z