Nonanomalous measure of realism-based nonlocality

TL;DR

This paper introduces a new measure of nonlocality based on realism, which differs from Bell nonlocality, aligns with entanglement for pure states, and can be present even in separable states, offering a fresh perspective on quantum nonlocality.

Contribution

It proposes a novel realism-based nonlocality measure, demonstrates its relation to entanglement, and explores its presence in separable states, expanding the understanding of quantum nonlocality.

Findings

Measure reduces to entanglement for pure states

States with null realism-based nonlocality identified

Nonlocality can occur in separable states

Abstract

Based on a recently proposed model of physical reality and an underlying criterion of nonlocality for contexts [A. L. O. Bilobran and R. M. Angelo, Europhys. Lett. {\bf 112}, 40005 (2015)], we introduce a quantifier of realism-based nonlocality for bipartite quantum states, a concept that is profoundly different from Bell nonlocality. We prove that this measure reduces to entanglement for pure states, thus being free of anomalies in arbitrary dimensions, and identify the class of states with null realism-based nonlocality. Then we show that such a notion of nonlocality can be positioned in a low level within the hierarchy of quantumness quantifiers, meaning that it can occur even for separable states. These results open a different perspective for nonlocality studies.