Quantum nonlocality via local contextuality with qubit-qubit entanglement

TL;DR

This paper demonstrates that quantum nonlocality can be observed through local contextuality even with only qubit-qubit entanglement, expanding understanding of quantum correlations and potential experimental applications.

Contribution

It shows that nonlocality via local contextuality exists in qubit-qubit entangled systems, previously thought to require higher-dimensional systems.

Findings

Nonlocality via local contextuality is possible with qubit-qubit entanglement.

Clarifies the role of entanglement and contextuality in quantum nonlocality.

Supports potential experimental observation of nonlocality in simple systems.

Abstract

Quantum nonlocality can be revealed "via local contextuality" in qudit-qudit entangled systems with $d > 2$, that is, through the violation of inequalities containing Alice-Bob correlations that admit a local description, and Alice-Alice correlations (between the results of sequences of measurements on Alice's subsystem) that admit a local (but contextual) description. A fundamental question to understand the respective roles of entanglement and local contextuality is whether nonlocality via local contextuality exists when the parties have only qubit-qubit entanglement. Here we respond affirmatively to this question. This result further clarifies the connection between contextuality and nonlocality and opens the door for observing nonlocality via local contextuality in actual experiments.