Bilocal versus non-bilocal correlations in entanglement swapping experiments

TL;DR

This paper investigates bilocal correlations in entanglement swapping, deriving new Bell-type inequalities, analyzing their quantum violations, and showing that bilocality assumptions can reduce experimental demands for demonstrating quantum nonlocality.

Contribution

It extends previous analysis of bilocal correlations by deriving new inequalities, studying quantum violations, and assessing robustness in entanglement swapping scenarios.

Findings

New bilocal Bell inequalities derived for entanglement swapping

Quantum violations of these inequalities identified

Reduced experimental requirements for demonstrating nonlocality

Abstract

Entanglement swapping is a process by which two initially independent quantum systems can become entangled and generate nonlocal correlations. To characterize such correlations, we compare them to those predicted by bilocal models, where systems that are initially independent are described by uncorrelated states. We extend in this paper the analysis of bilocal correlations initiated in [Phys. Rev. Lett. 104, 170401 (2010)]. In particular, we derive new Bell-type inequalities based on the bilocality assumption in different scenarios, we study their possible quantum violations, and analyze their resistance to experimental imperfections. The bilocality assumption, being stronger than Bell's standard local causality assumption, lowers the requirements for the demonstration of quantumness in entanglement swapping experiments.