Nonlinear Bell inequalities tailored for quantum networks

TL;DR

This paper introduces a method to construct nonlinear Bell inequalities specifically designed for quantum networks, enabling the detection of quantum nonlocality in complex network configurations.

Contribution

The authors develop an iterative procedure to generate Bell inequalities for increasingly complex quantum networks, extending previous methods and demonstrating their effectiveness.

Findings

Significant quantum violations of the tailored Bell inequalities.

Method applicable to various network configurations.

Enhanced detection of nonlocal correlations in quantum networks.

Abstract

In a quantum network, distant observers sharing physical resources emitted by independent sources can establish strong correlations, which defy any classical explanation in terms of local variables. We discuss the characterization of nonlocal correlations in such a situation, when compared to those that can be generated in networks distributing independent local variables. We present an iterative procedure for constructing Bell inequalities tailored for networks: starting from a given network, and a corresponding Bell inequality, our technique provides new Bell inequalities for a more complex network, involving one additional source and one additional observer. The relevance of our method is illustrated on a variety of networks, for which we demonstrate significant quantum violations.