Leggett-type $N$-partite scenarios for testing nonlocal realistic theory

TL;DR

This paper extends Leggett-type nonlocal realistic models to multipartite systems, deriving stronger inequalities that quantum mechanics can violate, thus providing new ways to experimentally test nonlocal realism in complex quantum states.

Contribution

It generalizes Leggett-type inequalities to N-partite systems and demonstrates their violation by quantum states like GHZ, offering a new framework for testing nonlocal realism.

Findings

Quantum violations of Leggett-type inequalities in GHZ states.

Stronger inequalities for N-partite systems.

Experimental testability of nonlocal realism in multipartite scenarios.

Abstract

The nonlocal realistic theory might be the last cornerstone of classical physics confronting to the quantum theory, which was found mostly untenable in the bipartite system [Nature 446, 871 (2007)]. We extend the Leggett-type nonlocal realistic model to arbitrary $N$-partite systems with polarizer settings, and obtain some stronger inequalities to distinguish quantum mechanics from nonlocal realistic theories. For illustration, with certain measurement settings the quantum violations of Leggett-type inequalities are found for Greenberger-Horne-Zeilinger (GHZ) state. Our results, say the nonlocal realism in multipartite systems, are testable in experiment.