Generalized Ardehali-Bell inequalities for graph states

TL;DR

This paper develops generalized Bell inequalities for graph states, extending Ardehali's method, and shows that nonstabilizer observables can outperform traditional GHZ-Mermin-type inequalities in quantum nonlocality tests.

Contribution

It introduces a new approach to derive Bell inequalities for graph states, broadening the scope beyond stabilizer-based inequalities.

Findings

Nonstabilizer observables often yield stronger violations.

Generalized inequalities outperform GHZ-Mermin-type inequalities.

Applicable to a wide class of graph states.

Abstract

We derive Bell inequalities for graph states by generalizing the approach proposed by Ardehali [Phys. Rev. A 46, 5375 (1992)] for Greenberger-Horne-Zeilinger (GHZ) states. Using this method, we demonstrate that Bell inequalities with nonstabilizer observables are often superior to the optimal GHZ-Mermin-type (or stabilizer-type) Bell inequalities.