Bell inequalities with a magnitude of violation that grows exponentially with the number of particles.

Abstract

A simple Bell inequality for an n-particle system in a Greenberger-Horne-Zeilinger state is derived. Quantum mechanics violates this inequality by an exponentially large factor of ${2}^{(\mathit{n}\mathrm{\ensuremath{-}}2)/2}$ for n odd or ${2}^{(\mathit{n}\mathrm{\ensuremath{-}}1)/2}$ for n even.