Geometric extension of Clauser-Horne inequality to more qubits

Abstract

We propose a geometric multiparty extension of Clauser-Horne (CH) inequality. The standard CH inequality can be shown to be an implication of the fact that statistical separation between two events, A and B, defined as P (A circle plus B), where A circle plus B = (A - B) boolean OR (B - A), satisfies the axioms of a distance. Our extension for tripartite case is based on triangle inequalities for the statistical separations of three probabilistic events P (A circle plus B circle plus C). We show that Mermin inequality can be retrieved from our extended CH inequality for three subsystems in a particular scenario. With our tripartiteCH inequality, we investigate quantum violations by GHZ-type and W-type states. Our inequalities are compared to another type, so- called N-site CH inequality. In addition we argue how to generalize our method for more subsystems and measurement settings. Our method can be used to write down several Bell-type inequalities in a systematic manner.