Three-party entanglement from positronium - art. no. 042107

The decay of orthopositronium into three photons produces a physical realiz ation of a pure state with three-party entanglement. Its quantum correlatio ns an analyzed using recent results on quantum information theory, looking for the final state that has the maximal amount of Greenberger, Home, and Z eilinger like correlations. This state allows for a statistical dismissal o f local realism stronger than the one obtained using any entangled state of two spin one-half particles.