Bell’s Theorem without Inequalities and Beyond (Englisch)

Abstract The investigation of the foundations of quantum mechanics has received momentous stimulation when, in 1964, John Bell established his famous theorem1. It is specifically remarkable that Bell’s work not only triggered an enormous amount of theoretical work, it also gave rise to an extensive series of experiments. Both the discussion and the experiments focussed on the quantum mechanical correlations in two-particle systems. Recently, an extension to systems with more than two particles was found with rather interesting novel properties2. In the present paper we shall firstly point out the similarities and the differences between the two situations and secondly we shall briefly discuss some new aspects concerning entangled states consisting of more than two particles partly by further generalizing the quantum states considered.