Bell’s theorem without inequalities

TLDR

Perfect correlations refer to arrangements where measuring one particle predicts with certainty the outcome of another particle in the system. The authors illustrate the approach using spin‑correlation and multiparticle interferometry examples with three‑ and four‑particle arrangements, both in thought experiments and real experiments. The study shows that the EPR premises are inconsistent for systems of at least three particles, revealing a stronger contradiction with quantum mechanics than Bell’s inequality for two‑particle perfect correlations.

Abstract

It is demonstrated that the premisses of the Einstein–Podolsky–Rosen paper are inconsistent when applied to quantum systems consisting of at least three particles. The demonstration reveals that the EPR program contradicts quantum mechanics even for the cases of perfect correlations. By perfect correlations is meant arrangements by which the result of the measurement on one particle can be predicted with certainty given the outcomes of measurements on the other particles of the system. This incompatibility with quantum mechanics is stronger than the one previously revealed for two-particle systems by Bell’s inequality, where no contradiction arises at the level of perfect correlations. Both spin-correlation and multiparticle interferometry examples are given of suitable three- and four-particle arrangements, both at the gedanken and at the real experiment level.