What has a symmetry violation in particle physics to do with non-locality?

Abstract

Particle physics has become an interesting testing ground for fundamental questions of quantum mechanics (QM). The massive meson-antimeson systems are specially suitable as they offer a unique laboratory to test various aspects of particle physics (\(\cal{CP}\) violation, \(\cal{CPT}\) violation, ...) as well to test the foundations of QM (local realistic theories versus QM, Bell inequalities, decoherence effects, quantum marking and erasure concepts, ...). We focus here on a surprising connection between the violation of a symmetry in particle physics –the \(\mathcal{CP}\) symmetry (\(\cal{C}\)=charge conjugation, \(\cal{P}\)=parity)– and non-locality. This is achieved via Bell inequalities which discriminate between local realistic theories and QM. Further we present a decoherence model which can be tested by accelerator experiments at the DAΦNE (Italy) and at the KEK-B machine (Japan). We show that there is a simple connection between a decoherence parameter and different measures of entanglement, i.e., entanglement of formation and concurrence. In this way the very basic mathematical and theoretical concepts about entanglement can be confronted directly with experiments. Similar decoherence models can also be tested for entangled photon systems and single neutrons in an interferometer.