Eur. Phys. J. C (2007) 50: 73-79
https://doi.org/10.1140/epjc/s10052-006-0199-x

Regular Article - Theoretical Physics

Nonlocality and entanglement in a strange system

Institute for Theoretical Physics, University of Vienna, Boltzmanngasse 5, 1090, Vienna, Austria

^* e-mail: Beatrix.Hiesmayr@univie.ac.at

Received: 13 September 2006
Revised: 16 November 2006
Published online: 6 February 2007

Abstract

We show that the relation between nonlocality and entanglement is subtler than one naively expects. In order to do this we consider the neutral kaon system – which is oscillating in time (particle–anti-particle mixing) and decaying – and describe it as an open quantum system. We consider a Bell–CHSH inequality and show a novel violation for non-maximally entangled states. Considering the change of purity and entanglement in time we find that, despite the fact that only two degrees of freedom at a certain time can be measured, the neutral kaon system does not behave like a bipartite qubit system.