Weak Classicality in Coupled N-Level Quantum Systems

Abstract

The notion of `weak classical limit' for coupled N-level quantum systems as N -> infinity is introduced to understand the precise sense in which one attains classicality. There exist proofs that a system becomes classical at large N. On the other hand, it is known that non-locality and entanglement, the two hallmarks of non-classicality, thrive even as N -> infinity. We reconcile these results in this paper by showing that so called classicality is not so much an inherent property of the system, as it is a consequence of limited experimental resources. Our focus is largely on non-locality, for which we study the Bell-CHSH and CGLMP inequalities for N-level systems.