Research Article

Weak classicality in coupled N-level quantum systems

¹ Department of Physics and Computer Science, Dayalbagh Educational Institute, Agra, Uttar Pradesh 282005, India
² Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India

^a e-mail: radha.pyari@gmail.com
^b e-mail: vravi@physics.iitd.ac.in

Received: 1 January 2019
Received in final form: 4 April 2019
Published online: 11 June 2019

Abstract

The notion of “weak classical limit” for coupled N-level quantum systems as N → ∞ is introduced to understand the precise sense in which one attains classicality. There exists proofs that a system becomes classical at large N [1, 2]. On the other hand, it is known that non-locality and entanglement, the two hallmarks of non-classicality, thrive even as N → ∞. 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.