Markovian Classicality from Zero Discord for Bipartite Quantum Systems

TL;DR

This paper investigates the conditions under which bipartite quantum systems exhibit classical behavior with zero discord, providing a formal model and proof that clarify the nature of classicality in open quantum systems.

Contribution

It constructs a formal classical model demonstrating Markovian zero-discord classicality and offers a proof of its sufficient conditions, advancing understanding of quantum-classical transition.

Findings

Zero-discord classicality can be formally modeled in Markovian bipartite systems.

A sufficient condition for the existence of Markovian zero-discord classicality is established.

The results highlight the complexity of defining classicality in open quantum systems.

Abstract

Modern quantum information theory provides new tools for investigating the decoherence-induced "classicality" of open quantum systems. Recent observation that almost all quantum states bear non-classical correlations [A. Ferraro {\it et al}, Phys. Rev. A {\bf 81}, 052318 (2010)] distinguishes the zero-discord classicality essentially as a pathology of the Markovian bipartite-systems realm. Nevertheless, we formally construct such a classical model and its variant that represents a matter-of-principle formal proof, i.e. a sufficient condition for the, otherwise not obvious, existence of the Markovian zero-discord classicality. A need for the more elaborate and more systematic search for the alternative such models reveals we are still learning about the very meaning of "classicality" in the realm of open quantum systems.