Markovian Classicality from Zero Discord for Bipartite Quantum Systems

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.