Quantum Coherence Bounds the Distributed Discords

TL;DR

This paper explores the relationship between quantum coherence and discord in bipartite systems, establishing bounds and protocols for distributing quantum correlations using coherence as a resource.

Contribution

It introduces trade-off relations between discord and coherence, and demonstrates that quantum correlations are essential for optimal discord distribution protocols.

Findings

Bound on the increase of discord by coherence

Optimal protocol for discord distribution

Quantum correlations as a key resource

Abstract

Establishing quantum correlations between two remote parties by sending an information carrier is an essential step of many protocols in quantum information processing. We obtain trade-off relations between discords and coherence within a bipartite system. Then we study the distribution of coherence in a bipartite quantum state by using the relations of relative entropy and mutual information. We show that the increase of the relative entropy of discord between two remote parties is bounded by the nonclassical correlations quantified by the relative entropy of coherence between the carrier and two remote parties, providing an optimal protocol for discord distribution and showing that quantum correlations are the essential resource for such tasks.