  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.

Quantum Physics