The origin of quantum discord
In 2001 Ollivier and Zurek, and Henderson and Vedral independently conclude that entanglement does not take into account all nonclassical correlations. To define a new quantity, for bipartite systems, which not only contains entanglement, but also other truly quantum correlations, they introduce quantum discord. Quantum discord is defined as the difference between two expressions for quantum mutual information. One of them consists of a measurement process in one of the subsystems, which makes the difference of quantum systems. We will make a brief review of classical information to understand how the discord is defined mathematically and then we will see some of their basic properties.
Host: Charles Clark