In quantum information theory, quantum discord is a measure of nonclassical correlations between two subsystems of a quantum system. It includes correlations that are due to quantum physical effects but do not necessarily involve quantum entanglement.
互信息(Mutual Information)是信息论里一种有用的信息度量，它可以看成是一个随机变量中包含的关于另一个随机变量的信息量，或者说是一个随机变量由于已知另一个随机变量而减少的不肯定性。可见 http://wenku.baidu.com/view/4f22344369eae009581bec36.html?re=view
量子不和是从量子互信息的角度来定义的，表示了两种不同表达式之间的差异
Individual (H(X), H(Y)), joint (H(X,Y)), and conditional entropies for a pair of correlated subsystems X, Y with mutual information I(X; Y).
对于量子不和可以作为远程量子资源，或者这种可以用来做量子网络？
https://en.wikipedia.org/wiki/Quantum_discord
原文：http://www.cnblogs.com/guxuemei01/p/4981931.html