Quantum Discord: A Dynamic Approach in Geometric Picture
  We present a dynamic approach to study the quantum discord and classical correlation. By local filtering operation, the evaluation of quantum discord is closely related to quantum channel and channel capacity. As a consequence, the traditional optimization over horizontal-or-vertical von Neumann measurements is replaced by that over horizontal-and-vertical three-element POVM measurement, from which more rigorous results of quantum discord are obtained. 
Mingjun Shi, Fengjian Jiang, Jiangfeng Du
quant-ph