von Neumann measurement-related matrices and the nullity condition for   quantum correlation
  We study von Neumann measurement-related matrices, and the nullity condition of quantum correlation. We investigate the properties of these matrices that are related to a von Neumann measurement. It is shown that these (m^2-1)* (m^2-1) matrices are idempotent, and have rank m-1. These properties give rise to necessary conditions for the nullity of quantum correlations in bipartite systems. Finally, as an example we discuss quantum correlation in Bell diagonal states. 
Ming-Jing Zhao, Teng Ma, Ting-Gui Zhang, and Shao-Ming Fei
quant-ph