Improved Separability Criteria Based on Bloch Representation of Density   Matrices
  The correlation matrices or tensors in the Bloch representation of density matrices are encoded with entanglement properties. In this paper, based on the Bloch representation of density matrices, we give some new separability criteria for bipartite and multipartite quantum states. Theoretical analysis and some examples show that the proposed criteria can be more efficient than the previous related criteria. 
Shu-Qian Shen, Juan Yu, Ming Li and Shao-Ming Fei
quant-ph