Nonlocal correlations for manifold quantum systems: Entanglement of   two-spin states
  In this paper, we study the bipartite entanglement of spin coherent states in the case of pure and mixed states. By a proper choice of the subsystem spins, the entanglement for large class of quantum systems is investigated. We generalize the result to the case of bipartite mixed states using a simplified expression of concurrence in Wootters' measure of the bipartite entanglement. It is found that in some cases, the maximal entanglement of mixed states in the context of $su(2)$ algebra can be detected. Our observations may have important implications in exploiting these states in quantum information theory. 
K. Berrada, A. Mohammadzade, S. Abdel-Khalek, H. Eleuch and S. Salimi
quant-ph math-ph math.MP