Separability and entanglement of quantum states based on covariance matrices
Ming Li, Shao-Ming Fei, Zhi-Xi Wang · Journal of Physics A Mathematical and Theoretical · 2008
We investigate the separability of quantum states based on covariance matrices. Separability criteria are presented for multipartite states. The lower bound of concurrence proposed in Vicente (2007 Phys. Rev. A 75 052320) is improved by optimizing the local orthonormal observables.