Entanglement dynamics of two-qubit system in different types of noisy   channels
  In this paper, we study entanglement dynamics of a two-qubit extended Werner-like state locally interacting with independent noisy channels, i.e., amplitude damping, phase damping and depolarizing channels. We show that the purity of initial entangled state has direct impacts on the entanglement robustness in each noisy channel. That is, if the initial entangled state is prepared in mixed instead of pure form, the state may exhibit entanglement sudden death (ESD) and/or be decreased for the critical probability at which the entanglement disappear. 
C. J. Shan, J. B. Liu, W. W. Cheng, T. K. Liu, Y. X. Huang, H. Li