Understanding entanglement sudden death through multipartite   entanglement and quantum correlations
  The effect of Entanglement Sudden Death (ESD) can arise when entangling interactions convert purely bipartite entangled states into more generally entangled states. As a result, ESD can also be seen as a function of partitioning of the system, not just of time, as the system partitioning defines different (multipartite) entanglement classes. Computing both geometric entanglement hierarchies and the generalization of concurrence allows one to demonstrate that different methods of analysing quantum correlations provide both qualitative and quantitatively different descriptions of two commonly cited examples of ESD. These results follow directly from the inequivalence of entanglement and quantum correlations, the later of which can exist in a state without the former. 
Jared H. Cole