Hierarchies of multipartite entanglement for continuous-variable states
  We derive a hierarchy of separability criteria for multi-mode continuous variable systems. They permit to study in a unified way the k-partite entanglement of broad classes of Gaussian and non- Gaussian states. With specific examples we demonstrate the strength of the criteria, and, we discuss their assessment based on data obtained from Gaussian measurements. 
Antonio A. Valido, Federico Levi, and Florian Mintert
quant-ph