A Computable Criterion for Partial Entanglement in Continuous Variable   Quantum Systems
  A general and computable criterion for k-(in)separability in continuous multipartite quantum systems is presented. The criterion can be experimentally implemented with a finite and comparatively low number of local observables. We discuss in detail how the detection quality can be optimised. 
Andreas Gabriel, Marcus Huber, Sasa Radic and Beatrix C. Hiesmayr
quant-ph