Does The Uncertainty Relation Determine The Quantum State?
  The example of nonpositive trace-class Hermitian operator for which Robertson-Schroedinger uncertainty relation is fulfilled is presented. The partial scaling criterion of separability of multimode continuous variable system is discussed in the context of using nonpositive maps of density matrices. 
Olga V. Man'ko, V.I. Man'ko, G. Marmo, E.C.G. Sudarshan, F. Zaccaria