Multipartite invariant states. I. Unitary symmetry
Dariusz Chruściński, Andrzej Kossakowski · Physical Review A · 2006
We propose a natural generalization of bipartite Werner and isotropic states to multipartite systems consisting of an arbitrary even number of $d$-dimensional subsystems (qudits). These generalized states are invariant under the action of local unitary operations. We study basic properties of multipartite invariant states and present necessary and sufficient separability criteria.