Classification of Arbitrary Multipartite Entangled States under Local   Unitary Equivalence
  We propose a practical method for finding the canonical forms of arbitrary dimensional multipartite entangled states, either pure or mixed. By extending the technique developed in one of our recent works, the canonical forms for the mixed $N$-partite entangled states are constructed where they have inherited local unitary symmetries from their corresponding $N+1$ pure state counterparts. A systematic scheme to express the local symmetries of the canonical form is also presented, which provides a feasible way of verifying the local unitary equivalence for two multipartite entangled states. 
Jun-Li Li and Cong-Feng Qiao
quant-ph hep-ph math-ph math.MP