Topological classification of multipartite entangled states by the hyperdeterminant

We find that the hyperdeterminant $Det A$, related to an entanglement measure (the concurrence, 3-tangle for the 2,3-qubit respectively), is derived from a duality between the entangled states and separable states. In terms of $Det A$ and its singularities, the single copy of multipartite pure entangled states is classified into an onion structure of every closed subset, similarly to the local rank in the bipartite case. This reveals that many inequivalent multipartite entangled states are partially ordered such that entanglement measures like $Det A$ as well as local ranks are needed to distinguish them. In particular, the nonzero $Det A$ distinguishes generic entangled states of the maximal dimension (the outermost class of the onion structure). It suggests that the majority of multipartite entangled states never locally converts to the maximally entangled states in Bell's inequalities even probabilistically in general (e.g., in the $n \geq 4$-qubit), contrary to the widely known bipartite or 3-qubit cases. The classification is also useful for that of mixed states.