k-separability criterion of mixed multipartite quantum states
Ting Gao, Yan Hong
Abstract
The $k$-separability of mixed $n$-partite ($n\geq 3$) quantum states is mainly discussed in this paper. We obtain practical $k$-separability criteria to identify $k$-nonseparable mixed multipartite states in arbitrary dimensional quantum systems and detect genuine $n$-partite entanglement ($k=2$) and entanglement ($k=3$) which have previously not been identified. No optimization or eigenvalue evaluation is needed, our criteria can be evaluated by simple computations involving components of the density matrix and can be implemented in today's experiments.