Three-tangle rate controlled by local operation

Abstract

Since local unitary operations do not change any entanglement measures, to manipulate the distribution of multipartite entanglement, non-local unitary operations should be required. Given a three-qubit system, we study the change of three-tangle under bipartite unitary evolution. We find, once the form of a bipartite interaction is fixed, the changing rate of three-tangle depends on additional single-qubit unitary operations. Furthermore, we give an explicit definition of the three-tangle rate controlled by local operations. By taking advantage of this three-tangle rate, we discuss three examples.