Experimental detection of multipartite entanglement using witness operators

Phys Rev Lett. 2004 Feb 27;92(8):087902. doi: 10.1103/PhysRevLett.92.087902. Epub 2004 Feb 26.

Abstract

We present the experimental detection of genuine multipartite entanglement using entanglement witness operators. To this aim, we introduce a canonical way of constructing and decomposing witness operators so that they can be directly implemented with present technology. We apply this method to three- and four-qubit entangled states of polarized photons, giving experimental evidence that the considered states contain true multipartite entanglement.