Abstract

We propose an experimentally feasible scheme to prepare tripartite continuous-variable entanglement with the spatial degrees of freedom of photons. The scheme relies on postselection upon the state obtained when one photon of an entangled pair produced by spontaneous parametric down-conversion interferes with a single photon on a 50: 50 beam splitter. We show that the presence of genuine tripartite entanglement can be detected by the van Loock-Furusawa criterion.