Generation of Multipartite Ionic Entangled States only by Single-Qubit Measurements via Linear Optical Elements

We propose a scheme for generation of multipartite ionic Greenberger--Horne--Zeilinger (GHZ) states only by single-qubit measurements. Our scheme not only does not need joint measurements but also avoids the difficulty of synchronizing the arrival time of the two scattered photons, which is faced by the previous schemes. Therefore our entanglement generation scheme canbe implemented more easily than the schemes based on atomic interference in experiment.