Near-deterministic generation of four-mode W-type entangled coherent states

In this paper, we propose an optical scheme to generate four-mode W-type entangled coherent states (ECSs) in free travelling optical fields by using a single-photon source, coherent state sources, beam splitters, photodetectors and cross-Kerr media. Our scheme consists of a symmetric optical setup in which there are two Mach-Zehnder interferometers in which each arm contains a cross-Kerr medium. We calculate the average fidelity of generated W-type ECSs, the success probability of producing four-mode W-type ECSs and the average fidelity of the generated four-mode W-type ECSs. It is indicated that our protocol is nearly deterministic