Scheme for the preparation of macroscopicW-type state of atomic ensembles in cavity QED coulped with optical fibers

We propose a potentially practical scheme to generate macroscopic W-type state of N atomic ensembles in cavity QED system consisting of N atomic ensembles trapped in N single-mode cavities connected by (N ? 1) optical fibers. We show that the N-qubit W-type state of atomic ensembles can be realized with high success probabilities if the coulping strength of the cavity-fiber is much stronger than that of cavity-atom. We also show that both the growth of atomic number in each ensemble and the increase of the number of atomic ensembles can diminish the detrimental influence from dissipative processes. This idea provides a scalable way to an atomic-ensemble-based quantum network, which is plausible with current available technology.