Robust and scalable scheme to generate multipartite atom–photon and atom–atom entangled W states by interference

A robust and scalable scheme for generating atom–photon and atom–atom entangled W states is proposed by using the interference effect of the polarized photons leaking out of the spatially separated cavities. Each of the atoms is trapped separately in a remote optical cavity, and the possible spontaneous channels induced by the excited atoms lead to the coherent superposition between atoms and photon, which is an important step toward long-distance and long-range quantum networking with individual atoms. The scalability is ensured in the sense that an arbitrarily large multiqubit atom–photon and atom–atom entangled W state can be generated with certain success probabilities.