Transferring multipartite entanglement among different cavities
  The transfer of quantum entanglement (or quantum coherence) is not only fundamental in quantum mechanics but also important in quantum information processing. We here propose a way to achieve the coherent transfer of $W$-class entangled states of qubits among different cavities. Because no photon is excited in each cavity, decoherence caused by the photon decay is suppressed during the transfer. In addition, only one coupler qubit and one operational step are needed and no classical pulses are used in this proposal, thus the engineering complexity is much reduced and the operation is greatly simplified. We further give a numerical analysis, showing that high-fidelity transfer of a three-qubit $W$ state is feasible within the present circuit QED technique. The proposal can be applied to a wide range of physical implementation with various qubits such as quantum dots, nitrogen-vacancy centers, atoms, and superconducting qubits. 
Qi-Ping Su, Tong Liu, and Chui-Ping Yang
quant-ph