Heralded quantum memory for single-photon polarization qubits
  We propose a scheme to implement a heralded quantum memory for single-photon polarization qubits with a single atom trapped in an optical cavity. In this scheme, an injected photon only exchanges quantum state with the atom, so that the heralded storage can be achieved by detecting the output photon. We also demonstrate that the scheme can be used for realizing the heralded quantum state transfer, exchange and entanglement distribution between distant nodes. The ability to detect whether the operation has succeeded or not is crucial for practical application. 
G. W. Lin, X. B. Zou, X. M. Lin, and G. C. Guo