  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.
