Linear Optics Quantum Communication over Long Distances

We propose a feasible scheme for teleporting an arbitrary polarization state or entanglement of photons by requiring only single-photon (SP) sources, simple linear optical elements and SP quantum non-demolition measurements. An unknown SP polarization state can be faithfully teleported either to a duplicate polarization state or to an entangled state. Our proposal can be used to implement long-distance quantum communication in a simple way. The scheme is within the reach of current technology and significantly simplifies the realistc implementation of long-distance high-fidelity quantum communication with photon qubits.