The effective protection protocol of single photon state from photon   loss and decoherence
  We design an effect protocol for protecting the single-photon entanglement from photon loss and decoherence. The protocol only requires some auxiliary single photons and the linear optical elements. By operating the protocol, the photon loss can be effectively decreased and the less entangled single photon state can be recovered to the maximally entangled state with some probability. Moreover, the polarization information encoded in the single photon state can be perfectly contained. The protocol can be realized under current experimental condition. As the single photon entanglement is quite important in quantum communication, this protocol may be useful in current and future quantum information processing. 
Lan Zhou, Yu-Bo Sheng
quant-ph