Noiseless loss suppression in quantum optical communication
  We propose a protocol for conditional suppression of losses in direct quantum state transmission over a lossy quantum channel. The method works by noiselessly attenuating the input state prior to transmission through a lossy channel followed by noiseless amplification of the output state. The procedure does not add any noise hence it keeps quantum coherence. We experimentally demonstrate it in the subspace spanned by vacuum and single-photon states, and consider its general applicability. 
Michal Micuda, Ivo Straka, Martina Mikova, Miloslav Dusek, Nicolas J.   Cerf, Jaromir Fiurasek, Miroslav Jezek
quant-ph