Protecting classical-quantum signals in free-space optical channels

Due to turbulence and tracking errors, free-space optical channels involving mobile transceivers are characterized by a signal's partial loss or complete erasure. This work presents an error-correction protocol capable of protecting signal passing through such encoding it with ancillary entangled bipartite state. Beyond its ability offer protection under realistic channel conditions, our has the transmit both quantum state classical symbol using same encoded We show how can improve fidelity transmitted coherent states over wide range losses erasure probabilities relative nonencoded direct transmission. In addition, use non-Gaussian in is considered, showing this increase performance. Finally, we briefly discuss application transmission more complex input states, as multimode states.