Influence of Atmospheric Turbulence on Optical Communications using   Orbital Angular Momentum for Encoding
  We describe an experimental implementation of a free-space 11-dimensional communication system using orbital angular momentum (OAM) modes. This system has a maximum measured OAM channel capacity of 2.12 bits/photon. The effects of Kolmogorov thin-phase turbulence on the OAM channel capacity are quantified. We find that increasing the turbulence leads to a degradation of the channel capacity. We are able to mitigate the effects of turbulence by increasing the spacing between detected OAM modes. This study has implications for high-dimensional quantum key distribution (QKD) systems. We describe the sort of QKD system that could be built using our current technology. 
Mehul Malik, Malcolm O'Sullivan, Brandon Rodenburg, Mohammad   Mirhosseini, Jonathan Leach, Martin P. J. Lavery, Miles J. Pa...
quant-ph physics.optics