We study the efficiency of adaptive optics (AO) correction for the free-space propagation of entangled photonic orbital-angular-momentum (OAM) qubit states, to reverse moderate atmospheric turbulence distortions. We show that AO can significantly reduce crosstalk to modes within and outside the encoding subspace and thereby stabilize entanglement against turbulence. This method establishes a reliable quantum channel for OAM photons in turbulence, and enhances the threshold turbulence strength for secure quantum communication at least by a factor two.
@article{arxiv.1709.09887,
title = {Protecting entanglement of twisted photons by adaptive optics},
author = {Nina Leonhard and Giacomo Sorelli and Vyacheslav N. Shatokhin and Claudia Reinlein and Andreas Buchleitner},
journal= {arXiv preprint arXiv:1709.09887},
year = {2018}
}