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
