  We present a novel method for efficient sorting of photons prepared in states
of orbital angular momentum (OAM) and angular position (ANG). A log-polar
optical transform is used in combination with a holographic beam-splitting
method to achieve better mode discrimination and reduced cross-talk than
reported previously. Simulating this method for 7 modes, we have calculated an
improved mutual information of 2.43 bits/photon and 2.29 bits/photon for OAM
and ANG modes respectively. In addition, we present preliminary results from an
experimental implementation of this technique. This method is expected to have
important applications for high-dimensional quantum key distribution systems.
