Higher-dimensional orbital angular momentum based quantum key   distribution with mutually unbiased bases
  We present an experimental study of higher-dimensional quantum key distribution protocols based on mutually unbiased bases, implemented by means of photons carrying orbital angular momentum. We perform (d+1) mutually unbiased measurements in a classical prepare and measure scheme and on a pair of entangled photons for dimensions ranging from d = 2 to 5. In our analysis, we pay attention to the detection efficiency and photon pair creation probability. As security measures, we determine from experimental data the average error rate, the mutual information shared between the sender and receiver and the secret key generation rate per photon. We demonstrate that increasing the dimension leads to an increased information capacity as well as higher key generation rates per photon up to a dimension of d = 4. 
Mhlambululi Mafu, Angela Dudley, Sandeep Goyal, Daniel Giovannini,   Melanie McLaren, Miles J. Padgett, Thomas Konrad, Franc...
quant-ph