Quantum key distribution using multilevel encoding - art. no. 012306

In this article, protocols for quantum key distribution based on encoding i n higher dimensional systems in N-dimensional Hilbert space are proposed. W e extend the original Bennett-Brassard protocol using two complementary bas es and two-dimensional states to M mutually complementary bases and N ortho gonal vectors in each base. We study the mutual information between the leg itimate parties and the eavesdropper and the error rate by considering vari ous incoherent eavesdropping attacks as a function of the dimension of the Hilbert space.