Near-field turbulence effects on quantum-key distribution

Bounds on average power transfer over a near-field optical path through atmospheric turbulence are used to deduce bounds on the sift and error probabilities of a free-space quantum-key distribution system that uses the Bennett-Brassard 1984 (BB84) protocol. It is shown that atmospheric turbulence imposes at most a modest decrease in the sift probability and a modest increase in the conditional probability of error given that a sift event has occurred.