  We examine a building block for logic devices in which the positions of
superconducting vortices in coupled elongated antidots provide the elementary
logic states of 0 and 1. We show analytically and through simulation the
maximum operating frequency of a pair of antidots as a function of antidot
spacing and elongation. At finite temperatures, a signal can propagate through
a series of identically shaped antidots with correctly chosen spacing, with an
exponential distribution of switching times for the signal to move over by one
antidot.
