EFFECT OF STRAY CHARGE ON QUANTUM CELLULAR-AUTOMATA

We study the operation of quantum cellular automata (QCA) devices in t he presence of stray charge. The operation of linear arrays of QCA cel ls, called binary wires, relies on Coulombic interaction between the c ells, which is affected by the presence of such stray charge. The posi tion of the charge determines whether or not the devices function prop erly, and it is possible to determine the ''forbidden'' region near th e array in which the presence of stray charge causes device failure. W e calculate this forbidden region by directly diagonalizing the Hamilt onian for the system including the stray charge. We find that the QCA binary wire is unaffected by stray charge at a distance greater than t he intercellular repeat distance of the wire.