Ames Summer 97 Workshop on Device Technology -- QCA -I
One interesting possibility for a future logic system is "quantum dot cellular automata", abbreviated QCA.
Wolfgang Porod of the University of Notre Dame gave a talk on these devices at Ames workshop. His group has proposed configurations of cells, each of which is a collection of five electron sites arranged in an X, with two free electrons within the cell.
According to their studies, configurations of these cells can propagate signals, invert signals, form majority vote logic, and thus can be formed to produce practical devices.
The devices are semi-classical, semi-quantum, in that interactions within a cell can involve quantum tunneling, but interactions between cells involve only classical electromagnetic effects.