Eliminating wire crossings for molecular quantum-dot cellular automata implementation

When exploring computing elements made from technologies other than CMOS, it is imperative to investigate the effects of physical implementation constraints. This paper focuses on molecular Quantum-dot Cellular Automata circuits. For these circuits, it is very difficult for chemists to fabricate wire crossings (at least in the near future). A novel technique is introduced to remove wire crossings in a given circuit to facilitate the self assembly of real circuits - thus providing meaningful and functional design targets for both physical and computer scientists. The technique eliminates all wire crossings with minimal logic gate/node duplications. Experimental results based on existing QCA circuits and other benchmarks are quite encouraging, and suggest that further investigation is needed.