Reliability and Defect Tolerance in Metallic Quantum-dot Cellular Automata

The computational paradigm known as quantum-dot cellular automata (QCA) encodes binary information in the charge configuration of Coulomb-coupled quantum-dot cells. Functioning QCA devices made of metal-dot cells have been fabricated and measured. We focus here on the issue of robustness in the presence of disorder and thermal fluctuations. We examine the performance of a semi-infinite QCA shift register as a function of both clock period and temperature. The existence of power gain in QCA cells acts to restore signal levels even in situations where high speed operation and high temperature operation threaten signal stability. Random variations in capacitance values can also be tolerated.