19. Quantum Dot Cellular Automata (QDCA)

For representation of binary information and performing computations on them, cells containing quantum dots at defined locations are used. Tunnel barriers separate the neighboring dots. Under the control of a back plane voltage, electrons can tunnel between dots. But intercell barriers strictly prevent tunneling of electrons across cells. Information is encoded in the form of positions of electrons in the cell. Electrons in each cell interact Coulombically. The cells are also coupled through Coulomb forces between electrons. The utilization of QDCA as a wire, as a majority voter, and for performing logic AND/OR operations is explained. Salient features and applications of the QDCA approach are described. The quantum dot-based architecture is experimentally proven to work in the mKelvin temperature range. This field-coupled nanocomputing model is likely to challenge and succeed the CMOS for room-temperature operation when technological capability develops to the level of easily fabricating quantum dots of molecular size.