Quantum-dot cellular automata: computing with coupled quantum dots

We discuss novel nanoelectronic architecture paradigms based on cells compo sed of coupled quantum-dots. Boolean logic functions may be implemented in specific arrays of cells representing binary information, the so-called qua ntum-dot cellular automata (QCA). Cells may also be viewed as carrying anal ogue information and we outline a network-theoretic description of such qua ntum-dot nonlinear networks (Q-CNN). In addition, we discuss possible reali zations of these structures in a variety of semiconductor systems (includin g GaAs/AlGaAs, Si/SiGe, and Si/SiO2), rings of metallic tunnel junctions, a nd candidates for molecular implementations. We report the experimental dem onstration of all the necessary elements of a QCA cell, including direct me asurement of the charge polarization of a double-dot system, and direct con trol of the polarization of those dots via single electron transitions in d river dots. Our experiments are the first demonstration of a single electro n controlled by single electrons.