Multivalued Logic at the Nanoscale

Molecular and nanostructured systems for logic processing are typically characterized by more than two internal states. The implementation of multivalued logic is thus a natural strategy to minimize storing space, to reduce the burden of interconnections and to enhance the complexity of the logic processing. We discuss the application of multivalued logic at the nanoscale by considering different physical implementations of multivalued processing. Unconventional hardware such as molecular electronic states have been used to implement multivalued decision trees and decomposition of logic functions in base five. We discuss an all-optical set-up where the dynamics of molecular states excited by a sequence of laser pulses realizes an unprecedented density of logic processing through the parallelism inherent in the quantum dynamical evolution. Moreover, the search for low energy computing devices that can be interfaced with the conventional CMOS technology led to the design of several multivalued logic schemes in solid state nanostructures. We report in detail a possible implementation of a ternary full-addition in quantum dots embedded in a solid state matrix.