Towards multi-state based computing using quantum-dot cellular automata

In this article we present an extended quantum-dot cellular automaton (QCA) cell. The extension is mainly focused on the enlargement of the range of possible states of a single QCA cell. In a QCA cell the electrons, owing to electrostatic repulsion, align along one of the two diagonal configurations that correspond to their maximal spatial separation. This gives the QCA cell the ability to encode two states or two logic values (0 and 1). By extending the QCA cell with four additional quantum dots we introduce the extended QCA (EQCA) cell and analyse its behaviour. Our approach is based on the semi-classical modelling approach. Using a special interpretation of electron configurations in the EQCA, the range of possible states is increased from two to three, which gives the EQCA cell the ability to encode the logic values (0, 1 2 and 1). In our opinion the main benefit of this extension is the possibility for introducing “richer” processing and data storage capabilities without an increase in space requirements.