Quantum Dot Cellular Automata: A New Paradigm for Digital Design
Abstract
Quantum Dot Cellular Automata (QCA) is a newly developed paradigm for digital design,
which holds the potential as possible alternative to the present Complementary Metal
Oxide Semi‐Conductor (CMOS) technology. After surviving for nearly five decades, the
scaling of CMOS is finally reaching its limits. The asperities are not only seen from the
physical and technological viewpoint but also from the material and economical
perspectives. With no more scaling possible, there is a need to look for promising
alternatives to continue with the nano size/scale computations and to hold on to the
Moore’s law. QCA offers a breakthrough required for the fulfilment of certain lacking
aspects of CMOS technology in the nano regime. QCA is a technology that involves no
current transfer but works on electronic interaction between the cells. The QCA cell
basically consists of quantum dots or metal islands separated by certain distance and the
entire transmission of information occurs via the interaction between the electrons
localized in the potential wells. Since the technology is new and in a premature phase, a
huge scope lies ahead of the researchers to investigate and make QCA design a reality. In
this paper the QCA technology is reviewed with sufficient focus on basic concepts,
implementations and information flow. The various building blocks in QCA are
discussed and their working on the basis of physical laws is explained. This paper forms
the basis for further complex digital designing in QCA.