Quantum-Dot Cellular Automata (QCA) is a novel computing paradigm which encodes information in the position of elementary charges, and relies on the charge interactions to enable the transmission and processing of information. The underlying building block of any QCA circuit is the QCA cell, which is constructed with four to six coupled quantum dots and charged with two mobile electrons. The Coulombic interactions between the charges in neighbouring cells provides a basis for the construction of complex computing architectures. In this thesis, we investigate two important aspects of QCA, these are:​ QCA modeling and simulation, and QCA circuit design.

One of the important properties of QCA is that the physical details of the devices can be hidden from the circuit designer. We discuss the details of a design and simulation tool called QCADesigner, which enables the rapid design and simulation of complex circuits. QCADesigner incorporates established quantun mechanical simulation models of QCA cells and interactions and permits the circuit designers to concentrate their efforts on the design aspects and not the details of QCA physics and implementations.

Using QCADesigner, we investigate several important circuits used very frequently in computers including;​ basic logic gates, multiplexers, adders, multipliers, etc. We outline certain considerations that lead to a design flow. As well, we describe an algorithm for determining a minimal majority representation of a Boolean function, an important tool since the majority gate is the basic logic element of QCA. Using simulations, we outline a set of technology criteria that we have found to be essential for the proper operation of our proposed circuits.