Title

Cellular Automata Rules for Quantum-Dot Cellular Automata

Publication Date

8-2001

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Computer Science

Department

Computer Science

Major Advisor

John C. Lusht

Abstract

Some new device architectures have been proposed that are based on the idea of devices that operate like cellular automata. Operation of cellular automata is based on local interactions; devices based on this paradigm would have much simpler interconnect requirements than conventional devices. One particular device of this type which has been investigated in great detail is the quantum-dot cellular automata. These devices have properties that if implement able would be useful for a new generation of digital circuits. Although many investigations of quantum-dot cellular automata have been reported, there have been no published studies of cellular automata with the same behavior.

This thesis investigates several possible sets of cellular automata rules that could be used to represent quantum-dot cellular automata. Both empirical rules that implement the qualitative arguments that are useful for describing the operation of quantum-dot cellular automata and enumerated rules which are determined from a classical calculation of the Coulomb energy for each possible configuration have been investigated. Interaction over one and two intercellular distances have been investigated. Most of the wire and gate configurations that have been suggested for quantum-dot cellular automata were tested using these rules.

The conclusions reached from this study are that only arrangements of cells which meet certain conditions behave as desired for most of the rule sets that were tested. Arrangements of cells for which any particular cell has no neighbors which are adjacent to each other are well behaved. Arrangements of cells with bends and crosses tend to either have incorrect outputs or be unstable for some of possible inputs. These results suggest that quantum-dot cellular automata based on Coulomb effects will need something other than strictly local interactions if they are to operate correctly.

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