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Abstract
Quantum cellular automata (QCA) have been used widely to digital circuits and systems. QCA technology is a promising alternative to CMOS technology. It is attractive due to its fast speed, small area and low power consumption, higher scale integration, higher switching frequency than transistor based technology. Various QCA circuits, Multivalve Reversible Logic (MVL) Circuit as well as Feynman gate have been proposed in this paper. The QCA offers a novel electronics paradigm for information processing and communication. In this paper, a Feynman gate circuit is proposed based on QCA logic gates: the Maj3, Maj AND gate, Maj OR based on QCA logic gates. The proposed circuit is a remising future in constructing of nano-scale low power consumption information processing system and can stimulate higher digital applications in QCA.
Keywords: Quantum Cellular Automata, QCA Logic Gates, Feynman gate in QCA.
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1. Introduction
QCA is a novel emerging technology in which logic states are not stored as voltage levels, but rather the position of individual electrons. Conceptually, QCA represents binary information by utilizing a bitable charge configuration rather than a current switch. A QCA cell can be viewed as a set of four "dots" that are positioned at the corners of a square. A quantum dot is a site in a cell in which a charge can be localized. The cell contains two extra mobile electrons that can quantum mechanically tunnel between dots, but not cells. In the ground state and in the absence of external electrostatic perturbation [1], the electrons are forced to the corner positions to maximize their separation due to Coulomb repulsion. As shown in Figure 1, the two possible charge configurations are used to represent binary "0" and "1". Note that in the case of an isolated cell, the two polarization states are energetically degenerate. However the presence of other charges (neighbor cells) breaks the degeneracy and one polarization state becomes the cell ground state [1]. Polarization P measures the extent to which the charge distribution is aligned along one of the diagonal axes. If the charge density on dot i is ρi, then the polarization is defined as [2, 3],
...(1)
The tunneling between dots implies that ρi may not be integers as polarization values....