TITLE:
Defect and Temperature Effects on Complex Quantum-Dot Cellular Automata Devices
AUTHORS:
Mahfuza Khatun, Benjamin D. Padgett, Gabriel A. Anduwan, Ioan Sturzu, Douglas Tougaw
KEYWORDS:
Quantum-dot Cellular Automata; Thermal Effect; XOR; Full Adder; Fault-Tolerant
JOURNAL NAME:
Journal of Applied Mathematics and Physics,
Vol.1 No.3,
September
6,
2013
ABSTRACT: The authors present an
analysis of the fault tolerant properties and the effects of temperature on an
exclusive OR (XOR) gate and a full adder device implemented using quantum-dot cellular automata (QCA) structures. A
Hubbard-type Hamiltonian and the Inter-cellular Hartree approximation have been used
for modeling, and a uniform random distribution has been implemented for the
simulated dot displacements within cells. We have shown characteristic features
of all four possible input configurations for the XOR device. The device
performance degrades significantly as the magnitude of defects and the
temperature increase. Our results show that the fault-tolerant characteristics
of an XOR device are highly dependent on the input configurations. The input
signal that travels through the wire crossing (also called a crossover) in the
central part of the device weakens the signal significantly. The presence of
multiple wire crossings in the full adder design has a major impact on the
functionality of the device. Even at absolute zero temperature, the effect of
the dot displacement defect is very significant. We have observed that the
breakdown characteristic is much more pronounced in the full adder than in any
other devices under investigation.