Thermal effect in quantum-dot cellular automata

We present a theoretical study of thermal effect in quantum-dot cellular automata (QCA). A quantum statistical model has been introduced to obtain the thermal average of polarization of a QCA cell. We have studied the thermal effect on an inverter, a majority gate and planar arrays of different sizes. The theoretical analysis has been approximated for a two-state model where the cells are in any one of the two possible eigenstates of the cell Hamiltonian. Hence, only the ±1 polarization values are taken into account for the statistical analysis. A numerical computational model has been developed to obtain all possible configurations of the cells in an array. In general, the average polarization of each cell decreases with temperature as well as with the distance from the driver cells. We have found the temperatures for thermal breakdown. The results demonstrate the critical nature of temperature dependence for the operation of QCA.