STATISTICAL SIGNIFICANCE OF CONDUCTANCE QUANTIZATION

Recent experiments on atomic-scale metallic contacts have shown that t he quantization of the conductance appears clearly only after the aver age of the experimental results. Motivated by these results we have an alyzed a simplified model system in which a narrow neck is randomly co upled to wide ideal leads, both in absence and presence of time revers al invariance. Based on random matrix theory we study analytically the probability distribution for the conductance of such system. As the w idth of the leads increases the distribution becomes sharply peaked cl ose to an integer multiple of the quantum of conductance. Our results suggest a possible statistical origin of conductance quantization in a tomic-scale metallic contacts. [S0163-1829(98)04604-9].