Active Transmission Channels and Universal Conductance Fluctuations

Abstract

The transport through a segment of a disordered system is determined by the eigenvalues of a large random matrix. The effectively independent active transmission channels are associated with these eigenvalues which are closest to unity. A decreasing number of those survives when the system's length increases. They determine the conductance and its fluctuations, which are found to be independent, within broad limits, of the size, disorder and nature of the system. This universality is due to the strong correlations in the spectra of large random matrices, providing a new insight on and generalizing the extremely interesting recent results of Altschuler, Lee and Stone.