WAVE-PROPAGATION THROUGH DISORDERED MEDIA AND UNIVERSAL CONDUCTANCE FLUCTUATIONS

Using the many-channel approximation to Landauers formula and statistical scattering theory, we calculate analytically the average, G», and the variance, var(G), of the conductance of a disordered sample of length L, described by a microscopic random Hamiltonian, and coupled at each end to an ideally conducting lead. We show that the coupling to the leads strongly affects the behavior of G» and var (G) for sample sizes LL0, where L0 is a characteristic length of the order of several tens of the elastic mean free path. For LL0, this coupling becomes unimportant. © 1990 The American Physical Society.