Using the many-channel approximation to Landauer’s 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 L≲$L_0$, where $L_0$ is a characteristic length of the order of several tens of the elastic mean free path. For L≫$L_0$, this coupling becomes unimportant.

• Received 27 July 1989

DOI:https://doi.org/10.1103/PhysRevLett.64.583