Evolution of the quantized ballistic conductance with increasing disorder in narrow-wire arrays

We study the two-terminal Landauer conductance averaged over a parallel array of disordered narrow wires as the Fermi energy and length of the disordered region are varied. As disorder in the wires is increased, so that quantum diffusion becomes the dominant electron-transport mechanism, we find numerically that the quantized conductance steps characteristic of ballistic transport evolve into conductance drops after each new subband is populated. Consistent with this result, the electron localization length decreases above each new subband. Adding attractive scatterers to the wires strongly modifies these results due to ``quasidonor levels'' forming in the impurities.