CONDUCTANCE FLUCTUATIONS IN A METALLIC WIRE INTERRUPTED BY A TUNNEL JUNCTION

The conductance fluctuations of a metallic wire which is interrupted b y a small tunnel junction has been explored experimentally. In this sy stem, the bias voltage V, which drops almost completely inside the tun nel barrier, is used to probe the energy dependence of conductance flu ctuations due to disorder in the wire. We find that the variance of th e fluctuations is directly proportional to V. The experimental data ar e consistently described by a theoretical model with two phenomenologi cal parameters: the phase breaking time at low temperatures and the di ffusion coefficient.