High temperature anomaly of the conductance of a tunnel junction

The linear conductance of a tunnel junction in series with an ohmic resistor is determined in the high temperature limit. The tunneling current is treated nonperturbatively by means of path integral techniques. Due to quantum effects the conductance is smaller than the classical series conductance. The reduction factor is found to be nonanalytic in the environmental resistance for vanishing resistance. This behavior is a high temperature manifestation of the Coulomb blockade effect.