We discuss simple models which appear to account quantitatively for the anomalous low-voltage resistance $R_0$ observed in small, high-resistance Josephson tunnel junctions. We compare our predictions with both new and previously reported measurements. At high temperatures $R_0$ is fit well by a model based on thermal activation. At low temperatures, our results are in good agreement with a model based on theoretical predictions for macroscopic quantum tunneling rates in the underdamped limit. The crossover temperature between the two regimes is dependent on magnetic field, as expected.

• Received 4 August 1989

DOI:https://doi.org/10.1103/PhysRevB.40.11370