Analytic solution for the current-voltage characteristic of two mesoscopic tunnel junctions coupled in series

We present a theoretical analysis for a system composed of two mesoscopic tunnel junctions coupled in series. We show that the current-voltage characteristic for this system can be obtained analytically. The usefulness of the model is demonstrated through the fit of experimental data acquired with a cryogenic (4.2 K) scanning tunneling microscope. A simple extension of the model predicts additional structure in the system characteristics when discrete middle electrode states are present.