Phase diffusion and charging effects in Josephson junctions
Fakultät für Physik, Albert-Ludwigs-Universität, Hermann-Herder-Straße 3, D-79104 Freiburg, Germany
2 Institut für Physik, Universität Augsburg, Universitätsstraße 1, D-86135 Augsburg, Germany
3 Fachbereich Physik, Martin-Luther-Universität, Selkestraße 9E, D-06099 Halle, Germany
Accepted: 17 September 1998
The supercurrent of a Josephson junction is reduced by phase diffusion. For ultrasmall capacitance junctions the current may be further decreased by Coulomb blockade effects. We calculate the Cooper pair current by means of time-dependent perturbation theory to all orders in the Josephson coupling energy and obtain the current-voltage characteristic in closed form in a range of parameters of experimental interest. The results comprehend phase diffusion of the coherent Josephson current in the classical regime as well as the supercurrent peak due to incoherent Cooper pair tunneling in the Coulomb blockade regime.
PACS: 74.50.+r – Proximity effects, weak links, tunneling phenomena, and Josephson effects / 73.23.Hk – Coulomb blockade; single-electron tunneling / 05.40.+j – Fluctuation phenomena, random processes, and Brownian motion
© EDP Sciences, 1998