Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 18: Nanoelectronics I - Quantum Dots, Wires, Point Contacts
TT 18.5: Vortrag
Mittwoch, 28. März 2007, 15:00–15:15, H19
Non-equilibrium Josephson current through interacting quantum dots — •Marco G. Pala1, Michele Governale2, and Jürgen König2 — 1IMEP-MINATEC (UMR CNRS/INPG/UJF), F-38049 Grenoble, France — 2Institut für Theoretische Physik III, Ruhr-Universität Bochum, D-44780 Bochum, Germany
We study transport through a quantum dot weakly coupled to both normal and superconducting leads. To this aim, we generalize a diagrammatic real-time transport theory[1] to account for superconductivity in the leads. In particular, we consider a system consisting of a quantum dot tunnel coupled to one normal and two superconducting leads. A finite voltage can be applied between the normal and the superconducting leads to drive the dot out of equilibrium. The dot is described by a single, spin-degenerate level, with arbitrary Coulomb repulsion U. The tunnel coupling to the superconducting leads induces a coherent superposition of the empty and doubly occupied dot states (proximity effect). In turn, this may mediate a Josephson current between the two superconductors. We find a situation in which the Josephson current is switched on due to the interplay of Coulomb interaction and non-equilibrium in the dot.
[1] J. König, H. Schoeller, and G. Schön, Phys. Rev. Lett. 76, 1715 (1996)