Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 33: Superconductivity, Measuring Devices, Matter at Low Temperature: Poster Session

TT 33.58: Poster

Wednesday, March 28, 2012, 15:00–19:00, Poster B

AC Josephson current through quantum dots — •Bastian Hiltscher¹, Michele Governale², and Jürgen König¹ — ¹Theoretische Physik, Universität Duisburg-Essen and CeNIDE — ²School of Chemical and Physical Sciences and MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington

We consider a setup consisting of two superconductors linked by a single-level quantum dot with strong Coulomb repulsion. An AC Josephson current is generated by applying a bias voltage to the superconductors. Our formalism bases on a diagramatic perturbation expansion in tunnel coupling [1], where the quasiparticle states are traced out from the total density matrix and the quantum dot as well as the Cooper pair condensates are treated explicitly. The Coulomb repulsion is taken into account nonperturbatively. We find that the first harmonic dominates the higher ones. Furthermore, we discuss the differences between the AC and the DC Josephson effect.
M. Governale, M. G. Pala, and J. König, PRB 77, 134513 (2008).