Berlin 2008 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 11: Superconductivity: Tunneling, Josephson Junctions, SQUIDs
TT 11.8: Talk
Monday, February 25, 2008, 17:30–17:45, H 3010
Josephson current through a single Anderson impurity coupled to BCS leads — •Christoph Karrasch1, Akira Oguri2, and Volker Meden3 — 1Institut für Theoretische Physik, Universität Göttingen, D-37077 Göttingen, Germany — 2Department of Material Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan — 3Institut für Theoretische Physik A, RWTH Aachen, D-52056 Aachen, Germany
We investigate the Josephson current ⟨ J(φ)⟩ through a quantum dot embedded between two superconductors showing a phase difference φ. The system is modeled as a single Anderson impurity coupled to BCS leads, and the functional and the numerical renormalization group frameworks are employed to treat the local Coulomb interaction U. We reestablish the picture of a quantum phase transition occurring if the ratio between the Kondo temperature TK and the superconducting energy gap Δ or, at appropriate TK/Δ, the phase difference φ or the impurity energy is varied. We present accurate zero- as well as finite-temperature T data for the current itself, thereby settling a dispute raised about its magnitude.