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TT: Fachverband Tiefe Temperaturen

TT 54: SC: Heterostructures, Andreev Scattering, Proximity Effect

TT 54.6: Talk

Thursday, March 17, 2011, 16:45–17:00, HSZ 301

Controlling the Conductance and Thermopower of Chaotic Quantum Dots — •Thomas Engl, Jack Kuipers, and Klaus Richter — Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg, Germany

Transport through quantum cavities, like quantum dots, has raised much interest in physics in recent decades. When attaching superconductors to the cavity, these transport properties are substantially changed, known to be caused by Andreev reflection on the interface between the normal region and the superconductor.

Using a semiclassical framework for ballistic systems, so called Andreev billiards with chaotic dynamics, we show how Andreev reflection along with the interference due to subtle correlations between the classical paths of electrons and holes inside the system affects the conductance of the system and see how these combined cause large quantum corrections to the conductance like its reduction by a phase difference between the superconductors. Furthermore we show that the thermopower requires an asymmetry with respect to an exchange of the superconducting leads in order to be nonzero. Moreover, we are able to see what happens if the temperature is increased or a magnetic field is applied.