Regensburg 2010 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 19: Quantum Chaos

DY 19.12: Talk

Wednesday, March 24, 2010, 17:15–17:30, H38

The density of states of chaotic Andreev Billiards — •Thomas Engl, Jack Kuipers, and Klaus Richter — Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg,Germany

Quantum cavities, like quantum dots, have markedly different properties depending on whether their classical counterparts are chaotic or not. Connecting a superconductor to such a dot leads to remarkable effects, most notably the appearance of a hard gap in the excitation spectrum of chaotic systems. Andreev billiards are interesting examples of structures built by superconductors connected to a normal metal, and each time an electron hits the superconducting part it is retro-reflected as a hole (and vice-versa).

Using a semiclassical framework for systems with chaotic dynamics, we show how this reflection, along with the interference due to subtle correlations between the classical paths of electrons and holes inside the system, are ultimately responsible for this phenomenon. Furthermore, we are able to see how a magnetic field inside the system or phases inside the superconductor can remold and eventually suppress the gap.