Regensburg 2007 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 27: Quantum chaos III

DY 27.4: Vortrag

Donnerstag, 29. März 2007, 12:00–12:15, H2

Breakdown of retracing in Andreev eigenstates — •Florian Libisch, Stefan Rotter, and Joachim Burgdörfer — Vienna University of Technology, Wiedner Hauptstraße 8-10, Vienna, Austria, EU

Modern manufacturing techniques of semiconductor devices allow the study of single electrons confined to two-dimensional cavities, with linear dimension of the order of a micrometer and below. Such devices are typically referred to as "quantum billiards". Replacing part of the hard wall of the billiard by a superconductor (S) gives rise to coherent scattering of an incoming electron into an outgoing hole. This process, generally known as Andreev reflection, connects the electron and hole degrees of freedom. Classically, the hole emitted by the S-boundary follows the time-reversed path of the electron. At its next contact with the superconductor the hole is converted back into an electron, thereby forming a periodic electron-hole orbit. As a consequence, a semiclassical model based on Andreev retroreflection predicts the electron- and hole eigenstates to mirror each other.

We explicitly calculate the quantum mechanical eigenstates of Andreev billiards, whose classical counterparts feature regular as well as chaotic dynamics. By comparing the wave functions for holes and electrons, the degree of quantum-classical correspondence of the dynamics can be probed. We find eigenstates whose electron and hole components feature qualitatively different patterns, marking the influence of purely quantum mechanical effects.

Supported by FWF Grant No. FWF-P17359.