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DY: Fachverband Dynamik und Statistische Physik

DY 40: Poster - Quantum Systems/ Stat. Phys./ Diffusive Process

DY 40.4: Poster

Donnerstag, 3. April 2014, 17:00–19:00, P3

Experiments with Superconducting Microwave Billiards — •Barbara Dietz, Maksim Miski-Oglu, Tobias Klaus, Christopher Cuno, and Achim Richter — Institut für Kernphysik, TU-Darmstadt, Schlossgartenstr. 9, D-64298 Darmstadt

We present experimental results on spectral properties of Dirac billiards simulating graphene billiards. They consist of a photonic crystal enclosed in a microwave billiard. Here we use the analogy between the associated scalar Helmholtz equation and the Schrödinger equation and the fact that the peculiar properties of graphene are solely due to the symmetry properties of its hexagonal lattice structure. We will present results on the spectral properties and length spectra of periodic orbits that were obtained in high precision experiments with superconducting Dirac billiards. Furthermore we determined the density of states with an unprecedented accuracy and investigated the effect of edge states on its features. It exhibits two sharp peaks at the frequencies of the van Hove singularities. There, a topological transition from the relativistic Dirac regime to the non-relativistc Schrödinger regime takes place which can be identified with a neck-disrupting Lifshitz and with an excited state quantum phase transition. The theoretical considerations are corroborated by experimental results on the features of the density of states.

*Supported by the Deutsche Forschungsgemeinschaft (DFG) within the Collaborative Research Center SFB634.