Dresden 2014 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 23: Quantum Chaos
DY 23.1: Vortrag
Mittwoch, 2. April 2014, 15:00–15:15, ZEU 146
Spectral properties of microwave graphs with absorption — Markus Allgeier1, Stefan Gehler1, Sonja Barkhofen1,3, Ulrich Kuhl1,2, and •Hans-Jürgen Stöckmann1 — 1Fachbereich Physik, Universität Marburg — 2Université de Nice Sophia-Antipolis, Nice, France — 3Fachbereich Physik, Universität Paderborn
The influence of absorption on the spectra of microwave graphs has been studied experimentally. The microwave networks were made up of coaxial cables and T junctions. First, absorption was introduced attaching a 50 Ohm load to an additional vertex for graphs with and without time-reversal symmetry. The resulting level spacings distributions were compared with a generalization of the Wigner surmise in the presence of open channels proposed recently by Poli et al. [1]. A good agreement was found using an effective coupling parameter. Secondly, absorption was introduced along one individual bond via a variable microwave attenuator, and the influence of absorption on the length spectrum was studied. The peak heights in the length spectra corresponding to orbits avoiding the absorber were found to be independent of the attenuation, whereas the heights of peaks belonging to orbits passing the absorber once or twice showed the expected decrease with increasing attenuation.
[1] Poli et al., Phys. Rev. Lett. 108, 174101 (2012)