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TT: Fachverband Tiefe Temperaturen

TT 4: Disordered Quantum Systems

TT 4.2: Vortrag

Montag, 16. März 2020, 10:00–10:15, HSZ 204

Electrically Biased Resonators for Investigations of Dielectric Low Temperature Properties of Amorphous Solids — •Benedikt Frey, Marcel Haas, Marius Lutz, Diana Körner, Andreas Fleischmann, Andreas Reiser, and Christian Enss — Kirchhoff-Institute for Physics , Heidelberg University, D-69120 Heidelberg

The low temperature properties of amorphous solids are governed by atomic tunneling systems, which can be described as two-level systems (TLS) with a distribution of their energy splitting E, as assumed by the phenomenological standard tunneling model. Recent interest in these systems due to their deteriorative effects on the performance of superconducting quantum devices have been leading to novel experimental investigations of atomic tunneling systems also driven by novel measurement techniques.

We use microfabricated superconducting resonators in a bridge-type setup to study the dielectric rf-response of the amorphous sample in the presence of an electric bias field. The bias field modifies the energy splitting E of a TLS and allows to probe different regions of the TLS distribution. This technique enables various opportunities for studying TLS more in-depth. We see a correlation between the dielectric loss and the bias field sweep rate, which can be well described within a theory based on Landau-Zener transitions. Moreover, a desaturation of the TLS occupation number also occurs, when noise is used as the bias signal. These results are compared to detailed numerical simulations, showing in general a good agreement.