Regensburg 2022 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 31: Superconducting Electronics and Cryogenics: Poster Session

TT 31.16: Poster

Thursday, September 8, 2022, 15:00–18:00, P1

The Influence of Continuous Electric Bias Fields on the Dielectric Loss of Atomic Tunneling Systems — •Jan Blickberndt, Christian Ständer, Lukas Münch, Marcel Haas, Andreas Reiser, Andreas Fleischmann, and Christian Enss — Kirchhoff-Institute for Physics, Heidelberg, Germany

The low temperature properties of amorphous solids are mainly determined by atomic tunneling systems (TSs), which are known to act as a major source of noise and decoherence in superconducting quantum devices. We investigate the non-equilibrium dielectric loss of atomic tunneling systems under the influence of continuous electric bias fields at very low temperatures. By measuring the quality factor of a micro-fabricated superconducting resonator, the dielectric loss of the sample is obtained. Simultaneously, an electric bias field can be applied via a cover electrode, which allows us to sweep TSs through resonance by modulating their energy splitting. Experimentally, we found that for slow changing bias fields, TSs are saturated by the driving field leading to a constant loss. For faster bias rates, more and more TSs are swept through resonance and therefore contribute to an increasing loss. In the limit of fast continuous bias sweeps relaxation in between consecutive crossings diminishes and multiple coherent Landau-Zener transitions are possible, reducing the loss back to the saturation limit. We are able to verify these experimental results with a Monte Carlo based numerical simulation that shows good qualitative agreement.