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TT: Fachverband Tiefe Temperaturen

TT 59: Transport: Poster

TT 59.15: Poster

Mittwoch, 20. März 2024, 15:00–18:00, Poster E

Dynamic Control of Dielectric Loss in a Bulk Glass by Manipulation of Atomic Tunneling Systems via Electric Bias Fields — •Jan Blickberndt, Christian Ständer, Lukas Münch, Marcel Haas, Andreas Reiser, Andreas Fleischmann, and Christian Enss — Kirchhoff-Institute for Physics, Heidelberg, Germany

Atomic tunneling systems (TSs) are inherent to disordered structures and strongly determine the low temperature dielectric properties of amorphous solids. However, they also manifest as parasitic surface defects in superconducting quantum devices, contributing significantly to noise and decoherence. Here we investigate the non-equilibrium dielectric loss of atomic tunneling systems in a bulk glass sample by measuring the quality factor of a superconducting microstructured LC-resonator. Our approach involves the application of an electric bias field via a cover electrode, which allows us to modulate the TSs energy splitting, inducing Landau-Zener transitions experimentally observed as an alteration of the resonator loss. We are able to control the loss by varying the bias rate via the amplitude or frequency of the bias signal. Our results indicate a constant loss for slow bias rates due to TS saturation. Increasing the bias rate disrupts the TS saturation and leads to an increased loss. In the limit of fast continuous bias sweeps, the bias frequency exceeds the TS relaxation rate, and interference of multiple coherent Landau-Zener transitions is possible, resulting in a decreasing dielectric loss and ultimately a return to the saturation limit. We are able to confirm our experimental findings with a Monte-Carlo based numerical simulation of the tunneling dynamics.

Keywords: amorphous dielectrics; tunneling systems; microwave resonators; Landau-Zener dynamics; dielectric loss