SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 58: Poster: Superconductivity II

TT 58.4: Poster

Donnerstag, 30. März 2023, 15:00–18:00, P2/OG3

Identification of noise sources in superconducting microstructures — •R. Yang, A. Fleischmann, D. Hengstler, M. Herbst, D. Mazibrada, L. Münch, A. Reifenberger, C. Ständer, and C. Enss — Kirchhoff-Institute for Physics, Heidelberg University, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany.

Improving the performance of a superconducting device often means identifying and eliminating noise. Many potential noise sources are independent of the specific experimental set-up and transferable across many device categories such as qubits, SQUIDs, and superconducting detectors. We have constructed a stand-alone device able to representably probe specific noise sources. The set-up consists of a Wheatstone-like bridge of microfabricated superconducting inductors and a pair of two-stage dc-SQUID read-out chains. Cross-correlation removes noise contributions from the read-out electronics giving us the sum total of all noise in the superconducting circuit. If, in comparison, the Wheatstone bridge is AC-driven, we can measure a sample material’s magnetic noise via the material’s complex AC susceptibility using the fluctuation-dissipation theorem. The experiment is performed at temperatures between T = 10 mK and 1000 mK in the frequency range from f = 100 mHz to 100 kHz on an experimental holder with excellent thermal coupling and shielding. We present first results of measurements on SiO₂ and Ag:Er thin films and compare these results with previous measurements on Au:Er. In addition, we demonstrate our device’s ability to probe the dynamics of magnetic moments in a sample material.