Berlin 2024 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 18: Superconductivity: Poster

TT 18.52: Poster

Monday, March 18, 2024, 15:00–18:00, Poster C

Identification of Noise Sources in Superconducting Microstructures — •M. Renger, D. Hengstler, M. Herbst, F. Kaiser, D. Mazibrada, L. Münch, A. Reifenberger, C. Ständer, R. Yang, A. Fleischmann, L. Gastaldo, 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 new measurements of SiO₂ and Ag:Er thin films and an macroscopic sample of YbRh₂Si₂, conducted with new versions of our device with increased symmetry and coupling.