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TT: Fachverband Tiefe Temperaturen
TT 8: Measurement Technology and Cryogenics
TT 8.3: Vortrag
Montag, 17. März 2025, 15:30–15:45, H32
The noise-o-meter: A novel device to disentangle noise sources in superconducting devices — •Lukas Münch, Daniel Hengstler, Matthew Herbst, David Mazibrada, Andreas Reifenberger, Markus Renger, Christian Ständer, Rui Yang, Andreas Fleischmann, Loredana Gastaldo, and Christian Enss — Kirchhoff-Institute for Physics, Heidelberg University
In many applications of superconducting devices, different intrinsic noise sources are limiting the ultimate performance of the device. Our new device allows to conveniently disentangle the noise of the read-out chain, and to distinguish between magnetic flux noise and other noise sources. It consists of a microfabricated Wheatstone-like bridge of four superconducting inductors, two of which are filled with a sample material, which is read out via a pair of two-stage dc-SQUID read-out chains. The device can be operated in two modes. In the passive mode, the output signals of both read-out chains are cross-correlated, which allows the measurement of the total noise of all intrinsic noise sources within a sample material. In the active mode, the bridge is driven by an AC current to measure the samples complex susceptibility and, therefore, specifically the samples magnetic noise via the fluctuation-dissipation theorem. We used this setup to characterize SiO2, Ag:Er and Au:Er films in a large temperature range from 20 to 800 mK. We discuss our design considerations and present the results of these measurements. Furthermore, we address the current performance limits of SΦ = 30 nΦ0/√Hz in passive mode and around 10 ppm for the concentration of magnetic impurities in active mode.