Berlin 2024 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 18: Superconductivity: Poster

TT 18.58: Poster

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

Noise Thermometers for mK- and µ K-Temperatures — •Leo Knapp, Pascal Willer, Christian Ständer, Nathalie Probst, Andreas Reiser, Andreas Fleischmann, and Christian Enss — Kirchhoff-Institute for Physics, Heidelberg University, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany.

To measure mK-temperatures is a big challenge in solid state physics labs. We developed a prototype of a cross-correlated, current sensing noise thermometer for mK-temperatures. The basic concept relies on the thermal motion of charge carriers in a bulk metal resistor. Two DC-SQUIDs detect the corresponding noise signal which is then recorded via two identical but independent amplifier chains. The method of cross correlation is used to eliminate uncorrelated noise contributions from the amplifier chains. As resistor material we use the alloy Ag₆₀Cu₄₀. We show that this approach towards a relative primary thermometer is able to cover the complete temperature range below 4 K. We discuss the design, the considerations that lead to it and present first experimental results down to mK temperatures.