Current Sensing Noise Thermometry: A Fast Practical Solution to Low Temperature Measurement
We describe the design and performance of a series of fast, precise current sensing noise thermometers. The thermometers have been fabricated with a range of resistances from 1.290 \(\Omega \) down to 0.2 m\(\Omega \). This results in either a thermometer that has been optimised for speed, taking advantage of the improvements in superconducting quantum interference device noise and bandwidth, or a thermometer optimised for ultra-low temperature measurement, minimising the system noise temperature. With a single temperature calibration point, we show that noise thermometers can be used for accurate measurements over a wide range of temperatures below 4 K. Comparisons with a melting curve thermometer, a calibrated germanium thermometer and a pulsed platinum nuclear magnetic resonance thermometer are presented. For the 1.290 \(\Omega \) resistance we measure a 1 % precision in just 100 ms, and have shown this to be independent of temperature.
KeywordsJohnson noise Fixed point device Precision SQUID
This work was supported by the European Metrology Research Program (EMRP). The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. Additional support was through the MICROKELVIN project. We acknowledge the support of the European Community - Research Infrastructures under the FP7 Capacities Specific Programme, MICROKELVIN project number 228464.
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