SQUID-based high-resolution thermometer Original Research Article

High-resolution thermometers (HRTs) based on the detection of magnetization changes of a magnetic material using very sensitive superconducting quantum interference device (SQUID) have routinely achieved temperature resolution of 0.1 nK/Hz at temperatures below 4 K in several laboratories. The resolution of these thermometers has reached the fundamental limit imposed by thermodynamic fluctuations. The principle of operation as well as the theory of the noise are presented. Some recent discoveries using HRT are discussed.