Absolute power measurement with transition edge sensors and SQUID amplifier

Abstract

We have developed a new cryogenic radiometer for determining absolute power. This instrument is composed of a superconducting transition edge sensor as a thermometer, a silicon substrate as a heat absorber, and a SQUID amplifier as a readout. The input power is measured with electrical substitution of a heater on the device. By using very sharp transition of the thermometer, the device temperature is locked within its transition temperature. This device demonstrated very wide dynamic range of more than 105, very low noise equivalent power of 1.5 nW. These properties are very attractive to be used as highly precise power measurement instruments in metrological fields. © 2006 IOP Publishing Ltd.