Radio-Frequency Coulomb-Blockade Thermometry

We present a scheme and demonstrate measurements of a Coulomb-blockade thermometer (CBT) in a microwave-transmission setup. The sensor is embedded in an LCR resonator, where R is determined by the conductance of the junction array of the CBT. A transmission measurement yields a signal that is directly proportional to the conductance of the CBT, thus enabling the calibration-free operation of the thermome-ter. This is verified by measuring an identical sensor simultaneously in the usual dc setup. The important advantage of the rf measurement is its speed: the whole bias dependence of the CBT conductance can now be measured in a time of about 100 ms, which is 1000 times faster than in a standard dc measurement. The achieved noise-equivalent temperature of this rf primary measurement is about 1 mK/root Hz at the bath temperature T = 200 mK.

Automated summary

This study introduces a new scheme for a Coulomb-blockade thermometer (CBT) and demonstrates measurements in a microwave-transmission setup. The signal obtained from a transmission measurement is directly proportional to the conductance of the CBT, enabling calibration-free operation. The rf measurement offers a significant speed advantage, allowing for faster measurements compared to standard dc setups.