A non-invasive electron thermometer based on charge sensing of a quantum dot

We present a thermometry scheme to extract the temperature of a two-dimensional electron gas by monitoring the charge occupation of a weakly tunnel-coupled thermometer quantum dot using a quantum point contact detector. Electronic temperatures between 120 and 951 mK are measured with an accuracy of better than 1 mK in the best case, and agree with the lattice temperature measured by a resistance thermometer. The thermometer is non-invasive and does not pass a current through the electron system being measured. The tuning is independent of temperature, and the device is robust in a magnetic field up to 5.6T. (C) 2013 AIP Publishing LLC.