Figure 5. Observation of the fundamental resonance.

Experimentally observed electron temperatures of the QCR and of the probe resistor as functions of the frequency and power of the external microwave drive. The measurement scheme is illustrated in Fig. 1a. We also show a trace of the refrigerator temperature at −54-dBm room temperature power (markers) together with a Lorentzian fit (solid line). The indicated room temperature power levels decrease according to Supplementary Fig. 1c before reaching the sample.