Fig. 4: Measurements of cavity resonances by photon-assisted tunneling steps of the SPD.
From: Detection of single-mode thermal microwave photons using an underdamped Josephson junction
a IV curves at various incident radiation powers and constant frequency of 13.9537 GHz; b Calibration curve to translate the position of current step to dB; c IV curves at various frequencies of incoming radiation and constant power; d,e Comparison of frequency response of the cavity measured at room temperature by VNA (blue) and at 17 mK measured by photon-assisted tunneling steps in SPD (red). d Resonance at 8.8 GHz, e resonance at 13.9 GHz. Both dependences are normalized to the same level so that their maxima are at 0 dB. Blue curves are actually the enlarged curves from Fig. 2b.
