Fig. 2: DC voltage-tunable Josephson emission.
From: DC-operated Josephson junction arrays as a cryogenic on-chip microwave measurement platform
a Power spectral density S as a function of frequency ν and junction voltage Vj, with Vj converted to units of Hz using the Josephson equation. Data is for MoGe-bot at 300 mK and frustration \(\tilde{f}=1\). The maximum value of the colorbar is set to 0.5 ⋅ 10−8 fW Hz−1 to increase the visibility of the graph. The dashed lines respresent the expected Josephson frequency νj and its harmonic 2νj. b Selected spectra of the radiation map in panel a (solid symbols) and fits (solid lines). Vertical dashed lines indicate the expected Josephson frequency. c Integrated power Pν over bias voltage for MoGe-bot (d top) as a function of frequency ν at frustrations of 0 (red) and 1 (blue). e The power integrated over voltage (red) and the measured white noise power spectral density (cyan) at frustration \(\tilde{f}=0\), both normalized to their maximum value for MoGe-bot (f top). The white noise is an average of 25 measurements with a biasing current of 6.0–6.5 mA at a frustration of \(\tilde{f}=0\).
