Figure 3: Microwave drive and temperature dependence of 1/f noise in superconducting microresonators.
From: Evidence for interacting two-level systems from the 1/f noise of a superconducting resonator
(a) Fractional frequency spectra at three different temperatures for resonator Res2. For frequencies below 10 Hz the slope is −0.97 with a goodness-of-fit parameter R2=0.9, white noise dominates from 50 Hz. (b) 1/f noise level versus average number of photons within the resonator Res2 at several different temperatures. The average photon number is calculated as ‹n›=Wsto/ħ, where ħ is Planck’s constant, ω0 is the resonators centre frequency and 
, where Papp is the applied microwave drive and Smin21 is the magnitude of the resonance dip. The data are fit to the noise spectra calculated from the model. Inset: 1/f noise versus average number of photons for resonator Res1 showing the leveling off at high photon numbers (high microwave drive) that is because of flicker noise floor of the amplifier chain. The error bars indicate type A uncertainties from the propagated error of the fitting process.
