Fig. 2: Resonant frequency loops and their dependence on V_G range.

a Frequency response of the mode whose resonant frequency is shown in Fig. 1d as a function of \({f}_{{{{{{\rm{d}}}}}}}\) and \({V}_{{{{{{\rm{G}}}}}}}\). The response is extracted from the spectrum of current \(I\) which peaks at the resonant frequency. In stage 1, \({V}_{{{{{{\rm{G}}}}}}}\) is stepped from \(20\) V up to ≈\(30\) V. In stage 2, \({V}_{{{{{{\rm{G}}}}}}}\) is stepped from ≈\(30\) V down to \(25\) V. In stage 3, \({V}_{{{{{{\rm{G}}}}}}}\) is stepped from \(25\) V up to ≈\(30\) V again. Stages 1–3 are done sequentially and in one go. The left panel shows the superimposed spectra from stages 1–3. b Frequency response measured upon increasing and decreasing \({V}_{{{{{{\rm{G}}}}}}}\) over various \({V}_{{{{{{\rm{G}}}}}}}\) ranges. The panels are made by superimposing data measured with increasing \({V}_{{{{{{\rm{G}}}}}}}\) and data measured with decreasing \({V}_{{{{{{\rm{G}}}}}}}\). c Superimposed dependences of the resonant frequency \(f\) on \({V}_{{{{{{\rm{G}}}}}}}\) extracted from the four panels in b.