Fig. 5
From: Tuning high-Q nonlinear dynamics in a disordered quantum magnet
Evolution of resonant behavior vs. pump amplitude at T = 0.11 K and Ht = 0 for a 202 Hz pump. a Fano parameter q vs. drive amplitude showing a continuous evolution including a smooth crossing through zero. Dashed line is a guide to the eye. b Evolution of the phase of the complex susceptibility at f = fpump for the nonlinear (open symbols) and linear (filled symbols) responses. The zero crossings of q are associated with a local minimum in the dissipation and a corresponding minimum in the phase shift of the linear probe response as the probe frequency approaches the pump frequency. \(\phi \left( q \right) = \tan ^{ - 1}\frac{{q^2}}{{1 - q^2}}\) (blue dotted curve) follows from Eq. 2 in the text, whereas the solid blue curve (see Eq. 3 and associated discussion in text) provides a better description of the experimental data. c Real susceptibility χ’ measured directly at f = fpump (open symbols) and determined by extrapolating the fitted Fano resonance to f = fpump (filled symbols), showing the contrast in behavior between the nonlinear and linear responses, respectively. d Fano linewidth Γ vs. ac drive hpump. Increasing the drive amplitude broadens the linewidth and hence reduces the oscillator Q. All error bars are SDs
