Fig. 3: Minimum number of measurements Nmeas needed to resolve the quench phase shift with a unit signal-to-noise ratio in a Hahn-echo protocol of time tf: \({N}_{{{{{{{{\rm{meas}}}}}}}}}({t}_{f})\equiv {\left|\langle {\hat{\sigma }}_{y}({t}_{f})\rangle \right|}^{-2}\).
From: Intrinsic and induced quantum quenches for enhancing qubit-based quantum noise spectroscopy

Because of bath-induced dephasing, it will in general take many repeated measurements to resolve the quench phase shift (QPS). We use the same Gaussian baths (and labeling) as in Fig. 2. Panel (a) corresponds to a dimensionless coupling parameter α = 0.1, while (b) corresponds to α = 0.01. All plots correspond to a temperature kBT = 0.01ωc.