Fig. 5
An interleaved series of 1000 T1 relaxation and \(T_2^ \ast\) Ramsey measurements of qubit A. a Qubit frequency (f01) shift relative to its mean (\(\overline {f_{01}}\)) determined from the Ramsey experiments. b Extracted T1 (black), \(T_2^ \ast\) (blue), and \(T_\phi\) (red). c Histogram of \(T_2^ \ast\) from the data in b. d Histogram of the data in a. The frequency fluctuations from a are analysed by overlapping Allan deviation (e) and by Welch-method spectrum (f). The solid and dashed lines represent the modelled noise, where the noise amplitudes are the same for both types of analysis. g Histogram of \(T_\phi\) from the data in b. The solid line indicates the \(T_\phi\) limit calculated by integrating the frequency noise from e. h Histogram of \(T_2^ \ast {\mathrm{/}}T_1\) from the data in b. We find \(1.4 < T_2^ \ast /T_1 < 2.2\) in 81.7% of the counts. This data was taken during cooldown 3
