Extended Data Fig. 3: π-pulse visibility.
From: Ideal refocusing of an optically active spin qubit under strong hyperfine interactions
a, Visibility measurement on a 40s timescale with Nπ = 162. The left panel displays the readout signal for \(\left\vert \uparrow \right\rangle\) -state initialization. The integrated counts under the yellow dark-shaded area are background-subtracted with the counts in the yellow light-shaded area, yielding cts↑ = 1753. The right panel displays the readout signal following the same pulse sequence with an additional π-pulse (\(\left\vert \downarrow \right\rangle\)-state initialization) yielding cts↓ = 917. This corresponds to a π-pulse visibility of \({{{\mathcal{F}}}}=99.30(5) \%\) (Methods). b, Visibility on long timescales. Data points display the fitted maximal visibility, \({v}_{\max }\), in long CPMG measurements as a function of the number of π-pulses in the sequence, Nπ. The black curve illustrates that a π-pulse visibility \(\bar{{{{\mathcal{F}}}}}=97.81(5) \%\) is typically achieved over longer integration times (Methods). The error bars represent the standard deviation errors on fit parameter \({v}_{\max }\).
