Extended Data Fig. 4: Uncorrected single phonon phase gate data.

a, b, Data from Fig. 2c,d plotted here in log scale, without a visibility correction. The average visibility for the Mach-Zehnder interferometry (not to be confused with the measurement visibility matrix) is \({{\mathcal{V}}}_{{\rm{MZ,raw}}}\equiv ({P}_{\max }-{P}_{\min })/({P}_{\max }+{P}_{\min })\)\(=0.979\pm 0.006\). We also measured the excited state population for each qubit after releasing a single phonon and being cooled by the acoustic channel, shown by the corresponding colored dashed lines, with the color-shaded regions representing one standard deviation in uncertainty. The noise floor limits the maximum measurable visibility to \(({P}_{\max }-{P}_{{\rm{floor}}})/({P}_{\max }+{P}_{{\rm{floor}}})=0.986\pm 0.001\).