Fig. 2: Coherence measurements and quantum control of the SnV.

a Lifetime measurement of the SnV. By applying the narrowband pulse at π-rotation power and analyzing the fluorescence response, we extract an average spontaneous emission lifetime of 16.2 (6) ns, which corresponds to the T₁ of our optical qubit. b Time-resolved Rabi oscillations under a quasi-continuous excitation scheme, where a continuous wave laser is switched on with an acousto-optic modulator, and the fluorescence response is recorded. The observed Rabi oscillations establish the coherence of the investigated qubit. From the amplitude decay of the oscillations, we estimate an overall dephasing of the optical qubit under the experimental conditions as \({T}_{2}^{*}\) = 10.9 (4) ns. c Optical Rabi rotations extracted by varying the power and integrating the total amount of registered photons using a ~40 GHz wide pulse of 15 ps duration. The dashed line indicates a π-rotation. d Photon purity measurement of the emitter fluorescence at a power calibrated from (c, dashed line) to perform a π-rotation. The estimated g⁽²⁾(0) is 0.1 (1), which confirms the single-photon nature of the collected emission. e Optical Rabi rotations extracted by varying the pulse power and integrating the total amount of registered photons using a 1400 GHz wide quadrilateral broadband pulse with femtosecond duration. The dashed line indicates a π-rotation. The peak around 4 \(\sqrt{{{{\rm{pJ}}}}}\) corresponds to the 3π rotation. Inset: Measurement of the pulse duration using an autocorrelator. Full-width-half-maximum of the sech² autocorrelation signal is multiplied by a factor of 0.647 to deconvolve the pulse duration. f Photon purity measurement of the emitter fluorescence at a power calibrated from (e, dashed line) to perform a π-rotation. With the estimated g⁽²⁾(0) = 0.2 (6), the single-photon emission is confirmed but a higher background contribution compared to narrowband pulses is detected. Horizontal error bars in c and d correspond to the error specified by the powermeter sensor head. The remaining uncertainties in the figure are extracted from the 95% confidence intervals returned by the fit algorithms.