Fig. 4: Single-shot readout of the nuclear spin state.

a Readout fidelity of the ¹⁴N nuclear spin as a function of the measurement repetition number. The data points with θ = 7° ± 2°, τ = 374 ns are shown in red squares, while the data points with θ = 7° ± 2°, τ = 370 ns are shown in blue circles. b ¹⁴N nuclear spin relaxation time (bright state in orange and dark state in blue) as a function of the duty cycle of the excitation laser pulses. The inset illustrates the experimental pulse sequence. The duty cycle is defined as the ratio of the measurement time to the waiting time in the sequence. In (a) and (b), the vertical error bars display the statistical error (s.d.) from the fit. c ¹⁴N nuclear spin NMR, obtained by varying the radio-frequency (RF) pulse frequency at a fixed pulse duration of 30 μs. d ¹⁴N nuclear spin Rabi oscillations. A resonant RF pulse of a specific length is applied between every two sequential RIMs to flip the nuclear spin between the \({| 0\left.\right\rangle }_{n}\) and \({|+1\left.\right\rangle }_{n}\) states, while the electron is at the \({| 0\left.\right\rangle }_{n}\) state.