Fig. 5. Initial state preparation.

(A and B) The pulsed optically detected magnetic resonance (ODMR) spectrum of laser initialized state ρ₀ and the state after applying the CNOT operation. (C) The decay of ¹⁴N nuclear spin’s coherence under the green laser illumination. The pulse sequence is shown in the inset, including the preparation of the coherent state $({\mid 0\rangle }_{\mathrm{N}}+{\mid 1\rangle }_{\mathrm{N}})/\sqrt{2}$, the laser-induced dephasing, and the map to the electron spin for optical readout. (D) The repolarization of ¹⁴N nuclear spin from the state ∣1〉_N to the state ∣0〉_N under laser illumination.