Using first-principles calculations and magnetic resonance experiments, we investigated the physical properties of the negatively charged nitrogen-vacancy (NV) center in 4H-SiC, a promising spin qubit. Our predictive theoretical model in conjunction with experimental measurements reveals a large sensitivity to strain and symmetry. The measured and computed zero-phonon lines (ZPLs) are in agreement and show a consistent trend as a function of the defect location in the crystal. The computed ZPLs are extremely sensitive to the geometrical configurations of the ground and excited states, and large supercells with more than 2 000 atoms are required to obtain accurate numerical results. We find that the computed decoherence time of the basal NV centers at zero magnetic field is substantially larger than that of the axial configurations. Furthermore, at natural nuclear spin abundance and zero field, the Hahn-echo coherence time of one of the basal configurations is similar to that of the axial divacancy in isotopically purified SiC.

中文翻译：

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4H-SiC中氮空位中心的理论与实验研究

使用第一性原理计算和磁共振实验，我们研究了 4H-SiC 中带负电荷的氮空位 (NV) 中心的物理性质，4H-SiC 是一种很有前途的自旋量子位。我们的预测理论模型与实验测量相结合，揭示了对应变和对称性的很大敏感性。测量和计算的零声子线 (ZPL) 是一致的，并显示出作为晶体中缺陷位置函数的一致趋势。计算出的 ZPL 对基态和激发态的几何构型极为敏感，需要具有超过 2 000 个原子的大型超胞才能获得准确的数值结果。我们发现在零磁场下计算的基础 NV 中心的退相干时间大大大于轴向配置的退相干时间。此外，