AI 中文总结
本研究通过电子自旋退相干的从头算计算，利用7种碳缺陷的自旋相干指纹，建立了与光学光谱互补的六方氮化硼碳基自旋量子比特结构识别方法。
AI 中文摘要
六方氮化硼中的碳相关缺陷是有前景的室温单自旋量子比特和量子传感器，但其原子结构在很大程度上仍未被识别。本文通过电子自旋退相干的从头算计算表明，每个缺陷的原子结构都印记在其自旋相干性中。我们绘制了7种候选碳缺陷在磁场和4种同位素工程化核自旋浴下的Hahn回波动力学，发现电子自旋回波包络调制在缺陷特有的磁场下出现，此时最近邻核自旋满足由其超精细和四极耦合设定的抵消条件。这些磁场和调制频率仅通过计算得到的超精细和四极张量即可从分析模型中得出，且在同位素取代后会发生偏移或消失。在低磁场下，相干时间的磁场依赖性根据碳占据的子晶格将缺陷分为两类。这些退相干指纹可在同位素工程化样品中直接测试，建立了一种与光学光谱互补的结构识别途径。
英文摘要
Carbon-related defects in hexagonal boron nitride are promising room-temperature single-spin qubits and quantum sensors, but their atomic structures remain largely unidentified. Here we show, using first-principles calculations of electron-spin decoherence, that the atomic structure of each defect is imprinted in its spin coherence. Mapping the Hahn-echo dynamics of seven candidate carbon defects across magnetic field and four isotope-engineered nuclear-spin baths, we find that electron-spin-echo envelope modulation emerges at defect-specific magnetic fields, at which the nearest-neighbor nuclear spins satisfy a cancellation condition set by their hyperfine and quadrupole couplings. Both the fields and the modulation frequencies follow from an analytical model using computed hyperfine and quadrupole tensors alone, and they shift or vanish upon isotope substitution. At low fields, the field dependence of the coherence time separates the defects into two classes according to the sublattice occupied by carbon. These decoherence fingerprints, directly testable in isotope-engineered samples, establish a structural identification route complementary to optical spectroscopy.
Comments23 pages, 7 figures; includes Supplementary Information (20 pages, 13 figures, 14 tables)
