标题： 氧化镁中的NV-中心作为混合量子技术的自旋量子位 显示英文标题

标题： An NV- center in magnesium oxide as a spin qubit for hybrid quantum technologies

摘要： 近期预测表明，氧化物（如 MgO 和 CaO）可能作为具有较长相干时间的自旋缺陷的宿主，因此有望成为量子应用的有前景材料。然而，在大多数情况下，特定的缺陷尚未被识别。 在此，通过使用高通量的第一性原理框架和先进的电子结构方法，我们确定了 MgO 中一种由氮间隙和镁空位组成的负电荷复合缺陷，该复合缺陷具有良好的电子和光学性质，适用于混合量子技术。 我们展示了这种 NV- 中心具有稳定的三重态基态和激发态，并且单重态存储态能够实现光学初始化和自旋依赖读出。 我们预测了几种特性，包括吸收、发射和零声子线能量以及零场分裂张量和超精细相互作用参数，这些都可以帮助实验中对该缺陷的识别。 我们的计算显示，由于强烈的准 Jahn-Teller 效应和低频声子模式，MgO 中的 NV- 中心受到显著的振动耦合影响。 我们讨论了减少这种耦合并增加德拜-沃勒因子的设计策略，包括应变效应和缺陷态的局域化。 我们提出，NV- 缺陷的良好性质与 MgO 的技术成熟度相结合，可能使混合经典-量子应用成为可能，例如自旋电子量子传感器和单量子比特门。 显示英文摘要

摘要： Recent predictions suggest that oxides, such as MgO and CaO, could serve as hosts of spin defects with long coherence times and thus be promising materials for quantum applications. However, in most cases specific defects have not yet been identified. Here, by using a high-throughput first-principles framework and advanced electronic structure methods, we identify a negatively-charged complex between a nitrogen interstitial and a magnesium vacancy in MgO with favorable electronic and optical properties for hybrid quantum technologies. We show that this NV- center has stable triplet ground and excited states, with singlet shelving states enabling optical initialization and spin-dependent readout. We predict several properties, including absorption, emission, and zero-phonon line energies, as well as zero-field splitting tensor, and hyperfine interaction parameters, which can aid in the experimental identification of this defect. Our calculations show that due to a strong pseudo-Jahn Teller effect and low frequency phonon modes, the NV- center in MgO is subject to a substantial vibronic coupling. We discuss design strategies to reduce such coupling and increase the Debye-Waller factor, including the effect of strain and the localization of the defect states. We propose that the favorable properties of the NV- defect, along with the technological maturity of MgO, could enable hybrid classical-quantum applications, such as spintronic quantum sensors and single qubit gates.