Davidsson Joel, Onizhuk Mykyta, Vorwerk Christian, Galli Giulia
Department of Physics, Chemistry and Biology, Linköping University, SE-581 83, Linköping, Sweden.
Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL, 60637, USA.
Nat Commun. 2024 Jun 6;15(1):4812. doi: 10.1038/s41467-024-49057-8.
Virtually noiseless due to the scarcity of spinful nuclei in the lattice, simple oxides hold promise as hosts of solid-state spin qubits. However, no suitable spin defect has yet been found in these systems. Using high-throughput first-principles calculations, we predict spin defects in calcium oxide with electronic properties remarkably similar to those of the NV center in diamond. These defects are charged complexes where a dopant atom - Sb, Bi, or I - occupies the volume vacated by adjacent cation and anion vacancies. The predicted zero phonon line shows that the Bi complex emits in the telecommunication range, and the computed many-body energy levels suggest a viable optical cycle required for qubit initialization. Notably, the high-spin nucleus of each dopant strongly couples to the electron spin, leading to many controllable quantum levels and the emergence of atomic clock-like transitions that are well protected from environmental noise. Specifically, the Hanh-echo coherence time increases beyond seconds at the clock-like transition in the defect with Bi. Our results pave the way to designing quantum states with long coherence times in simple oxides, making them attractive platforms for quantum technologies.
由于晶格中自旋核的稀缺，简单氧化物几乎没有噪声，有望成为固态自旋量子比特的宿主。然而，在这些系统中尚未发现合适的自旋缺陷。利用高通量第一性原理计算，我们预测氧化钙中的自旋缺陷具有与金刚石中的NV中心显著相似的电子性质。这些缺陷是带电复合体，其中掺杂原子（Sb、Bi或I）占据相邻阳离子和阴离子空位腾出的体积。预测的零声子线表明，Bi复合体在电信范围内发射，计算出的多体能级表明了量子比特初始化所需的可行光学循环。值得注意的是，每个掺杂剂的高自旋核与电子自旋强烈耦合，导致许多可控量子能级以及出现像原子钟一样的跃迁，这些跃迁能很好地抵御环境噪声。具体而言，在含有Bi的缺陷中，类似原子钟跃迁处的 Hahn 回波相干时间增加到数秒以上。我们的结果为在简单氧化物中设计具有长相干时间的量子态铺平了道路，使其成为量子技术有吸引力的平台。
