标题： 二维六方氮化硼中硼空位/碳缺陷的自旋量子比特特性 显示英文标题

标题： Spin Qubit Properties of the Boron-Vacancy/Carbon Defect in the Two-Dimensional Hexagonal Boron Nitride

摘要： 二维材料中的自旋量子比特缺陷相对于三维材料中的缺陷具有许多优势，包括缺陷创建和控制的更简单技术以及量子比特的可访问性。 在本工作中，我们选择六方氮化硼（hBN）中的VBCB缺陷作为可能的光学可控自旋量子比特，并解释其三重态基态和电中性。 在该缺陷中，一个硼空位与一个碳掺杂原子结合，该碳掺杂原子取代了最接近空位的硼原子。 我们的密度泛函理论计算证实，该系统具有动态稳定的自旋三重态和单态基态。 根据我们的线性响应GW计算，自旋敏感的电子态局域在三个配位不足的N原子周围，并在带隙内的电子态密度中形成局部峰。 利用从求解Bethe-Salpeter方程得到的三重态和单态基态能量以及光学激发态的能量，我们构建了自旋极化循环，发现该循环有利于自旋量子比特的初始化。 计算得到的零场分裂参数确保了三重态基态中自旋投影之间的分裂能量与已知的自旋量子比特相当。 因此，我们提出hBN中的VBCB缺陷作为一种有前途的自旋量子比特。 显示英文摘要

摘要： Spin qubit defects in two-dimensional materials have a number of advantages over those in three-dimensional hosts including simpler technologies for the defect creation and control, as well as qubit accessibility. In this work, we select the VBCB defect in the hexagonal boron nitride (hBN) as a possible optically controllable spin qubit and explain its triplet ground state and neutrality. In this defect a boron vacancy is combined with a carbon dopant substituting the closest boron atom to the vacancy. Our density-functional-theory calculations confirmed that the system has dynamically stable spin triplet and singlet ground states. As revealed from our linear response GW calculations, the spin-sensitive electronic states are localized around the three undercoordinated N atoms and make local peaks in the density of electronic states within the bandgap. Using the triplet and singlet ground state energies, as well as the energies of the optically excited states, obtained from solution to the Bethe-Salpeter equation, we construct the spin-polarization cycle, which is found to be favorable for the spin qubit initialization. The calculated zero-field splitting parameters ensure that the splitting energy between the spin projections in the triplet ground state is comparable to that of the known spin qubits. We thus propose the VBCB defect in hBN as a promising spin qubit.