论文标题
在理想和无序的Si量子点中对山谷分裂的电磁控制
Electromagnetic control of valley splitting in ideal and disordered Si quantum dots
论文作者
论文摘要
在硅自旋量子箱中，必须将山谷分裂远离量子式Zeeman分裂，以防止快速量子放松。在这项工作中，我们详细研究了山谷分裂如何取决于电场和磁场以及理想和无序SI/SIGE接口的量子点几何形状。从理论上讲，我们对逼真的静电定义的量子点进行建模，并为空地外电子运动找到精确的地面和激发态。这使我们能够找到电子信封功能及其对电场和磁场的依赖性。对于具有理想界面的量子点，由平面磁场驱动的电子的轻微回旋运动稍微增加了山谷的分裂。重要的是，我们的建模使得可以分析接口障碍的任意配置的效果。与以前的研究一致，我们表明界面步骤可以显着减少山谷的分裂。有趣的是，根据界面步骤的位置，磁场可以增加或进一步抑制山谷分裂。此外，山谷分裂可以线性地扩展，或者在接口步骤的存在下，与电场非线性。
In silicon spin qubits, the valley splitting must be tuned far away from the qubit Zeeman splitting to prevent fast qubit relaxation. In this work, we study in detail how the valley splitting depends on the electric and magnetic fields as well as the quantum dot geometry for both ideal and disordered Si/SiGe interfaces. We theoretically model a realistic electrostatically defined quantum dot and find the exact ground and excited states for the out-of-plane electron motion. This enables us to find the electron envelope function and its dependence on the electric and magnetic fields. For a quantum dot with an ideal interface, the slight cyclotron motion of electrons driven by an in-plane magnetic field slightly increases the valley splitting. Importantly, our modeling makes it possible to analyze the effect of arbitrary configurations of interface disorders. In agreement with previous studies, we show that interface steps can significantly reduce the valley splitting. Interestingly, depending on where the interface steps are located, the magnetic field can increase or further suppress the valley splitting. Moreover, the valley splitting can scale linearly or, in the presence of interface steps, non-linearly with the electric field.
