The valley splitting (VS) of a silicon quantum dot plays an important role for the performance and scalability of silicon spin qubits. In this paper we investigate the VS of a SiGe/Si/SiGe heterostructure as a function of the size and location of the silicon quantum dot. We use the effective mass approach to describe a realistic system, which takes into account concentration fluctuations at the Si/SiGe interfaces and also the interface roughness. We predict that the size of the quantum dot is an important parameter for the enhancement of the VS and it can also induce a transition between the disorder-dominated to deterministic-enhanced regimes. Analyzing how the VS changes when we move the quantum dot in a specific direction, we obtain that the size of the quantum dot can be used to reduce the variability of the VS, which is relevant for charge/spin shuttling.

中文翻译：

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谷分裂取决于硅量子点的大小和位置

硅量子点的谷分裂（VS）对于硅自旋量子位的性能和可扩展性起着重要作用。在本文中，我们研究了 SiGe/Si/SiGe 异质结构的 VS 作为硅量子点尺寸和位置的函数。我们使用有效质量方法来描述现实系统，该系统考虑了 Si/SiGe 界面的浓度波动以及界面粗糙度。我们预测，量子点的尺寸是增强VS的重要参数，它还可以引起无序主导状态到确定性增强状态之间的转变。分析当我们沿特定方向移动量子点时 VS 如何变化，我们发现量子点的尺寸可用于减少 VS 的变化，这与电荷/自旋穿梭相关。