发表机构
University of Konstanz（康斯坦茨大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文理论研究了Si/SiGe异质结构中自旋穿梭的谷动力学，发现特定速度下可抑制谷激发实现相干穿梭，并提出基于部分Landau-Zener模型的高效保真度提升策略。
AI 中文摘要
谷激发被认为是Si/SiGe异质结构中相干自旋穿梭的最大挑战之一。在本工作中，我们通过考虑由移动量子点的两个低能谷态构成的两能级系统，从理论上研究了Si/SiGe异质结构中自旋穿梭过程中的谷动力学。我们假设电子初始处于谷基态，并分析了该态在穿梭过程中的演化。我们发现，根据穿梭速度的不同，系统可以处于三种不同的状态。在其中的一种状态下，即使存在谷激发，量子信息也能得以保持，从而允许与穿梭距离无关的相干自旋穿梭。这种状态在穿梭速度为每秒数十米时获得，这是一个理想的区域，其中诸如自旋-谷热点和空间变化的自旋分裂等退相干机制可以被抑制。这一结果与最近的实验工作相符，该实验在快速且长距离穿梭后获得了高保真度的自旋穿梭。我们还提出了基于部分Landau-Zener模型的策略来提高谷穿梭保真度，发现该策略比先前基于标准Landau-Zener模型的策略要高效得多。
英文摘要
Valley excitations are considered one of the biggest challenges for a coherent spin shuttling in Si/SiGe heterostructures. In this work we theoretically investigate the valley dynamics during spin shuttling in a Si/SiGe heterostructure by considering a two-level system given by the two low-lying valley states of the mobile quantum dot. We assume that the electron is initially in the valley ground state and analyze the evolution of this state during shuttling. We find that, depending on the shuttling velocity, the system can be in three distinct regimes. In one of these regimes, the quantum information is preserved even in the presence of the valley excitations, allowing for coherent spin shuttling independently of the shuttling distance. This regime is obtained for a shuttling velocity of tens of m/s, a desired regime where dephasing mechanisms, such as spin-valley hotspots and spatially varying spin splitting, can be suppressed. This result is in accordance with recent experimental work that obtained a high spin shuttling fidelity after a fast and long shuttling. We also propose strategies based on the Partial Landau-Zener model to enhance the valley shuttling fidelity, which was found to be much more efficient than previously proposed strategies based on the standard Landau-Zener model.
