AI 中文总结
研究旨在增强硅锗异质结构的谷分裂以用于自旋量子比特。通过结合一维紧束缚理论的器件尺度模拟及非传统设计方法，将谷分裂推至1到5毫电子伏特，为可扩展硅/硅锗自旋量子比特器件发展提供路径，有望解决谷分裂问题。
AI 中文摘要
实现远超过电子热能的谷分裂并避免谷激发对于门定义的硅自旋量子比特的一致初始化、操作和读出至关重要。在这项工作中，我们提出了一种器件级优化策略，将谷分裂推至1到5毫电子伏特之间，远超几乎所有先前理论研究报道的值。通过一维紧束缚理论结合原子合金无序的器件尺度模拟，我们证明所提方法能产生大的谷分裂且在无序实现中分布紧密，这是大规模可重复量子比特性能的关键要求。该方法基于一种非传统的硅/硅锗异质结构设计，结合窄量子阱、小锗尖峰和纯锗帽。我们用有针对性的原子密度泛函理论计算证实了这些预测。这些结果为可扩展的硅/硅锗自旋量子比特器件提供了一条清晰的前进道路，若通过实验实现，可有效消除谷分裂这一大规模硅锗基量子处理器的现存问题。
英文摘要
Achieving valley splittings well in excess of the thermal energy of electrons and avoiding valley excitations is essential for the consistent initialization, operation and readout of gate-defined Si spin qubits. In this work, we present a device-level optimization strategy for pushing valley splittings to between 1 and 5 meV, well beyond values reported in nearly all previous theoretical studies. Using device-scale simulations that incorporate atomistic alloy disorder through a 1D tight-binding theory, we demonstrate that our proposed approach yields large valley splittings with a tight distribution across disorder realizations, a key requirement for reproducible qubit performance at scale. The approach rests on an unorthodox Si/SiGe heterostructure design combining a narrow quantum well, a small Ge spike, and a pure-Ge cap. We corroborate these predictions with targeted atomistic density functional theory calculations. These results offer a clear path forward for scalable Si/SiGe spin qubit devices and, if realized experimentally, effectively eliminate valley splitting as an existential problem for large scale SiGe-based quantum processors.
Comments9 pages, 10 figures
