Si/SiGe中自旋谷热点附近Loss-DiVincenzo量子比特的本征自旋轨道驱动增强
Enhanced intrinsic spin-orbit driving of a Loss-DiVincenzo qubit near the spin-valley hotspot in Si/SiGe
AI总结：
本文在Si/SiGe自旋谷热点附近实现i-SOC驱动的Loss-DiVincenzo量子比特，观测到拉比频率增强及不对称性等特性，为完善自旋谷物理理论模型提供实验依据。
AI中文摘要：
在大多数基于Si/SiGe的自旋量子比特实现方案中，高保真度单量子比特门是通过微磁体实现的，微磁体可借助合成自旋轨道耦合（s-SOC）实现电自旋偶极共振。相比之下，硅中的本征自旋轨道耦合（i-SOC）通常被认为很弱。但理论预测，在Si/SiGe异质结构中，当塞曼劈裂接近谷劈裂且界面因缺陷降低对称性时，本征自旋轨道耦合会显著增强。本文中，我们演示了一种在该所谓自旋谷热点附近由i-SOC驱动的Si/SiGe Loss-DiVincenzo量子比特，具体通过同时扫描磁场和量子点位置，表征拉比频率随热点能量失谐的变化关系。我们观察到热点附近拉比频率的预测增强效应，同时发现其存在偏离现有理论模型的不对称性，以及热点附近Chevron图案的畸变。虽然我们实现了98.6%的平均单量子比特Clifford保真度，但谷劈裂的强可变性可能会阻碍基于i-SOC的控制作为可扩展操作策略的应用；不过，理解其效应对实现可重复的高保真控制仍具有重要意义。我们的结果为完善当前Si/SiGe异质结构自旋谷物理的理论模型提供了实验依据。
英文摘要：
In most Si/SiGe-based spin qubit implementations, high-fidelity single-qubit gates are achieved using micromagnets, which enable the use of electric spin dipole resonance via synthetic spin-orbit coupling (s-SOC). In contrast, intrinsic spin-orbit coupling (i-SOC) in silicon is generally considered to be weak. However, in Si/SiGe heterostructures, theory predicts a substantial enhancement when the Zeeman splitting approaches the valley splitting if symmetry is reduced by an imperfect interface. Here, we demonstrate a Si/SiGe Loss-DiVincenzo qubit driven by i-SOC close to this so-called spin-valley hotspot. In particular, we characterize the Rabi frequency as a function of the energy detuning from the hotspot by sweeping both the magnetic field and quantum dot position. We observe the predicted enhancement of the Rabi frequency near the hotspot, but also find an asymmetry that deviates from existing theoretical models as well as distortions of the Chevron patterns near the hotspot. While we achieve an average single-qubit Clifford fidelity of 98.6 %, the strong variability of the valley splitting may impede the use of i-SOC-based control as a scalable operational strategy; understanding its effect is nevertheless important for reproducible high-fidelity control. Our results provide an empirical basis for refining current theoretical models of spin-valley physics in Si/SiGe heterostructures.
