SiGe heteroepitaxial growth yields pristine host material for quantum dot qubits, but residual interface disorder can lead to qubit-to-qubit variability that might pose an obstacle to reliable SiGe-based quantum computing. By convolving data from scanning tunneling microscopy and high-angle annular dark field scanning transmission electron microscopy, we reconstruct 3D interfacial atomic structure and employ an atomistic multi-valley effective mass theory to quantify qubit spectral variability. The results indicate (1) appreciable valley splitting (VS) variability of ~50% owing to alloy disorder and (2) roughness-induced double-dot detuning bias energy variability of order 1–10 meV depending on well thickness. For measured intermixing, atomic steps have negligible influence on VS, and uncorrelated roughness causes spatially fluctuating energy biases in double-dot detunings potentially incorrectly attributed to charge disorder. Our approach yields atomic structure spanning orders of magnitude larger areas than post-growth microscopy or tomography alone, enabling more holistic predictions of disorder-induced qubit variability.

SiGe 异质外延生长为量子点量子位提供了原始的主体材料，但残留的界面无序可能导致量子位到量子位的可变性，这可能会对基于 SiGe 的可靠量子计算构成障碍。通过对来自扫描隧道显微镜和高角度环形暗场扫描透射电子显微镜的数据进行卷积，我们重建了 3D 界面原子结构，并采用原子多谷有效质量理论来量化量子位光谱变异性。结果表明 (1) 由于合金无序，谷分裂 (VS) 变异性约为 50%；(2) 粗糙度引起的双点失谐偏压能量变异性为 1-10 meV 数量级，具体取决于阱厚度。对于测量的混合，原子步骤对 VS 的影响可以忽略不计，并且不相关的粗糙度会导致双点失谐中空间波动的能量偏差，这可能被错误地归因于电荷无序。我们的方法产生的原子结构比单独的后生长显微镜或断层扫描跨越更大的数量级，从而能够更全面地预测无序引起的量子位变异性。