In Si/SiGe heterostructures, the low-lying excited valley state seriously limits the operability and scalability of electron spin qubits. For characterizing and understanding the local variations in valley splitting, fast probing methods with high spatial and energy resolution are lacking. Leveraging the spatial control granted by conveyor-mode spin-coherent electron shuttling, we introduce a method for two-dimensional mapping of the local valley splitting by detecting magnetic field-dependent anticrossings of ground and excited valley states using entangled electron spin-pairs as a probe. The method has sub-μeV energy accuracy and a nanometer lateral resolution. The histogram of valley splittings spanning a large area of 210 nm by 18 nm matches well with statistics obtained by the established but time-consuming magnetospectroscopy method. For the specific heterostructure, we find a nearly Gaussian distribution of valley splittings and a correlation length similar to the quantum dot size. Our mapping method may become a valuable tool for engineering Si/SiGe heterostructures for scalable quantum computing.

在Si/SiGe异质结构中，低位激发谷态严重限制了电子自旋量子位的可操作性和可扩展性。为了表征和理解山谷分裂的局部变化，缺乏具有高空间和能量分辨率的快速探测方法。利用传送模式自旋相干电子穿梭所赋予的空间控制，我们引入了一种局部谷分裂的二维映射方法，通过使用纠缠电子自旋对作为检测方法来检测基态和激发谷态的磁场相关反交叉。探测。该方法具有亚μeV能量精度和纳米横向分辨率。跨越 210 nm x 18 nm 大面积的谷分裂直方图与通过已建立但耗时的磁谱方法获得的统计数据非常匹配。对于特定的异质结构，我们发现谷分裂的近高斯分布和与量子点尺寸相似的相关长度。我们的映射方法可能成为设计 Si/SiGe 异质结构以实现可扩展量子计算的宝贵工具。