Hence, this is a challenging inverse design problem, as only a few materials in the database have the desired properties. Here, our experiment is the quantum calculation, and we typically assume that we can evaluate hundreds to thousands of materials in a reasonable time. From a machine-learning point of view, a set of thousands of materials is in a very low data regime. However, from an experimental point of view, this is a significant but sometimes doable effort. Of course, this is a somewhat arbitrary limit, and in Supplementary Fig. , we also give data for significantly fewer experiments.