  Superconductors and semiconductors are crucial platforms in the field of
quantum computing. They can be combined to hybrids, bringing together physical
properties that enable the discovery of new emergent phenomena and provide
novel strategies for quantum control. The involved semiconductor materials,
however, suffer from disorder, hyperfine interactions or lack of planar
technology. Here we realise an approach that overcomes these issues altogether
and integrate gate-defined quantum dots and superconductivity into a material
system with strong spin-orbit coupling. In our germanium heterostructures,
heavy holes with mobilities exceeding 500,000 cm$^2$/Vs are confined in shallow
quantum wells that are directly contacted by annealed aluminium leads. We
demonstrate gate-tunable superconductivity and find a characteristic voltage
$I_cR_n$ that exceeds 10 $\mu$V. Germanium therefore has great promise for fast
and coherent quantum hardware and, being compatible with standard
manufacturing, could become a leading material in the quantum revolution.
