  We fabricate Josephson field-effect-transistors in germanium quantum wells
contacted by superconducting aluminum and demonstrate supercurrents carried by
holes that extend over junction lengths of several micrometers. In
superconducting quantum point contacts we observe discretization of
supercurrent, as well as Fabry-Perot resonances, demonstrating ballistic
transport. The magnetic field dependence of the supercurrent follows a clear
Fraunhofer-like pattern and Shapiro steps appear upon microwave irradiation.
Multiple Andreev reflections give rise to conductance enhancement and evidence
a transparent interface, confirmed by analyzing the excess current. These
demonstrations of ballistic superconducting transport are promising for hybrid
quantum technology in germanium.
