Superconductivity in Planar Germanium Quantum Wells

The coupling of the superconducting macroscopic wave functions across a weak link has provided rich avenues for fundamental physics and technological advancements. Such weak links made from semiconductors provide further knobs such as spin-orbit coupling and Zeeman splitting to explore non-trivial spin textures and exotic states. Planar Ge confining hole states, compatible with Si foundry, has emerged as a technologically mature semiconducting platform [1]. Here, we demonstrate transparent coupling between superconductors and a Ge quantum well, with high magnetic field resilience. Investigating current distributions in the fabricated Josephson Junctions via the modulation of the superconducting phase difference provides insight into the underlying Andreev transport occurring through the semiconducting weak link. Our results pave the way towards the integration of already demonstrated spin qubits in planar germanium with induced superconductivity on the same platform. [1] Scappucci, G., et al. (2020). The germanium quantum information route. arXiv:2004.08133v1