Hybrid semiconductor-superconductor devices in planar Germanium

While Ge was used for the realization of the first transistor at Bell labs in 1947, only recently has it moved into the focus of attention for its potential for quantum information [1]. In particular, hole gases in Ge/SiGe heterostructures can have high mobilities in combination with strong spin-orbit interaction and electrically tunable g-factors; therefore, planar Ge has emerged as a promising platform for scalable spin qubits. In addition, the recent realization of a proximity induced hard gap in planar Ge devices underlines its potential also for hybrid superconductor-semiconductor devices [2,3]. In this talk, I will report on our efforts in implementing circuit quantum electrodynamics experiments on Ge/SiGe heterostructures, in order to be able to move towards hybrid superconducting circuits [4,5].