Spin qubits are considered to be among the most promising candidates for building a quantum processor 1 . Group IV hole spin qubits have moved into the focus of interest due to the ease of operation and compatibility with Si technology 2;3;4;5;6 . In addition, Ge offers the option for monolithic superconductor-semiconductor integration. Here we demonstrate a hole spin qubit operating at fields below 10 mT, the critical field of Al, by exploiting the large out-ofplane hole g-factors in planar Ge and by encoding the qubit into the singlet-triplet states of a double quantum dot 7;8 . We observe electrically controlled X and Z-rotations with tunable frequencies exceeding 100 MHz and dephasing times of 1 µs which we extend beyond 15 µs with echo techniques. These results show that Ge hole singlet triplet qubits outperform their electronic Si and GaAs based counterparts in speed and dephasing time, respectively. In addition, their rotation frequency and coherence time are on par with Ge single spin qubits, but they can be operated at much lower fields underlining their potential for on chip integration with superconducting technologies.

Hybrid semiconductor-superconductor devices hold great promise for realizing topological quantum computing with Majorana zero modes [1,2,3,4,5,6,7]. However, multiple claims of Majorana detection, based on either tunneling [8,9,10,11,12] or Coulomb spectroscopy [13,14], remain disputed.Here we devise an experimental protocol that allows to perform both types of measurements on the same hybrid island by adjusting its charging energy via tunable junctions to the normal leads. This method reduces ambiguities of Majorana detections by checking the consistency between Coulomb spectroscopy and zero bias peaks in non-blockaded transport. Specifically we observe junction-dependent, even-odd modulated, singleelectron Coulomb peaks without concomitant lowbias peaks in tunneling spectroscopy. We provide a theoretical interpretation of the experimental observations in terms of low-energy, longitudinallyconfined, island states rather than overlapping Majorana modes. Our method highlights the importance of combined measurements on the same device for the identification of topological Majorana bound states.

Hybrid semiconductor-superconductor devices hold great promise for realizing topological quantum computing with Majorana zero modes. However, multiple claims of Majorana detection, based on either tunneling or Coulomb spectroscopy, remain disputed. Here we devise an experimental protocol that allows to perform both types of measurements on the same hybrid island by adjusting its charging energy via tunable junctions to the normal leads. This method reduces ambiguities of Majorana detections by checking the consistency between Coulomb spectroscopy and zero bias peaks in non-blockaded transport. Specifically we observe junction-dependent, even-odd modulated, single-electron Coulomb peaks without concomitant low-bias peaks in tunneling spectroscopy. We provide a theoretical interpretation of the experimental observations in terms of low-energy longitudinallyconfined island states rather than overlapping Majorana modes. Our method highlights the importance of combined measurements on the same device for the identification of topological Majorana bound states.