Speaker: Alessandro Crippa (Institute of Science and Technology Austria)


Many materials are under study to realize a quantum processor for universal quantum computing. For implementations in the solid state domain, superconducting compounds and group IV semiconductor elements are among the most promising ones. Superconducting circuits have proven to overcome classical computation on specific tasks, while semiconductor qubits have gained interest due to the compatibility with industrial fabrication techniques and long coherence times, both key ingredients for scaling-up. The possibility of sharing the same material for both platforms would be a great technological advancement. Germanium (Ge) offers unique features in this respect. Here we demonstrate a Ge spin qubit operating at ultra-low magnetic field (< 1 mT) with coherence times up to 15 μs (https://arxiv.org/pdf/2011.13755.pdf). This not only makes our qubit compatible with Al-based superconducting electronics, but also opens the way to monolithic integration of superconducting qubits on proximitized Ge and semiconducting spin qubits.