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Abstract The realisation of a universal quantum computer will require the operation of many thousands to millions of coherently coupled qubits. The possibility of using existing industrial semiconductor fabrication techniques and infrastructure for up-scaling and reproducibility makes silicon based spin qubits one of the most promising platforms to achieve this goal. The implementation of the up to now largest semiconductor based quantum processor was realised in a silicon/silicon-germanium heterostructure known for its low charge noise, long qubit coherence times and fast driving speeds, but the high structural complexity creates challenges for industrial implementations. Here we demonstrate quantum dots hosted in a natural Si/SiGe heterostructure fully fabricated by an industrial 300 mm semiconductor wafer process line from heterostructure growth to Co micromagnet monolithic integration. We report charge noise values below 2 μeV/ {Hz} Hz, spin relaxation times exceeding 1 s, and coherence times T₂^* T 2 * and T₂^H T 2 H of 1 μs and 50 μs respectively, for quantum wells grown using natural silicon. Further, we achieve Rabi frequencies up to 5 MHz and single qubit gate fidelities above 99%. In addition to scalability, the high reproducibility of the 300 mm processes enables the deterministic study of qubit metric dependencies on process parameters, which is essential for optimising qubit quality.
Koch et al. (Sat,) studied this question.