Robust and localised control of a 10-spin qubit array in germanium

Abstract

Abstract Quantum computers require the systematic operation of qubits with high fidelity. For holes in germanium, the spin-orbit interaction allows for electric, fast and high-fidelity qubit gates. However, the strong g-tensor anisotropy of holes in germanium and their sensitivity to the operational and environmental conditions challenge the operation of large qubit arrays. Here, we investigate a two-dimensional 10-spin qubit array with single-qubit gate fidelities above 99%, and obtain surprisingly uniform qubit properties. By tuning the hole occupation, we demonstrate control over the spin susceptibility, enabling fast plunger gate driving with Rabi frequencies consistently above 1.45 MHz/ (mV ⋅ T). Moreover, we probe the locality of electric dipole spin resonance and find that the configuration with three-hole occupancy driven by the associated quantum dot plunger gate reduces crosstalk, lowering it by an average factor of 2.5 to nearest neighbours, compared to single-hole plunger driving. Theoretical modelling points towards the pronounced anisotropy of p -like orbitals as the main mechanism with significant contributions through Coulomb interactions, giving directions for reproducible control of large qubit arrays.