Quantum Dots Array on Ultra-Thin SOI Nanowires with Ferromagnetic Cobalt Barrier Gates for Enhanced Spin Qubit Control.

In this work we propose and demonstrate the integration of ferromagnetic nanosized cobalt barrier gates in quantum dots arrays on ultra-thin fully-depleted Silicon-On-Insulator (SOI) nanowires. This innovative structure enhances both driving and addressability, while minimizing decoherence fields for electron spin qubits. Charge noise spectra show sub-$1\cdot 10^{-6}\mathrm{e}^{2}$fflz values at 1 Hz, demonstrating a low noise impact from Cogates. Our double dot experimental data show stable quantum confinement at 10 mK and full multi-gate FET functionality. Based on calibrated magnetic simulations, we investigate and discuss the advantages of exploiting simultaneously elecmcal and ferromagnetic properties of gates. The record small achieved dot-magnet distance is in the range of 5 to 12 nm, with a footprint of the magnetic gates of 30x70nm ² on dots area, the smallest reported to date on a qubit structure, with a Rabi frequency of 282 MHz and qubit addressability of 1.069 GHz. This novel architecture paves the way to large-scale integration of qubits arrays with unprecedented magnetic control.