With gate fidelities approaching the requirements for practical error corrections and significant progress in industrial processing, the next challenge for spin qubits is to identify a scalable architecture. A natural extension of current devices would be dense quantum dot arrays, which however suffer from crosstalk and severe wiring fanout problems. Coupling qubits over a longer range beyond nearest neighbours could address these issues and may be the key to scaling up. I will report on experiments on Si/SiGe devices that demonstrate reliable shuttling of individual electrons over micron-scale distances using only four signals independent of the transfer distance [arXiv:2108.00879]. Theoretical considerations indicate good prospects for maintaining spin coherence during shuttling [arXiv:2202.11793]. Building on this approach, we propose a scalable architecture that is compatible with available semiconductor technology and promises very favorable properties in terms of crosstalk, fidelities, operating frequency, tunability and wiring access as well as suitability for future cryoelectronic control. Detailed simulations support the feasibility of the proposal.
RWTH Aachen and Forschungszentrum Jülich
Scaling up via spin shuttling