Conveyor-mode shuttling is a key approach for implementing intermediate-range coupling between electron-spin qubits in quantum dots. Initial implementations are encouraging; however, long shuttling trajectories are guaranteed to encounter regions of low conduction-band valley energy splittings, due to the presence of random-alloy disorder in Si/SiGe quantum wells. Here, we theoretically explore two schemes for avoiding valley-state excitations at these valley-splitting minima, by allowing the electrons to detour around them. A multichannel shuttling scheme allows electrons to tunnel between parallel channels, while a two-dimensional (2D) shuttler provides full omnidirectional control. Using simulations, we estimate shuttling fidelities in these two schemes, obtaining a clear preference for the 2D shuttler. Based on such encouraging results, we propose a modular qubit architecture based on 2D shuttling, which enables all-to-all connectivity within qubit plaquettes and high-fidelity communication between different plaquettes.
@article{arxiv.2412.09574,
title = {Omnidirectional shuttling to avoid valley excitations in Si/SiGe quantum wells},
author = {Róbert Németh and Vatsal K. Bandaru and Pedro Alves and Emma Brann and Owen M. Eskandari and Hudaiba Soomro and Avani Vivrekar and M. A. Eriksson and Merritt P. Losert and Mark Friesen},
journal= {arXiv preprint arXiv:2412.09574},
year = {2026}
}