Electron spins in Si are an attractive platform for quantum computation, backed with their scalability and fast, high-fidelity quantum logic gates. Despite the importance of two-dimensional integration with efficient connectivity between qubits for medium- to large-scale quantum computation, however, a practical device design that guarantees qubit addressability is yet to be seen. Here, we propose a practical 3 x 3 quantum dot device design and a larger-scale design as a longer-term target. The design goal is to realize qubit connectivity to the four nearest neighbors while ensuring addressability. We show that a 3 x 3 quantum dot array can execute four-qubit Grover's algorithm more efficiently than the one-dimensional counterpart. To scale up the two-dimensional array beyond 3 x 3, we propose a novel structure with ferromagnetic gate electrodes. Our results showcase the possibility of medium-sized quantum processors in Si with fast quantum logic gates and long coherence times.
@article{arxiv.2106.11124,
title = {Designs for a two-dimensional Si quantum dot array with spin qubit addressability},
author = {Masahiro Tadokoro and Takashi Nakajima and Takashi Kobayashi and Kenta Takeda and Akito Noiri and Kaito Tomari and Jun Yoneda and Seigo Tarucha and Tetsuo Kodera},
journal= {arXiv preprint arXiv:2106.11124},
year = {2021}
}