Integrating high-spin antimony donors with MOS quantum dots in silicon, Part 1: Donor-dot coupling

High-spin nuclear systems are a promising platform for encoding high-dimensional quantum information. Recent work has demonstrated full control over the high-spin antimony (123Sb) donor in silicon [1] and the creation and manipulation of Schrödinger cat states, which can be used for logical qubit encodings [2]. Due to limits on the code distance imposed by the spin quantum number, such cat-encoded logical qubits will need to be further embedded within an outer code to reduce logical error rates. It will also be essential to perform mid-circuit measurements and real-time error correction. Both challenges can be addressed by integrating 123Sb donors with gate-defined quantum dots.

We present a new architecture that integrates a single 123Sb donor with gate-defined, metal-oxide-semiconductor (MOS) quantum dots. We experimentally demonstrate full control over the 123Sb nucleus, and both the donor and dot electron spins. We also measure exchange interactions of J = 50 MHz between the donor and dot electrons when operating in the two-electron regime. These results open a new pathway for next-generation donor-dot devices that allow greater flexibility and scalability of quantum devices based on high-spin logical encodings.

[1] Fernández de Fuentes, I. et al. Nature Communications 15, 1380 (2024).

[2] Yu, X. et al. Nature Physics 21, 362–367 (2025).