Individual Sb donors in silicon as nuclear spin qudits: an introduction for ESR-STM people

Speaker: Evert Stolte

Affiliation:University of New South Wales

Abstract:

Individual donor atoms in silicon are a promising spin qubit platform for scalable quantum computing. The spin of an electron bound to a donor atom is relatively protected from decoherence, with recorded T₂^CPMG times of up to 0.5 seconds [1], while single-shot readout remains accessible with high fidelity through spin-to-charge conversion in a nanoelectronic device. At the same time, the nuclear spin of the donor atom boasts even longer coherence times, and can be measured indirectly via the electron spin, which also provides a means to interact between remote donor nuclei [2].

The recent addition of donors with high nuclear spin, like antimony (Sb) [3], offers a larger Hilbert space in a single device and has opened up opportunities to investigate fundamental quantum physics questions, as well as logical qubit encodings within the larger qudit state space.

In this talk, I intent to discuss the inner workings of our spin donor devices and give an overview of recent research directions in this field. As someone who recently transitioned from working on ESR-STM in the Otte Lab to working on donor spins in silicon in the group of Andrea Morello, I hope I can provide a familiar perspective and highlight interesting ideas for the ESR-STM community.

[1] Muhonen, J., Dehollain, J., Laucht, A. et al. Storing quantum information for 30 seconds in a nanoelectronic device. Nature Nanotech 9, 986–991 (2014).
[2] Holly G. Stemp et al., Scalable entanglement of nuclear spins mediated by electron exchange. Science 389, 1234-1238 (2025).
[3] Yu, X., Wilhelm, B., Holmes, D. et al. Schrödinger cat states of a nuclear spin qudit in silicon. Nat. Phys. 21, 362–367 (2025).