Ann: Zero-Spin Silicon Project Successfully Completes Stage One, page-20

While these ²⁹Si nuclear spins could potentially be used as a resource for quantum computation⁴⁷, our findings suggest further improvement of the ²⁸Si isotopic enrichment may be crucial for building a truly scalable spin-based quantum processor.

Methods

Measurement setup

Figure 1a, b shows a scanning electron micrograph and a cross-sectional schematic of the sample used in this study. It is fabricated on top of a 900-nm-thick, isotopically enriched ²⁸Si epi layer with 800 p.p.m. residual ²⁹Si on a natural silicon substrate³⁴.

This is interesting, I was only familiar with their U enrichment work.

I see from this article in Dec 19, they were using 99.92% isotopic purity Si, so still a long way to come for SLX.

https://www.nature.com/articles/s41467-019-13416-7