Correction to: Nature Physics https://doi.org/10.1038/s41567-020-0940-7, published online 11 June 2020.

In the version of this Comment originally published, the second sentence of the section “The stellarator’s comeback and the rise of the private sector” referred to the “the 28th FEC”; it should have read “the 27th FEC”. All versions of the Comment have been amended.