Correction to: Nature Physics https://doi.org/10.1038/s41567-021-01276-2, published online 9 June 2021.

In the version of this News & Views article originally published online, in ref. 1, the URL was missing the text ‘10.1038/’ and should have read ‘https://doi.org/10.1038/s41586-021-03537-9’. All versions of the article have been amended.