Correction to: Nature Physics https://doi.org/10.1038/s41567-020-0860-6, published online 9 March 2020.

In the version of this News & Views article originally published, in ref. 3, the URL was missing an ‘s’ and should have read ‘https://doi.org/10.1038/s41567-020-0790-3’, also ‘(2019)’ should have been ‘(2020)’. The online versions of the article have been amended.