Correction to: Nature Physics https://doi.org/10.1038/s41567-020-01136-5, published online 28 January 2021.

This Letter was originally published online incorrectly without open access, whereas it is actually covered by an Open Access licence (CC BY 4.0). The copyright line in the PDF mistakenly read “© The Author(s), under an exclusive licence to Springer Nature Limited 2020” but should have been ‘© The Author(s) 2021’. Furthermore, Extended Data Table 1 was missing from the online PDF. These errors have now been amended in all versions of the Letter.