Correction to: Nature Physics https://doi.org/10.1038/s41567-020-01070-6, published online 23 November 2020.

In the version of this Letter originally published online, the author J. M. Yeomans was incorrectly affiliated with ‘Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark’, instead of ‘Rudolf Peierls Centre for Theoretical Physics, Clarendon Laboratory, University of Oxford, Oxford, UK’. This affiliation has now been added, and other footnotes renumbered accordingly, in all versions of the Letter.