Correction to: Nature Photonics https://doi.org/10.1038/s41566-023-01255-4. Published 2 August 2023.

In the version of the article originally published, in the fifth paragraph, the equation 2k(ω) = k(2ω) incorrectly appeared as k(ω) = k(2ω). This has now been corrected in the HTML and PDF versions of the article.