Correction to: Nature Photonics https://doi.org/10.1038/s41566-021-00760-8, published online 8 February 2021.

In the version of this Article originally published, equation (1) was missing the equals sign after Im[f(x)]. In equation (2), \(\Re \left[ {\log \left( E \right)} \right]\) should have read Re[log(E)]. In equation (3), \(\Im \left[ {\log \left( E \right)} \right]\) should have read Im[log(E)]. These issues have now been corrected in the online versions of the Article.