Correction to: Nature Photonics https://doi.org/10.1038/s41566-020-0690-1, published online 14 September 2020.

In the version of this Article originally published online, in equation (1), there was a superfluous equal sign following the term \(\frac{{{\mu}_0}}{{4\uppi}}\); the equation should have read

$${\mathbf{B}}\left( {\mathbf{r}} \right) = \frac{{{\mu}_0}}{{4\uppi}} {\int} {{\int} {{\int} {\frac{{\left( {{\mathbf{J}}{\mathrm{d}}V} \right) \times {\mathbf{r}}^{\prime} }}{{|{\mathbf{r}}^{\prime} |^3}}} } } .$$
(1)

All versions of the Article have been amended.