Correction to: Nature Photonics https://doi.org/10.1038/s41566-019-0429-z, published online 24 April 2019.

In the version of this News & Views article originally published, the final digit was missing from the doi to the linked article: ‘https://doi.org/10.1021/acs.nanolett.9b0018’ should have read ‘https://doi.org/10.1021/acs.nanolett.9b00187’. This has now been corrected in the online versions.