Correction to: Nature Photonics https://doi.org/10.1038/s41566-018-0144-1, published online 16 April 2018.

In the version of this Article originally published, in the Data availability section, ‘https://doi.org/10.5281/zenodo.1170059Zenodo’ was incorrect and should have read ‘https://doi.org/10.5281/zenodo.1170059’. This has now been corrected in the online versions.