Correction to: Nature Photonics https://doi.org/10.1038/s41566-020-00725-3, published online 23 November 2020.

In the version of this Letter originally published, the x-axis label of Fig. 3f incorrectly read ‘LPP/vgr, κ (ps)’; it should have read ‘LPP/vgr, τ (ps)’. This has now been corrected in all versions of the Letter.