Correction to: Nature Communications https://doi.org/10.1038/s41467-017-01999-y, published online 22 November 2017

The original version of this Article contained an error in Fig. 3a, in which the delay axis was incorrectly labeled in increments of 0.5 ps instead of the correct 0.2 ps. This has been corrected in both the PDF and HTML versions of the Article.