Nature Communications 8:366 10.1038/s41467-017-00446-2; Article published online: 28 August 2017

This Article contains two typesetting errors. In the penultimate sentence of the first paragraph of the Results section, the equation should be ‘\(\alpha _0(\omega ) \propto \sqrt {\hbar \omega - \Delta } /\hbar \omega\)’, not ‘\(\alpha _0(\omega ) \propto \sqrt {\hbar \omega - \Delta /\hbar \omega }\)’. In Fig. 4a, the variable marking the top dashed line should be ‘\(E_{{\mathrm{H}}1}^{{\mathrm{DP}}}\)’, not ‘\(E_{{\mathrm{H}}2}^{{\mathrm{DP}}}\)’.