Nature Communications 8:251 doi:10.1038/s41467-017-00228-w; Article published online 15 August 2017

This Article contains typographical errors in Equation (2), where two division operators were omitted. The correct version of Equation (2) appears below

$$I\left( \omega \right) = I_0\frac{{\left[ {1 + \left( {\omega - \omega _0} \right)/q\Gamma } \right]^2}}{{1 + \left[ {\left( {\omega - \omega _0} \right)/\Gamma } \right]^2}}.$$