Correction to: Nature Nanotechnology https://doi.org/10.1038/s41565-019-0488-9, published online 8 July 2019.

In the version of this Letter originally published, the second, third and fourth exponential terms in equation (3) were incorrect; the corrected equation is shown below.

$$\begin{array}{c}{\mathrm{n}}_{\mathrm{S}} = \frac{1}{{\sqrt {2\pi } \sigma _{\mathrm{S}}}}e^{ - \frac{{(|S_{21}| - \mu _{\mathrm{S}})^2}}{{2\sigma _{\mathrm{S}}^2}}}e^{-\frac{{t_{{\mathrm{int}}}}}{{T_1}}}\\ + \frac{1}{{\sqrt {2\pi } \sigma _{\mathrm{S}}}}\frac{{t_{{\mathrm{int}}}}}{{T_1}}{\int}_{\mu _{\mathrm{T}}}^{\mu _{\mathrm{S}}} {\frac{1}{{\mu _{\mathrm{S}} - \mu _{\mathrm{T}}}}}e^{{ - \frac{{x - \mu _{\mathrm{T}}}}{{\mu _{\mathrm{S}} - \mu _{\mathrm{T}}}}} \ \frac{t_{\mathrm{int}}}{{T_1}}}e^{-\frac{{(|S_{21}| - x)^2}}{{2\sigma _{\mathrm{S}}^2}}}{\mathrm{d}}x\end{array}$$
(3)

The correct equation was used for data analysis. The online versions have been amended.