Publisher Correction | Published:

Publisher Correction: A primary radiation standard based on quantum nonlinear optics

Correction to: Nature Physics, published online 4 March 2019.

In the version of this Letter originally published, in equation (3) a superscript ‘2’ was mistakenly placed inside the square root sign; instead it should have been outside as shown below:

$${\cal{N}} = \left( {c^{ - 1}\;L\;\chi ^{\left( 2 \right)}E_{\mathrm{p}}} \right)^2{\sqrt {\omega \omega _{\mathrm{i}}{\mathrm{/}}\left( {nn_{\mathrm{i}}} \right)}}^2{\mathrm{sinc}}^2\left( {{\mathrm{\Delta }}\kappa L{\mathrm{/}}2} \right)$$

This error has now been corrected in the online versions.

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Correspondence to Samuel Lemieux.

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