Correction to: Nature https://doi.org/10.1038/s41586-019-1110-x, published online 17 April 2019.

In the Methods section of this Letter, owing to a typesetting error, the equations of motion using the Heisenberg picture were incorrectly shown as:

$${\hat{\dot{a}}}_{k}=\frac{i}{\hbar }\left[{\hat{H}}_{{\rm{int}}},{\hat{a}}_{k}\right]=-i{n}_{{\rm{\Omega }}}\,g\left({\hat{a}}_{k-1}+{\hat{a}}_{k+1}\right)$$

instead of as:

$${\dot{{ {\hat{a}} }}}_{k}=\frac{i}{\hbar }\left[{\hat{H}}_{{\rm{int}}},{\hat{a}}_{k}\right]=-i\sqrt{{n}_{{\rm{\Omega }}}}g\left({\hat{a}}_{k-1}+{\hat{a}}_{k+1}\right)$$

This has been corrected online.