Correction to: Nature https://www.nature.com/articles/s41586-019-0897-9, published online 06 February 2019.
Two references1,2 were inadvertently omitted from this Article. They have been added as refs 12 and 14 at the end of the sentence “Recently, photonic systems have emerged as a platform of interest for the exploration of synthetic quantum matter.” in the original Article. Subsequent references are renumbered accordingly.
1.Hartmann, M. J., Brandão, F. G. S. L. & Plenio, M. B. Strongly interacting polaritons in coupled arrays of cavities. Nat. Phys. 2, 849–855 (2006).
2.Angelakis, D. G., Santos, M. F. & Bose, S. Photon blockade induced Mott transitions and XY spin models in coupled cavity arrays. Phys. Rev. A 76, 031805 (2007).