Correction to: Nature Physics https://doi.org/10.1038/s41567-020-01051-9, published online 1 October 2020.

In the version of this Feature originally published, in the piece ‘A ghost-like quasiparticle’, the first sentence of the fourth paragraph, “A dipolar quantum gas was first created in 2012, and six years later, Lauriane Chomaz and colleagues eventually reported the observation of the roton excitation”, was incorrect. It should have been “While a dipolar quantum gas was first created in 2005, the fabrication of a sufficiently dipolar condensate of lanthanide atoms took longer to achieve and, eventually in 2018, Lauriane Chomaz and colleagues reported the observation of the roton excitation”. The online versions of the Feature have been amended.