Abstract: The direct search for dark matter has made remarkable progress over the past 15 years, driven in large part by the success of dual-phase xenon time projection chambers. Ever larger experiments have achieved unprecedented sensitivity only by pushing radioactive backgrounds to unprecedented low levels. One of the most persistent obstacles is posed by radioactive noble gases dissolved in the xenon - especially radon, whose decay products can mimic the signals of dark matter.

In this talk, I will introduce the XENONnT experiment and explain which methods were applied to suppress the radon background to a world-leading level of less than 1 microBq/kg. I will give an overview of current techniques for detecting and removing radon, and discuss how these methods pave the way toward even lower backgrounds in the next-generation XLZD experiment.