Scientists from the Cavendish Laboratory at the University of Cambridge and the University of St Andrews in the UK have discovered that luminescent molecules collectively act and flash synchronously in gaps less than one nanometer wide between gold nanoparticles, much like fireflies. This discovery challenges long-standing assumptions about the formation of optical coherence and opens up new possibilities for highly sensitive sensors operating at room temperature, molecular photonics, and future quantum technologies. The related paper has been published in the latest issue of the journal Nature Nanotechnology.