An international research team has found a way to make light frequency conversion at the nanoscale 100 times more efficient. The new method is based on isolated dielectric nanoparticles supporting bound states in the continuum. Such states form when radiating field oscillations in the particle suppress each other. This way, the electromagnetic energy inside the particle can be locked securely. The obtained results can be used for further studies of nonlinear optics, in particular, for development of tiny light conversion devices. The research was published in Physical Review Letters on July 19, 2018, on the cover of the issue.