Hidden quasisymmetry in the optical absorption of quantum dot nanorings

We report numerical results demonstrating the existence of a hidden dynamical quasisymmetry in the optical absorption of finite nanorings consisting of metallic quantum dots described by means of the extended Hubbard model for closed shells, causing, out of a multitude of transitions allowed by spatial symmetry, all but one to be practically forbidden. We show that, by shining only a part of the nanoring, one can get more information than by irradiating the whole nanoring, and suggest that experimentalists apply this method to measure optical absorption spectra.