Renormalization of electron energy in 0D systems due to depolarization shift

A giant level shift, resulting from the interaction of an electron in a spherical quantum dot with zero-point oscillations of confined modes of the electric field, is divulged. This electron potential energy renormalization depends on the dot radius which has to show up in experiment. The size scaling of the depolarization effect is computed semiclassically. A change of the optical properties of the matrix surrounding the dot also provides a method with which to study the shift experimentally.