Accessing the magnetic dipole and electric quadrupole of quantum dots with light

One of the central assumptions in quantum electrodynamics is to invoke the dipole approximation because (quantum) emitters are much smaller than the wavelength of light. The main consequence is that only the electric dipole plays a role in light-matter interactions at optical frequencies. In this paper we show that semiconductor quantum dots possess large magnetic-dipole and electric-quadrupole moments, which can be accessed with light. Moreover, quantum dots are capable of mediating electric-dipole, magnetic-dipole and electric-quadrupole interactions on dipole-allowed transitions and therefore are fundamentally different than atoms.