Coupling between LO phonons and electronic excitations of quantum dots

The far-infrared response of self-assembled ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ quantum dots located a distance from a two-dimensional ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ interface has been studied as a function of magnetic field. An avoided crossing at about 45 meV, which involves the lowest electronic transition of the dots, has been observed. Calculations of the interaction between the excitations of these quantum dots and the LO phonons of the ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ interface have been made, and the resulting splitting has been found to be in agreement with the experimental results. The calculated dependence of the magnitude of the splitting on the separation between the dots and the nearest interface is consistent with the experimental results.