Optical absorption of a many-polaron system confined in a quantum dot

The ground state energy and the optical absorption spectra are obtained for N electrons interacting with each other and with the longitudinal optical (LO) phonons at an arbitrary electron–phonon coupling strength in a parabolic confinement potential. In order to account for the fermion statistics, we use the path integral formalism for identical particles. The approach is at present limited to closed shells. In the case of strong electron–phonon interaction, a ferromagnetic-to-nonmagnetic transition is shown to occur between states with different total spin of the system. This transition is revealed through the optical absorption spectra and should be experimentally observable. When the confinement frequency parameter is in resonance with the LO phonon frequency, strong mixing between zero-phonon and one-phonon states is manifested in the absorption spectrum.