  We study acoustic-phonon-induced relaxation of charge excitations in single
and tunnel-coupled quantum dots containing few confined interacting electrons.
The Full Configuration Interaction approach is used to account for the
electron-electron repulsion. Electron-phonon interaction is accounted for
through both deformation potential and piezoelectric field mechanisms. We show
that electronic correlations generally reduce intradot and interdot transition
rates with respect to corresponding single-electron transitions, but this
effect is lessened by external magnetic fields. On the other hand,
piezoelectric field scattering is found to become the dominant relaxation
mechanism as the number of confined electrons increases. Previous proposals to
strongly suppress electron-phonon coupling in properly designed single-electron
quantum dots are shown to hold also in multi-electron devices. Our results
indicate that few-electron orbital degrees of freedom are more stable than
single-electron ones.
