2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/17314We have investigated the far-infrared response of quantum dots in modulation doped GaAs heterostructures. We observe novel modes at frequencies below the center-of-mass Kohn mode. Comparison with Hartree-RPA calculations show that these modes arise from the flattened potential in our field-effect confined quantum dots. They reflect pronounced relative motion of the charge density with respect to the center-of-mass.8 pages, LaTeX with integrated 6 PostScript figuresMesoscale and Nanoscale Physicstext