Theory of far-infrared absorption of a negatively charged exciton in a quantum dot

We present a theory of the far-infrared (FIR) absorption spectra of a negatively charged exciton X- confined in a parabolic quantum dot and subject to an external magnetic field. The absorption spectra of the trion exhibit a set of characteristic lines and line anticrossings, sensitive both to the details of electron and hole confinement and the Coulomb interactions among carriers. This is in contrast to the case of dots containing electrons only, where the FIR absorption probes only the excitations of the center-of-mass of the system and is insensitive to interaction effects.