Magnetoexcitons and correlated electrons in quantum dots in a magnetic field

Magnetoexcitons interacting with strongly correlated electronic states in quantum dots in a strong magnetic field are studied. Exact calculations relate the absorption and emission of few-electron artificial atoms to magnetic-field-induced phase transitions between ``magic'' states. For large compact droplets, the coupling of magnetoexcitons to low-energy excitations (edge magnetorotons) leads to a strong enhancement of the oscillator strength at the Fermi level (Fermi edge singularity) both in absorption and in emission on acceptors. The condensation of edge magnetorotons signals the reconstruction of the droplet and is accompanied by different structures in the absorption spectrum. {} 1996 The American Physical Society.