Exciton droplets in zero dimensional systems in a magnetic field

The emission spectrum of self-assembled InGaAs/GaAs quantum dots filled with up to 10 excitions is measured in magnetic fields up to 13 Tesla. The spectrum shows a number of peaks which split and rearrange with the magnetic field. The behaviour of the spectrum with carrier density and magnetic field is compared with detailed calculations. The model allows us to interpret our results in terms of coherent many-exciton states and their destruction by the magnetic field. The level structure of the spectra is related to the shell structure and collective excitations of many-excition droplets in these artificial atoms.