Inhibited Recombination of Charged Magnetoexcitons
  Time-resolved photoluminescence measurements show that the decay time for charged excitons in a GaAs two-dimensional electron gas increases by an order of magnitude at high magnetic fields. Unlike neutral excitons, the charged exciton center-of-mass is spatially confined in a ``magnetically-adjustable quantum dot'' by the cyclotron orbit and the quantum well. The inhibited recombination is explained by a reduced phase coherence volume of the magnetically-confined charged excitons. 
H. Okamura, D. Heiman, M. Sundaram, and A.C. Gossard