J. -H. Kim, J. Lee, G. T. Noe, Y. Wang, A. K. Wójcik, S. A. McGill, D. H. Reitze, A. A. Belyanin, J. Kono
We study light emission properties of a population-inverted 2D electron-hole plasma in a quantizing magnetic field. We observe a series of superfluorescent bursts, discrete both in time and energy, corresponding to the cooperative recombination of electron-hole pairs from different Landau levels. The emission energies are strongly renormalized due to many-body interactions among the photogenerated carriers, exhibiting red-shifts as large as 20 meV at 15 T. However, the magnetic field dependence of the lowest Landau level emission line remains excitonic at all magnetic fields. Interestingly, our time-resolved measurements show that this lowest-energy burst occurs only after all upper states become empty, suggesting that this excitonic stability is related to the `hidden symmetry' of 2D magneto-excitons expected in the magnetic quantum limit.
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http://arxiv.org/abs/1009.3067
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