Two-dimensional electron gases have been the subject of research for decades. Modulation doped
GaAs quantum wells in the absence of magnetic fields exhibit interesting many-body physics such as
the Fermi edge singularity or Mahan exciton and can be regarded as a collective excitation of the system.
Under high magnetic fields Landau levels form which have been studied using transport and optical
measurements. Nonlinear coherent two-dimensional Fourier transform (2DFT) spectroscopy however
provides new insights into these systems. We present the 2DFT spectra of Mahan Excitons associated
with the heavy-hole and light-hole resonances observed in a modulation doped GaAs/AlGaAs single
quantum well . These resonances are observed to be strongly coupled through many-body interactions.
The 2DFT spectra were measured using co-linear, cross-linear, and co-circular polarizations and reveal
striking differences. Furthermore, 2DFT spectra at high magnetic fields performed at the National High
Magnetic Field Lab (NHMFL) in Tallahassee, Florida will be discussed. The spectra exhibit new
features and peculiar line shapes suggesting interesting underlying physics.
 J. Paul, C. E. Stevens, C. Liu, P. Dey, C. McIntyre, V. Turkowski, J. L. Reno, D. J. Hilton, and D.
Karaiskaj, Phys. Rev. Lett.116, 157401 (2016).
Denis Karaiskaj, "From Mahan excitons to Landau levels at high magnetic fields: 2DFT spectroscopy reveals hidden quantum correlations (Conference Presentation)," Proc. SPIE 10102, Ultrafast Phenomena and Nanophotonics XXI, 1010210 (Presented at SPIE OPTO: February 01, 2017; Published: 19 April 2017); https://doi.org/10.1117/12.2254917.5391659176001.
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