Localization and many-body interactions in the quantum Hall effect determined by polarized optical emission

Polarization analysis of optical emission from the electron gas in GaAs single quantum wells discriminates the separate contributions from spin-split electron states. In the extreme quantum limit, the vastly different electron populations of these two states allows the study of many-body phenomena in the presence of localization. Reduction in electron screening of the hole at =1 appears to cause energy shifts in narrow quantum wells, while electron-hole binding dominates in wider wells. Evidence of a technique probing the spin-configuration of fractional quantum Hall states is also presented.