Photoluminescence of the incompressible Laughlin liquid: Excitons, chargedexcitons, and fractionally charged excitons

The photoluminescence (PL) of a two-dimensional electron gas (2DEG) in a hi gh magnetic field is studied as a function of the filling factor and the se paration d between the electron laver and the valence hole. Depending on th e magnitude of d relative to the magnetic length;,, two distinct regimes in the response of the 2DEG to the valence hole occur, with different element ary emission processes contributing to the PL spectrum. At d < gimel ("stro ng coupling" regime), the hole binds one or two electrons to form an excito n (X) or one of three possible charged exciton (X-) states, a spin-singlet or one of two spin-triplets. At d > gimel ("weak coupling" regime). the hol e decouples or binds one or two Laughlin quasi-electrons to form fractional ly charged excitons (FCXs). The binding energies as well as the emission en ergies and intensities of all X- and FCX states are calculated.