Energy spectra of fractional quantum Hall systems in the presence of a valence hole - art. no. 045303

The energy spectrum of a two-dimensional electron gas (2DEG) in the fractio nal quantum Hall regime interacting with an optically injected valence band hole is studied as a function of the filling factor z' and the separation d between the electron and hole layers. The response of the 2DEG to the hol e changes abruptly at d of the order of the magnetic length lambda. At d < <lambda>, the hole binds electrons to form neutral (X) or charged (X-) exci tons, and the photoluminescence (PL) spectrum probes the lifetimes and bind ing energies of these states rather than the original correlations of the 2 DEG. The "dresscd exciton" picture (in which the interaction between an exc iton and the 2DEG was proposed to merely enhance the exciton mass) is quest ioned. Instead, the low energy states are explained in terms of Laughlin co rrelations between the constituent fermions (electrons and X-'s) and the fo rmation of two-component incompressible fluid states in the electron-hole p lasma. At d > 2 lambda, the hole binds up to two Laughlin quasielectrons (Q E) of the 2DEG to form fractionally charged excitons hQE(n). The previously found "anyon exciton" hQE(3) is shown to be unstable at any value of d. Th e critical dependence of the stability of different hQE(n), complexes on th e presence of QE's in the ?,DEG leads to the observed discontinuity of the PL spectrum at v = 1/3 or 2/3.