The energy and photoluminescence (PL) spectra of a two-dimensional electron
gas (2DEG) interacting with a valence-band hole are studied in the high-ma
gnetic-field limit as a function of the filling factor v and the separation
d between the electron and hole layers. For d smaller than the magnetic le
ngth lambda, the hole binds one or more electrons to form neutral (X-0) or
charged (X-) excitons, and PL probes the lifetime and binding energies of t
hese complexes rather than the original correlations of the 2DEG. The low-l
ying states can be understood in terms of Laughlin-type correlations among
the constituent negatively charged Fermions (electrons and X(-,)s). For d,
large compared to lambda, the electron-hole interaction is not strong enoug
h to bind a full electron, and fractionally charged excitons hQE(n) (bound
states of the hole and one or more Laughlin quasielectrons) are formed. The
PL selection rule associated with rotational invariance (conservation of L
) is only weakly violated in the interacting plasma, and the position and o
scillator strengths of PL lines can be predicted and compared with numerica
l calculations. (C) 2001 Elsevier Science B.V. All rights reserved.