  We study the evolution of photoluminescence (PL) from homogeneous and
inhomogeneous ensembles of a few coupled QDs. We discuss the relation between
signals from a given QD ensemble under strong and weak excitation (full
inversion and linear response regimes): A system homogeneous enough to manifest
superradiant emission when strongly inverted shows a non-exponential decay of
the PL signal under spatially coherent weak excitation. In an inhomogeneous
ensemble the PL decay is always nearly exponential with a qualitatively
different form of the time dependence in the two excitation regimes and with a
higher rate under weak excitation.
