Superradiance and Subradiance in an Inhomogeneously Broadened Ensemble of Two-Level Systems Coupled to a Low-QCavity

The collective spontaneous emission of a fully inverted inhomogeneously broadened ensemble of $N$ two-level systems coupled to a single-mode low-$Q$ cavity is investigated numerically using Monte Carlo wave function technique. An intrinsically bi-exponential emission dynamics is found when the time scales of superradiance ${\tau }_{\mathrm{sr}}$ and inhomogeneous dephasing $T_2^{*}\sim 1/\Delta {\omega }_{\mathrm{inh}}$ become comparable: a fast superradiant is followed by a slow subradiant decay. Experimental configurations using ensembles of quantum dots coupled to optical microcavities are proposed as possible candidates to observe the combined superradiant and subradiant energy relaxation.