Probing subradiant dynamics in cold atomic ensembles via population and emitted light measurements

In this Letter, we report on the time- and space-resolved measurement of subradiant excited state population in an ultra-cold atomic cloud of ¹⁷⁴Yb atoms. We use a <i>depletion</i> imaging technique that exploits the <i>Λ</i>-type internal energy structure to directly observe the time-resolved spatial distribution of excited state population. We characterize the decay dynamics of the subradiant modes using both the excited state population and scattered light intensity, finding good quantitative agreement with numerical predictions.