Storage and Release of Subradiant Excitations in a Dense Atomic Cloud

We report the observation of subradiance in dense ensembles of cold Rb87 atoms operating near Dicke's regime of a large number of atoms in a volume with dimensions smaller than the transition wavelength. We validate that the atom number is the only cooperativity parameter governing subradiance. We probe the dynamics in the many-body regime and support the picture that multiply excited subradiant states are built as a superposition of singly excited states that decay independently. Moreover, we implement an experimental procedure to release the excitation stored in the long-lived modes in a pulse of light. This technique is a first step towards the realization of tailored light storing based on subradiance.