Controlled Dicke subradiance from a large cloud of two-Level systems

Dicke superradiance has been observed in many systems and is based on constructive interferences
between many scattered waves. The counterpart of this enhanced dynamics, subradiance, is a destructive
interference effect leading to the partial trapping of light in the system. In contrast to the robust
superradiance, subradiant states are fragile, and spurious decoherence phenomena hitherto obstructed
the observation of such metastable states. We show that a dilute cloud of cold atoms is an ideal system to
look for subradiance in free space and study various mechanisms to control this subradiance.