  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.
