Storage and retrieval of light pulses in atomic media with "slow" and "fast" light

We report experimental evidence that light storage, understood as the controlled release of a light pulse by an atomic sample dependent on the past presence of a writing pulse, is not restricted to small-group-velocity media but can also occur in a negative-group-velocity medium. We present a numerical modeling in close agreement with our observations and a simple physical picture applicable to light storage experiments in both 'slow' and 'fast' light media.