Observation of quantum shock waves created with ultra- compressed slow light pulses in a Bose-Einstein condensate.

We have used an extension of our slow light technique to provide a method for inducing small density defects in a Bose-Einstein condensate. These sub- resolution, micrometer-sized defects evolve into large-amplitude sound waves. We present an experimental observation and theoretical investigation of the resulting breakdown of superfluidity, and we observe directly the decay of the narrow density defects into solitons, the onset of the "snake" instability, and the subsequent nucleation of vortices.