  We report the creation of quasi-1D excited matter-wave solitons, "breathers",
by quenching the strength of the interactions in a Bose-Einstein condensate
with attractive interactions. We characterize the resulting breathing dynamics
and quantify the effects of the aspect ratio of the confining potential, the
strength of the quench, and the proximity of the 1D-3D crossover for the
2-soliton breather. We furthermore demonstrate the complex dynamics of a
3-soliton breather created by a stronger interaction quench. Our experimental
results, which compare well with numerical simulations, provide a pathway for
utilizing matter-wave breathers to explore quantum effects in large many-body
systems.
