Observation of attraction between dark solitons
  We demonstrate a dramatic change in the interaction forces between dark solitons in nonlocal nonlinear media. We present what we believe is the first experimental evidence of attraction of dark solitons. Our results indicate that attraction should be observable in other nonlocal systems, such as Bose-Einstein condensates with repulsive long-range interparticle interaction. 
Alexander Dreischuh, Dragomir N. Neshev, Dan E. Petersen, Ole Bang,   and Wieslaw Krolikowski