Bright gap solitons of atoms with repulsive interaction
  We report on the first experimental observation of bright matter-wave solitons for 87Rb atoms with repulsive atom-atom interaction. This counter intuitive situation arises inside a weak periodic potential, where anomalous dispersion can be realized at the Brillouin zone boundary. If the coherent atomic wavepacket is prepared at the corresponding band edge a bright soliton is formed inside the gap. The strength of our system is the precise control of preparation and real time manipulation, allowing the systematic investigation of gap solitons. 
B. Eiermann, Th. Anker, M.Albiez, M. Taglieber, P. Treutlein, K. P.   Marzlin, M. K. Oberthaler