<< When a periodic waveform is subjected to small perturbations to its amplitude and phase, any nonlinearity in the system can lead to its fragmentation — a so-called modulation instability. The phenomenon often results in the formation of solitons — self-reinforcing solitary wave packets — aligned in a train >>
AA << found that [ in ultracold 7Li atoms ] solitons developed first in the centre of the condensate rather than at the edges, suggesting that the seed for the modulation instability is dominated by noise, which may be technical, thermal or quantum in origin >>
Yun Li. Ultracold gases. Search for the seed. doi:10.1038/nphys4172
Jason H. V. Nguyen, De Luo, Randall G. Hulet. Formation of matter-wave soliton trains by modulational instability. Science 2017, 356 (6336), 422–426. doi: 10.1126/science.aal3220. 28 Apr 2017.