Snake instability of ring dark solitons in toroidally trapped Bose-Einstein condensates

We show by numerically solving the Bogoliubov-de Gennes equations and numerically integrating the Gross-Pitaevskii equation that the onset of the snake instability of ring dark solitons requires a broken symmetry. We elucidate explicitly the connection between imaginary Bogoliubov modes and the snake instability, predicting the number of vortex-antivortex pairs produced. In addition, we propose a simple model to give a physical motivation as to why the snake instability takes place and needs a broken symmetry. Finally, we show that tight confinement in a toroidal potential actually enhances soliton decay due to inhibition of soliton motion, but can lead to a periodic revival of the ring dark soliton after the first snake instability. DOI: 10.1103/PhysRevA.87.043601