Dark soliton dynamics in Bose-Einstein condensates at finite temperature

The dynamics of a dark soliton in an elongated Bose-Einstein condensate at finite temperatures is studied using numerical simulations. We find that in the presence of harmonic confinement the soliton may oscillate even at finite temperatures, but with an amplitude that increases with time, indicating the decay of the soliton. The timescale of this decay decreases both with increasing temperature and with increasing initial soliton velocity. Simulations performed for the experiment of S. Burger et al., Phys. Rev. Lett. 83, 5198 (1999), reveal excellent agreement with the observed soliton decay, confirming the crucial role of the thermal cloud in soliton dynamics.