From short-time diffusive to long-time ballistic dynamics: The unusual center-of-mass motion of quantum bright solitons.

Brownian motion is ballistic on short time scales and diffusive on long time scales. Our theoretical investigations indicate that one can observe the exact opposite--an "anomalous diffusion process" where initially diffusive motion becomes ballistic on longer time scales--in an ultracold atomic system with a size comparable to macromolecules. This system is the center-of-mass motion of a quantum matter-wave bright soliton for which the dominant source of decoherence is three-particle losses. Our simulations show that such unusual center-of-mass dynamics should be observable on experimentally accessible time scales. [ABSTRACT FROM AUTHOR]