Observation of subdiffusion of a disordered interacting system

E. Lucioni, B. Deissler, L. Tanzi, G. Roati, M. Modugno, M. Zaccanti, M. Larcher, F. Dalfovo, M. Inguscio, G. Modugno

Published 2010-11-10, updated 2011-05-19Version 2

We study the transport dynamics of matter-waves in the presence of disorder and nonlinearity. An atomic Bose-Einstein condensate that is localized in a quasiperiodic lattice in the absence of atom-atom interaction shows instead a slow expansion with a subdiffusive behavior when a controlled repulsive interaction is added. The measured features of the subdiffusion are compared to numerical simulations and a heuristic model. The observations confirm the nature of subdiffusion as interaction-assisted hopping between localized states and highlight a role of the spatial correlation of the disorder.