Dresden 2011 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 27: ISS Transport and Localization of Interacting Bosons I
DY 27.3: Vortrag
Mittwoch, 16. März 2011, 17:00–17:15, HSZ 02
Observation of subdiffusion of a disordered interacting system — •Eleonora Lucioni1, Benjamin Deissler1, Luca Tanzi1, Chiara D’Errico1, Giacomo Roati1, Matteo Zaccanti1,2, Michele Modugno1,3, Massimo Inguscio1, and Giovanni Modugno1 — 1LENS and Università di Firenze, and CNR-INO, Italy — 2Institut für Quantenoptik und Quanteninformation, Innsbruck, Austria — 3IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
We study the transport dynamics of matter-waves in the presence of disorder and non-linearity. A Bose-Einstein Condensate of 39K atoms is let free to expand in a quasiperiodic lattice realized by superimposing two laser beams of incommensurate wavelength in standing wave configuration. By means of a broad magnetic Feshbach resonance it is possible to tune the scattering length between atoms at will. In the noninteracting case this system is an experimental realization of the Aubry-André model: if the disorder is strong enough, the system is localized and no expansion is permitted (Anderson localization).
The presence of a weak repulsive interaction allows the coupling between orthogonal localized single particle states and destroys localization. In this case we observe a change of shape of the atomic cloud during the expansion and a slow increase of the width σ of the sample that follows a subdiffusive law: σ(t)∝ tα, with α=0.2−0.4. We find that the exponent increases with the initial interaction energy and the localization length.