Bose-Einstein condensate in a quasiperiodic optical lattice:
A quantum gas at the edge between order and disorder

Laurent Sanchez-Palencia

Institut für Theoretische Physik, Universität Hannover, Appelstrasse, 2, D-30167 Hannover, Germany

We study theoretically the behavior of a Bose-Einstein condensate trapped in an optical quasicrystal (quasi-periodic optical lattice). This offers an intriguing intermediate situation at the edge between ordered and disordered systems. We analyse i) the time-of-flight interference pattern of the condensate released from the optical quasicrystal, and ii) the localization effects during the expansion of the condensate inside the optical quasicrystal. We investigate in detail the crossover between diffusive and localized regimes when the quasi-periodic potential is switched on. Finaly, we study the role of the interatomic interactions in the condensate diffusion.