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Dr. Pierre Lugan

Ecole Polytechnique Fédérale de Lausanne (EPFL)

Tuesday, May 28th, 2013 at 12:00:00 PM  

Conference room Querzoli - LENS - via Nello Carrara 1 - Sesto Fiorentino (Florence)

Published on-line at 01:12:11 PM on Friday, May 24th, 2013

Coherence properties of weakly interacting Bose gases across the superfluid-Bose-glass transition

Coherence properties of weakly interacting bosons in one and two dimensions in the presence of disorder.

Due to the high degree of control they offer, ultracold atomic gases have emerged as a powerful tool to explore the physics of disordered quantum systems. While pioneering experiments focused on the observation of Anderson localization in a regime of negligible interactions, more recent ones turned to a systematic investigation of the effects of disorder in interacting systems (10.1103/PhysRevLett.98.130404, 10.1088/1367-2630/13/2/023020, 10.1103/PhysRevA.85.033602). In Bose systems, disorder may destroy superfluidity even at zero temperature and trigger a phase transition to a gapless compressible insulator called Bose glass. To date, some aspects of this transition are not fully understood, even in the one-dimensional geometry (arXiv:1302.3423).

We examine here the coherence properties of weakly interacting bosons in one and two dimensions in the presence of disorder. The asymptotic behavior of the one-body density matrix which characterizes (quasi-)long-range order is analyzed numerically within the framework of an extended Bogoliubov theory that describes correctly the high-density mean-field limit. We used our approach to delineate the zero-temperature phase diagram in 1D and study the disorder-induced condensate depletion in 2D (10.1088/1367-2630/15/4/045006). I will also touch on open issues regarding the description of the Bose-glass transition within mean-field theory.

For further informations, please contact Dr. Augusto Smerzi.