Abstract

For the last few decades, the use of cold atomic gases in well-controlled optical potentials have boosted
our understanding of the interplay between disorder and interactions in quantum systems, in particular
in the context of Anderson localization [1] and its many-body counterpart [2]. In this context, special
attention has been devoted to the out-of-equilibrium dynamics of quantum gases, after a disorder and/or
an interaction quench.
In this talk, I will review my theoretical work on the out-of-equilibrium dynamics of weakly inter-
acting Bose gases after they are sent with finite velocity in a disordered potential. Without interactions,
well-known mesoscopic phenomena emerge in momentum space from coherent multiple scattering : a back-
ground of diffusive particles, and a coherent backscattering peak (CBS, a direct consequence of weak lo-
calization). In the presence of weak particle interactions, we find that CBS gets destroyed according to a
dephasing-like mechanism [3]. Both the diffusive and coherent components of the gas evolve toward ther-
malization, which can be described by coupled kinetic equations that we derive using a quantum transport
theory. As interactions become stronger, particle scattering on the disorder become less and less relevant,
and the dynamics of the gas resembles that of a superfluid. In the superfluid regime, the gas is driven
towards a pre-thermal state and exhibits algebraic correlations that spread within a light cone [4].
[1]
J. Billy, V. Josse, Z. Zuo et al. Nature 453, 891–894 (2008)
[2]
I. Manai, J-F. Clément et al. Phys. Rev. Lett. 115, 240603
[3]
T. Scoquart, T. Wellens, N. Cherroret and D. Delande, Phys. Rev. Research 2, 033349 (2020)
[4]
T. Scoquart, N. Cherroret et al. EPL 132, 66001 (2020)