Out-of-equilibrium interacting Bose gases in disorder

TKM Institutsseminar


Thibault Scoquart


08/04/2021 14:00




Laboratoire Kastler Brossel, Paris


Igor Gornyi


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].
J. Billy, V. Josse, Z. Zuo et al. Nature 453, 891–894 (2008)
I. Manai, J-F. Clément et al. Phys. Rev. Lett. 115, 240603
T. Scoquart, T. Wellens, N. Cherroret and D. Delande, Phys. Rev. Research 2, 033349 (2020)
T. Scoquart, N. Cherroret et al. EPL 132, 66001 (2020)