Abstract
We theoretically study the out-of-equilibrium dynamics in momentum space of a weakly interacting disordered Bose gas launched with a finite velocity. In the absence of interactions, coherent multiple scattering gives rise to a background of diffusive particles, on top of which a coherent backscattering interference emerges. We revisit this scenario in the presence of interactions, using a diagrammatic quantum transport theory. We find that the dynamics is governed by coupled kinetic equations describing the thermalization of the diffusive and coherent components of the gas. This phenomenon leads to a destruction of coherent backscattering, well described by an exponential relaxation whose rate is controlled by the particle collision time. These predictions are confirmed by numerical simulations.
Highlights
When perturbed from an equilibrium situation, isolated many-body systems generally experience a thermalization process and eventually return to equilibrium at sufficiently long time [1]
coherent backscattering (CBS) of cold atoms, in particular, was probed in an opticslike configuration where an ultracold Bose gas was initially given a finite mean velocity, and its subsequent dynamics in the presence of disorder probed in momentum space
Following [27,28,30,31], we consider the out-ofequilibrium dynamics of a two-dimensional, weakly interacting Bose gas initially prepared in a plane-wave state with finite velocity in a random potential
Summary
When perturbed from an equilibrium situation, isolated many-body systems generally experience a thermalization process and eventually return to equilibrium at sufficiently long time [1]. CBS of cold atoms, in particular, was probed in an opticslike configuration where an ultracold Bose gas was initially given a finite mean velocity, and its subsequent dynamics in the presence of disorder probed in momentum space This configuration, originally introduced in [31], turned out to be useful to explore other interference phenomena such as coherent forward scattering [32], to achieve an echo spectroscopy of coherent transport in disorder [30,33], or to monitor the thermalization and dynamical formation of condensates in momentum space [34]. Following [27,28,30,31], we consider the out-ofequilibrium dynamics of a two-dimensional, weakly interacting Bose gas initially prepared in a plane-wave state with finite velocity in a random potential In this configuration, the momentum distribution quickly acquires a ring-shaped profile associated with classical particle diffusion, with an interference, CBS peak emerging on the top.
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