We theoretically study the propagation of an interacting Bose-Einstein condensate in a two-dimensional disorder potential, following the principle of an atom laser. The constructive interference between time-reversed scattering paths gives rise to coherent backscattering, which may be observed under the form of a sharp cone in the disorder-averaged angular backscattered current. As is found by the numerical integration of the Gross-Pitaevskii equation, this coherent backscattering cone is inversed when a nonvanishing interaction strength is present, indicating a crossover from constructive to destructive interferences. Numerical simulations based on the truncated Wigner method allow one to go beyond the mean-field approach and show that dephasing renders this signature of antilocalization hidden behind a structureless and dominant incoherent contribution as the interaction strength is increased and the injected density decreased, in a regime of parameters far away from the mean-field limit. However, despite a partial dephasing, we observe that this weak antilocalization scenario prevails for finite interaction strengths, opening the way for an experimental observation with ${}^{87}\mathrm{Rb}$ atoms.

• Received 22 December 2020
• Accepted 25 February 2021

DOI:https://doi.org/10.1103/PhysRevA.103.033319