Nonlinear scattering of atomic bright solitons in disorder (Vol. 48, No. 3)

Histogram of the atom reflected fraction when a soliton is scattered in a disordered potential. The atoms tend to be collectively either transmitted or reflected in contrast to the observation for non-interacting atoms. The non-linear scattering behaviour appears as a double peak structure in the histogram

Atomic bright solitons are self-trapping Bose-Einstein condensates. They exist in one-dimension because of attractive interactions. We observe nonlinear scattering of 39K atomic bright solitons launched in a one-dimensional disordered potential. The atoms from solitons behave collectively, i.e. are either mostly reflected or transmitted in contrast to non interacting atoms, which behave as independent quantum particles. This is the first observation of a non-linear behaviour with atomic bright solitons beyond their self-trapped nature. It requires the soliton interaction energy to be of the order of its center-of-mass kinetic energy. Our observations are reproduced in a mean-field framework by Gross-Pitaevskii simulations, while mesoscopic quantum superpositions of the soliton being fully reflected and fully transmitted are not expected for our parameters. We discuss the conditions for observing such superpositions, which would find applications in atom interferometry beyond the standard quantum limit.

A. Boissé, G. Berthet, L. Fouché, G. Salomon, A. Aspect, S. Lepoutre and T. Bourdel, Nonlinear scattering of atomic bright solitons in disorder, EPL 117, 10007 (2017)