Dark-Bright Soliton Dynamics Beyond the Mean-Field Approximation

TL;DR

This paper investigates the complex dynamics of dark-bright solitons beyond mean-field theory, revealing fragmentation, entanglement, and novel soliton behaviors not predicted by traditional models.

Contribution

It introduces a beyond mean-field approach to dark-bright soliton dynamics, highlighting fragmentation, entanglement, and the splitting of solitons into daughter waves.

Findings

Fragmentation significantly affects soliton dynamics.

Presence of bipartite entanglement between species.

Splitting of solitons into fast and slow daughter waves.

Abstract

The dynamics of dark-bright solitons beyond the mean-field approximation is investigated. We first examine the case of a single dark-bright soliton and its oscillations within a parabolic trap. Subsequently, we move to the setting of collisions, comparing the mean-field approximation to that involving multiple orbitals in both the dark and the bright component. Fragmentation is present and significantly affects the dynamics, especially in the case of slower solitons and in that of lower atom numbers. It is shown that the presence of fragmentation allows for bipartite entanglement between the distinguishable species. Most importantly the interplay between fragmentation and entanglement leads to the splitting of each of the parent mean-field dark-bright solitons, placed off-center within the parabolic trap, into a fast and a slow daughter solitary wave. The latter process is in direct contrast to the predictions of the mean-field approximation. A variety of excitations including dark-bright solitons in multiple (concurrently populated) orbitals is observed. Dark-antidark states and domain-wall-bright soliton complexes can also be observed to arise spontaneously in the beyond mean-field dynamics.