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Abstract

Solitons are fascinating non-dispersive solutions to non-linear systems, which appear in various scenarios across nature. Because of their stability and longevity these excitations are of great interest in non-equilibrium scenarios. In multi-component systems, the solitons acquire an internal degree of freedom, contributing to a rich variety of interaction effects, which make these excitations particularly interesting.

In this work we experimentally realize the deterministic generation of coherent three-component vector solitons in a quasi one-dimensional Bose-Einstein condensate of 87Rb. For this, a local spin rotation is generated with a single laser beam. We investigate the spatial profiles and propagation of the solitons in a trap as well as their dynamics during soliton-soliton collisions. These are found to be well-described by the analytical Manakov model. In particular, we realize the striking phenomenon of ploarization scattering during soliton collisions, known from the attractive multi-component Manakov system, in a repulsively interacting condensate. The polarization dynamics of the vector solitons is further applied in an application to precisely determine magnetic field gradients.

In a second set of experiments, the non-equilibrium dynamics following an interaction quench is investigated. For this, the excitations in the transverse spin which are spontaneously generated by spin-changing collisions are characterized. Utilizing multiple solitons as initial condition, two regimes are realized, in which localized excitations either decay or strong fluctuations persist over long times. In these scenarios, two distinct dynamical scaling evolutions are identified. These indicate the presence of two different non-thermal fixed points in the spin-1 Bose gas.