Motion of dark solitons in a non-uniform flow of Bose-Einstein condensate

TL;DR

This paper investigates the dynamics of dark solitons in a non-uniform Bose-Einstein condensate flow using Hamiltonian mechanics, deriving equations of motion and confirming results through numerical simulations.

Contribution

It introduces a Hamiltonian framework for describing dark soliton motion in non-uniform condensates, accounting for counterflow effects and deriving Newton-like equations.

Findings

Derived Hamiltonian equations for soliton dynamics.

Confirmed analytical results with numerical simulations.

Identified effects of counterflow on soliton motion.

Abstract

We study motion of dark solitons in a non-uniform one-dimensional flow of Bose-Einstein condensate. Our approach is based on Hamiltonian mechanics applied to the particle-like behavior of dark solitons in a slightly non-uniform and slowly changing surrounding. In one-dimensional geometry, the condensate's wave function undergoes the jump-like behavior across the soliton and this leads to generation of the counterflow in the background condensate. For correct description of soliton's dynamics, the contributions of this counterflow to the momentum and energy of the soliton are taken into account. The resulting Hamilton equations are reduced to the Newton-like equation for the soliton's path and this Newton equation is solved in several typical situations. The analytical results are confirmed by numerical calculations.