Dark soliton past a finite-size obstacle

TL;DR

This paper models the interaction of a dark soliton with a finite obstacle in a Bose condensate, revealing classical particle-like behavior, radiation emission, and conditions for quenching radiation at sound speed.

Contribution

It introduces a classical particle model for dark soliton dynamics with an obstacle, including radiative effects and radiation suppression at sound speed.

Findings

Soliton behaves as a particle with twice the mass of a bare particle.

Radiation emitted during collision forms two counterpropagating wave packets.

Radiation is quenched when soliton velocity reaches the speed of sound.

Abstract

We consider the collision of a dark soliton with an obstacle in a quasi-one-dimensional Bose condensate. We show that in many respects the soliton behaves as an effective classical particle of mass twice the mass of a bare particle, evolving in an effective potential which is a convolution of the actual potential describing the obstacle. Radiative effects beyond this approximation are also taken into account. The emitted waves are shown to form two counterpropagating wave packets, both moving at the speed of sound. We determine, at leading order, the total amount of radiation emitted during the collision and compute the acceleration of the soliton due to the collisional process. It is found that the radiative process is quenched when the velocity of the soliton reaches the velocity of sound in the system.