Particle-Hole Asymmetry and Brightening of Solitons in A Strongly Repulsive BEC

TL;DR

This paper investigates solitary wave behavior in a strongly repulsive Bose-Einstein condensate, revealing particle-hole asymmetry and a novel brightening soliton that persists at high velocities, differing from traditional GPE solitons.

Contribution

It introduces a new soliton type in strongly interacting BECs and derives a modified evolution equation distinct from the Gross-Pitaevskii equation.

Findings

Discovery of a brightening soliton that persists up to sound velocity

Identification of particle-hole asymmetry in soliton dynamics

Characterization of soliton dispersion via Lieb II modes

Abstract

We study solitary wave propagation in the condensate of a system of hard-core bosons with nearest-neighbor interactions. For this strongly repulsive system, the evolution equation for the condensate order parameter of the system, obtained using spin coherent state averages is different from the usual Gross-Pitaevskii equation (GPE). The system is found to support two kinds of solitons when there is a particle-hole imbalance: a dark soliton that dies out as the velocity approaches the sound velocity, and a new type of soliton which brightens and persists all the way up to the sound velocity, transforming into a periodic wave train at supersonic speed. Analogous to the GPE soliton, the energy-momentum dispersion for both solitons is characterized by Lieb II modes.