Spontaneous soliton formation and modulational instability in Bose-Einstein condensates

TL;DR

This paper investigates how density fringes from self-interference in elongated attractive Bose-Einstein condensates lead to modulational instability and soliton formation, revealing unique features and collapse phenomena.

Contribution

It demonstrates the role of self-interference in seedling modulational instability and explores collapse dynamics in matter-wave soliton trains.

Findings

Density fringes seed modulational instability

Novel features differ from homogeneous cases

Collapse processes produce bursts of hot atoms

Abstract

The dynamics of an elongated attractive Bose-Einstein condensate in an axisymmetric harmonic trap is studied. It is shown that density fringes caused by self-interference of the condensate order parameter seed modulational instability. The latter has novel features in contradistinction to the usual homogeneous case known from nonlinear fiber optics. Several open questions in the interpretation of the recent creation of the first matter-wave bright soliton train [Strecker {\it et al.} Nature {\bf 417} 150 (2002)] are addressed. It is shown that primary transverse collapse, followed by secondary collapse induced by soliton--soliton interactions, produce bursts of hot atoms at different time scales.