Creation of solitons and vortices by Bragg reflection of Bose-Einstein condensates in an optical lattice

TL;DR

This paper investigates how Bose-Einstein condensates in optical lattices form solitons and vortices through Bragg reflection, revealing density-dependent dynamics and instabilities leading to explosive expansion.

Contribution

It demonstrates the formation of solitons and vortices via Bragg reflection in BECs and explores the effects of atom density on these phenomena and condensate stability.

Findings

High atom densities lead to soliton and vortex trains after first Bragg reflection.

Lower densities require multiple reflections for soliton and vortex formation.

Bragg reflection can destabilize the condensate and cause explosive expansion.

Abstract

We study the dynamics of Bose-Einstein condensates in an optical lattice and harmonic trap. The condensates are set in motion by displacing the trap and initially follow simple semiclassical paths, shaped by the lowest energy band. Above a critical displacement, the condensate undergoes Bragg reflection. For high atom densities, the first Bragg reflection generates a train of solitons and vortices, which destabilize the condensate and trigger explosive expansion. At lower densities, soliton and vortex formation requires multiple Bragg reflections, and damps the center-of-mass motion.