Collapse and Bose-Einstein condensation in a trapped Bose-gas with negative scattering length

TL;DR

This paper investigates the dynamics of collapse and Bose-Einstein condensation in a trapped Bose gas with negative scattering length, highlighting the roles of particle flux and three-body recombination in the process.

Contribution

It provides a detailed analysis of the collapse process, showing how recombination and particle flux influence the condensate's evolution and prevent complete depletion.

Findings

Collapse occurs when the condensate reaches a critical atom number.

Recombination limits the collapse, leaving a finite condensate after each event.

The condensate undergoes oscillations and slow decay post-collapse.

Abstract

We find that the key features of the evolution and collapse of a trapped Bose condensate with negative scattering length are predetermined by the particle flux from the above-condensate cloud to the condensate and by 3-body recombination of Bose-condensed atoms. The collapse, starting once the number of Bose-condensed atoms reaches the critical value, ceases and turns to expansion when the density of the collapsing cloud becomes so high that the recombination losses dominate over attractive interparticle interaction. As a result, we obtain a sequence of collapses, each of them followed by dynamic oscillations of the condensate. In every collapse the 3-body recombination burns only a part of the condensate, and the number of Bose-condensed atoms always remains finite. However, it can comparatively slowly decrease after the collapse, due to the transfer of the condensate particles to the above-condensate cloud in the course of damping of the condensate oscillations.