Growth and Collapse of a Bose Condensate with Attractive Interactions

TL;DR

This paper studies the dynamics of a Bose-Einstein condensate of lithium-7 atoms with attractive interactions, focusing on collapse phenomena and nonequilibrium kinetics during cooling.

Contribution

It provides a detailed analysis of collapse dynamics and nonequilibrium behavior in an attractive Bose condensate, including multiple growth-collapse cycles.

Findings

Condensate becomes unstable near maximum atom number

Collapse dynamics can be quantitatively modeled

Multiple growth and collapse cycles occur before reaching stationarity

Abstract

We consider the dynamics of a quantum degenerate trapped gas of Li-7 atoms. Because the atoms have a negative s-wave scattering length, a Bose condensate of Li-7 becomes mechanically unstable when the number of condensate atoms approaches a maximum value. We calculate the dynamics of the collapse that occurs when the unstable point is reached. In addition, we use the quantum Boltzmann equation to investigate the nonequilibrium kinetics of the atomic distribution during and after evaporative cooling. The condensate is found to undergo many cycles of growth and collapse before a stationary state is reached.