Mean field effects on the scattered atoms in condensate collisions

TL;DR

This paper investigates the effects of mean field interactions on scattered atoms during Bose-Einstein condensate collisions, highlighting the limitations of simplified models and emphasizing the importance of including mean field dynamics for accurate predictions.

Contribution

It demonstrates that incorporating the evolving mean field and on-condensate pair creation improves the accuracy of theoretical descriptions of condensate collisions.

Findings

Reduced Bogoliubov description often inaccurate in experimental regimes.

Mean field effects significantly influence the scattered atom halo.

Including mean field dynamics can reconcile theory with experiments.

Abstract

We consider the collision of two Bose Einstein condensates at supersonic velocities and focus on the halo of scattered atoms. This halo is the most important feature for experiments and is also an excellent testing ground for various theoretical approaches. In particular we find that the typical reduced Bogoliubov description, commonly used, is often not accurate in the region of parameters where experiments are performed. Surprisingly, besides the halo pair creation terms, one should take into account the evolving mean field of the remaining condensate and on-condensate pair creation. We present examples where the difference is clearly seen, and where the reduced description still holds.