Formation of fundamental structures in Bose-Einstein Condensates

TL;DR

This paper explores how nonlinear interactions in Bose-Einstein Condensates modeled by the Gross Pitaevskii equation can lead to the formation of stable structures like gray solitons, especially during condensate collisions.

Contribution

It provides an analysis of soliton formation conditions in Bose-Einstein Condensates, including an analytic expression for when solitons emerge from interference fringes.

Findings

Gray solitons can form from dark interference fringes.

Soliton formation depends on energy considerations.

Analytic condition for soliton emergence is derived.

Abstract

The meanfield interaction in a Bose condensate provides a nonlinearity which can allow stable structures to exist in the meanfield wavefunction. We discuss a number of examples where condensates, modelled by the one dimensional Gross Pitaevskii equation, can produce gray solitons and we consider in detail the case of two identical condensates colliding in a harmonic trap. Solitons are shown to form from dark interference fringes when the soliton structure, constrained in a defined manner, has lower energy than the interference fringe and an analytic expression is given for this condition.