Breaking the resilience of a two-dimensional Bose-Einstein condensate to fragmentation

TL;DR

This paper investigates the dynamical fragmentation of a two-dimensional Bose-Einstein condensate during splitting, revealing that even a condensed ground state can evolve into a fragmented state due to low-lying excited states.

Contribution

It provides the first demonstration of dynamical fragmentation in a 2D BEC during splitting, highlighting the role of low-lying excited states in its dynamics.

Findings

Ground state remains condensed over a wide parameter range

Splitting process induces substantial fragmentation

Low-lying excited states influence BEC dynamics

Abstract

A two-dimensional Bose-Einstein condensate (BEC) split by a radial potential barrier is investigated. We determine on an accurate many-body level the system's ground-state phase diagram as well as a time-dependent phase diagram of the splitting process. Whereas the ground state is condensed for a wide range of parameters, the time-dependent splitting process leads to substantial fragmentation. We demonstrate for the first time the dynamical fragmentation of a BEC despite its ground state being condensed. The results are analyzed by a mean-field model and suggest that a large manifold of low-lying fragmented excited states can significantly impact the dynamics of trapped two-dimensional BECs.