Structure formation during the collapse of a dipolar atomic Bose-Einstein condensate

TL;DR

This paper explores the collapse dynamics of dipolar Bose-Einstein condensates using numerical simulations, revealing regimes of global and local collapse influenced by interactions and trap geometry, with implications for experimental observations.

Contribution

It introduces the application of Thomas-Fermi hydrodynamic equations to study collapse and distinguishes between global and local collapse regimes in dipolar BECs.

Findings

Global collapse leads to elongated or flattened states.

Local collapse results in density shells, disks, or stripes.

Collapse behavior depends on dipolar interactions and trap geometry.

Abstract

We investigate the collapse of a trapped dipolar Bose-Einstein condensate. This is performed by numerical simulations of the Gross-Pitaevskii equation and the novel application of the Thomas-Fermi hydrodynamic equations to collapse. We observe regimes of both global collapse, where the system evolves to a highly elongated or flattened state depending on the sign of the dipolar interaction, and local collapse, which arises due to dynamically unstable phonon modes and leads to a periodic arrangement of density shells, disks or stripes. In the adiabatic regime, where ground states are followed, collapse can occur globally or locally, while in the non-adiabatic regime, where collapse is initiated suddenly, local collapse commonly occurs. We analyse the dependence on the dipolar interactions and trap geometry, the length and time scales for collapse, and relate our findings to recent experiments.