Topological structure and dynamics of three dimensional active nematics

TL;DR

This paper explores the structure and dynamics of three-dimensional active nematics, revealing complex defect behaviors and turbulent-like flows driven by active stresses, expanding understanding beyond two-dimensional systems.

Contribution

It introduces the creation and detailed analysis of 3D active nematics, highlighting the role of disclination loops and their dynamics, a novel extension from 2D to 3D systems.

Findings

Disclination loops are the dominant excitations in 3D active nematics.

Active stresses induce turbulent-like chaotic flows.

Defect dynamics involve complex recombination events.

Abstract

Point-like motile topological defects control the universal dynamics of diverse two-dimensional active nematics ranging from shaken granular rods to cellular monolayers. A comparable understanding in higher dimensions has yet to emerge. We report the creation of three-dimensional active nematics by dispersing extensile microtubule bundles in a passive colloidal liquid crystal. Light-sheet microscopy reveals the millimeter-scale structure of active nematics with a single bundle resolution and the temporal evolution of the associated nematic director field. The dominant excitations of three-dimensional active nematics are extended charge-neutral disclination loops that undergo complex dynamics and recombination events. These studies introduce a new class of non-equilibrium systems whose turbulent-like dynamics arises from the interplay between internally generated active stresses, the chaotic flows and the topological structure of the constituent defects.