Minimal model for active nematics: quasi-long-range order and giant fluctuations

TL;DR

This paper introduces a minimal microscopic model for active nematics, demonstrating a Kosterlitz-Thouless-like transition to quasi-long-range order and giant density fluctuations, aligning with theoretical predictions for non-equilibrium systems.

Contribution

It presents a simplified microscopic model for active nematics that captures key phase transition behaviors and fluctuation phenomena in two dimensions.

Findings

Exhibits a Kosterlitz-Thouless-like transition to quasi-long-range order.

Shows the presence of giant density fluctuations in the ordered phase.

Aligns with previous theoretical predictions for active nematic systems.

Abstract

We propose a minimal microscopic model for active nematic particles similar in spirit to the Vicsek model for self-propelled polar particles. In two dimensions, we show that this model exhibits a Kosterlitz-Thouless-like transition to quasi-long-range orientational order and that in this non-equilibrium context, the ordered phase is characterized by giant density fluctuations, in agreement with the predictions of Ramaswamy {\it et al.} [Europhys. Lett. {\bf 62}, 196 (2003)].