Collective Motion of Vibrated Polar Disks

TL;DR

This paper experimentally investigates how vibrated polar disks exhibit collective motion and giant number fluctuations, revealing the conditions for large-scale alignment and validating theoretical predictions about fluctuation scaling.

Contribution

It demonstrates the emergence of collective motion in vibrated polar disks and confirms the theoretical scaling of giant number fluctuations in such active matter systems.

Findings

Large-scale collective motion observed at specific vibration amplitudes

Giant number fluctuations with predicted scaling exponent

Alignment during collisions due to self-propulsion and repulsion

Abstract

We experimentally study a monolayer of vibrated disks with a built-in polar asymmetry which enables them to move quasi-balistically on a large persistence length. Alignment occurs during collisions as a result of self-propulsion and hard core repulsion. Varying the amplitude of the vibration, we observe the onset of large-scale collective motion and the existence of giant number fluctuations with a scaling exponent in agreement with the predicted theoretical value.