Fluctuations in 2D fire-ant collectives

Abstract

Active matter resides far from equilibrium since its constituents are constantly dissipating energy by converting ambient or internal energy into work. Previous studies showed that active matter exhibit giant number fluctuations(GNF). By studying fire-ant systems, we find that in the course of time, ants exhibit two distinctive phases: ’active’, where essentially all ants move, and ’inactive’, where a large fraction of ants are stationary. In both states, we find giant number fluctuations. However, the underlying origin for this result is different. In the ’active’ case, the results are genuinely the same resulting in GNF like in other active matter systems. In the ’inactive’ case, the GNF we see are due to the inhomogeneous nature of the system in this phase