How Quorum Sensing Shapes Clustering in Active Matter

TL;DR

This paper investigates how quorum sensing influences clustering in active matter, revealing non-monotonic behaviors, transient states, and effective bistability, with implications for understanding collective phenomena in biological and synthetic systems.

Contribution

It introduces a kinetic theory and simulations showing how quorum sensing causes complex clustering behaviors, including reentrant phases and bistability, in active matter systems.

Findings

Clustering exhibits a non-monotonic dependence on quorum-sensing strength.

Long-lived transient states retain initial condition memory.

Quorum sensing induces effective cluster bistability.

Abstract

Self-propelled particles undergoing persistent motion can accumulate either through excluded-volume interactions or through quorum sensing, where self-propulsion decreases at high local density. Using kinetic balance theory and simulations, we show that the interplay of these two mechanisms produces a reentrant, non-monotonic behavior in which clustering passes through a pronounced minimum as quorum-sensing strength or persistence time varies. Beyond a threshold quorum-sensing strength, we find long-lived transient states that retain memory of initial conditions, including kinetically arrested active gels. Although quorum sensing can mimic attractive interactions, it also acts strongly in dilute regions, producing an effective cluster bistability that is captured by our theory. Our results explain collective states observed experimentally in synthetic and biological active systems.