Sticking Transition in a Minimal Model for the Collisions of Active Particles in Quantum Fluids

TL;DR

This paper introduces a minimal coupled model of particles and superfluid dynamics to study collision behaviors, revealing a transition from elastic to sticking collisions and the resulting aggregation phenomena.

Contribution

It presents a novel coupled model combining particle motion with the Gross-Pitaevskii equation to analyze collision outcomes in superfluid systems.

Findings

Identifies a superfluid-mediated attractive interaction between particles.

Demonstrates a transition from elastic to inelastic collisions as parameters vary.

Shows that sticking collisions lead to particle aggregation and clustering.

Abstract

Particles of low velocity, travelling without dissipation in a superfluid, can interact and emit sound when they collide. We propose a minimal model in which the equations of motion of the particles, including a short-range repulsive force, are self-consistently coupled with the Gross-Pitaevskii equation. We use this model to demonstrate the existence of an effective superfluid-mediated attractive interaction between the particles; and we study numerically the collisional dynamics of particles as a function of their incident kinetic energy and the length-scale of the repulsive force. We find a transition from almost elastic to completely inelastic (sticking) collisions as the parameters are tuned. We find that aggregation and clustering result from this sticking transition in multi-particle systems.