Dynamics of condensation in the symmetric inclusion process

TL;DR

This paper rigorously analyzes the formation and dynamics of condensates in the symmetric inclusion process, revealing how multiple condensates coalesce into a single one through diffusive and jump processes.

Contribution

It provides the first rigorous characterization of condensate dynamics in the inclusion process, including coarsening behavior and limiting motion on various network structures.

Findings

Condensates emerge on the time scale 1/m_N for strong interactions.

Single condensate performs a random walk on the set S.

Multiple condensates coalesce into one through diffusive and jump processes.

Abstract

The inclusion process is a stochastic lattice gas, which is a natural bosonic counterpart of the well-studied exclusion process and has strong connections to models of heat conduction and applications in population genetics. Like the zero-range process, due to attractive interaction between the particles, the inclusion process can exhibit a condensation transition. In this paper we present first rigorous results on the dynamics of the condensate formation for this class of models. We study the symmetric inclusion process on a finite set $S$ with total number of particles $N$ in the regime of strong interaction, i.e. with independent diffusion rate $m=m_N \to 0$. For the case $N m_N\to\infty$ we show that on the time scale $1/m_N$ condensates emerge from general homogeneous initial conditions, and we precisely characterize their limiting dynamics. In the simplest case of two sites or a fully connected underlying random walk kernel, there is a single condensate hopping over $S$ as a continuous-time random walk. In the non fully connected case several condensates can coexist and exchange mass via intermediate sites in an interesting coarsening process, which consists of a mixture of a diffusive motion and a jump process, until a single condensate is formed. Our result is based on a general two-scale form of the generator, with a fast-scale neutral Wright-Fisher diffusion and a slow-scale deterministic motion. The motion of the condensates is described in terms of the generator of the deterministic motion and the harmonic projection corresponding to the absorbing states of the Wright-Fisher diffusion.