# Effective Entropy Production and Thermodynamic Uncertainty Relation of Active Brownian Particles

## TL;DR

This paper develops a coarse-grained thermodynamic framework for active Brownian particles, introducing effective entropy production and thermodynamic uncertainty relations to better understand their irreversibility and phase separation phenomena.

## Contribution

It introduces a new coarse-grained Fokker-Planck approach to define effective entropy production in active matter systems, linking it to phase separation and thermodynamic bounds.

## Key findings

- Effective entropy production quantifies irreversibility in active particles.
- The framework captures interface and defect phenomena in motility-induced phase separation.
- Derived entropic bounds and TUR for generalized currents in active matter.

## Abstract

Understanding stochastic thermodynamics of active Brownian particles (ABPs) system has been an important topic in very recent years. In this article we study a general model of active Brownian particle systems by introducing a coarse-grained Fokker-Planck equation, which allows us to identify an effective entropy production along a stochastic trajectory, wherein an activity and configuration dependent diffusion coefficient comes into play with an important role. Although the hidden component between the true entropy production and the effective one is dominant, the effective entropy production still act as a reliable measure to quantify the dynamical irreversibility, capturing important phenomenon such as the interface and defects of motility induced phase separation (MIPS). Furthermore, in this framework, we are able to obtain the entropic bound as well as TUR associated with any generalized currents in the systems. We expect the new conceptual quantities proposed here to be broadly used in the context of active matter.