Heat Fluctuations in Chemically Active Systems

TL;DR

This paper develops a stochastic field theory to analyze heat fluctuations in chemically active systems, revealing that active fluctuations dominate thermal ones at large scales and identifying multiple crossover regimes.

Contribution

It introduces a novel Poisson noise-based framework to characterize active heat fluctuations across different scales in non-equilibrium systems.

Findings

Active fluctuations dominate at large scales

Multiple crossovers exist at intermediate scales

Local equilibrium holds at specific scales

Abstract

Chemically active systems such as living cells are maintained out of thermal equilibrium due to chemical events which generate heat and lead to active fluctuations. A key question is to understand on which time and length scales active fluctuations dominate thermal fluctuations. Here, we formulate a stochastic field theory with Poisson white noise to describe the heat fluctuations which are generated by stochastic chemical events and lead to active temperature fluctuations. We find that on large length and time scales, active fluctuations always dominate thermal fluctuations. However, at intermediate length and time scales, multiple crossovers exist which highlight the different characteristics of active and thermal fluctuations. Our work provides a framework to characterize fluctuations in active systems and reveals that local equilibrium holds at certain length and time scales.