Modeling the Efficiency and Effective Temperature of Bacterial Heat Engines

TL;DR

This paper uses simulations to model bacterial heat engines, demonstrating how their efficiency can be understood through effective temperature concepts and aligning with experimental results.

Contribution

It introduces a Brownian dynamics simulation framework for bacterial Stirling engines, linking active particle models to thermodynamic performance.

Findings

Quantitative reproduction of experimental efficiencies

Validation of effective temperature as a key parameter

Agreement with the second law of thermodynamics

Abstract

We present a Brownian dynamics simulation of the bacterial Stirling engine studied by Krishnamurthy et al., Nat. Phys. 12, 1134 (2016). In their experimental setup, an overdamped colloid in an optical trap with time-modulated stiffness interacts with a bacterial bath that we represent by an ensemble of overdamped active particles. In the parameter regime of the experiment the thermodynamic performance is governed by an effective temperature and can be parametrized analytically by active Brownian particle models. We quantitatively reproduce the efficiencies reported for the experiments under the assumption that energy exchange with the bath during isochores of the cycle is entirely recuperated and in agreement with the second law.