Active Ornstein-Uhlenbeck model for bacterial heat engines

Area of Science:

• Thermodynamics
• Statistical Mechanics
• Soft Matter Physics

Background:

• Bacterial heat engines offer a unique system for studying thermodynamics in biological contexts.
• Understanding the behavior of active matter is crucial for developing novel energy conversion devices.
• Colloidal probes in active baths provide a tractable experimental model for complex many-body systems.

Purpose of the Study:

• To investigate a cyclic bacterial heat engine model using Brownian dynamics simulations.
• To determine an effective model for analyzing the stochastic thermodynamics of such systems.
• To assess the applicability of the active Ornstein-Uhlenbeck particle (AOUP) model.

Main Methods:

• Brownian dynamics simulations of a harmonically confined colloidal probe particle.
• Modeling the bath with active Brownian particles.
• Analyzing probability densities for stochastic work, heat, and efficiency.

Main Results:

• For intermediate activities, active noise on large probes approximates Gaussian with exponential autocorrelation.
• Probability densities for work, heat, and efficiency are well-represented by the AOUP model.
• The AOUP model remains accurate even with nonexponential tails in the active noise autocorrelation.

Conclusions:

• The active Ornstein-Uhlenbeck particle (AOUP) serves as a convenient, accurate, and analytically tractable effective model for bacterial heat engines.
• This effective model simplifies the analysis of experimental bacterial heat engines, particularly with large probes and stiff traps.
• The AOUP model facilitates deeper insights into the stochastic thermodynamics of active matter systems.