Stochastic thermodynamics, fluctuation theorems, and molecular machines

TL;DR

This paper reviews stochastic thermodynamics, detailing how it extends classical thermodynamics to small systems and non-equilibrium processes, with applications to molecular machines, fluctuation theorems, and efficiency analysis.

Contribution

It unifies fluctuation theorems and thermodynamic principles for small systems, providing a comprehensive framework for analyzing non-equilibrium stochastic processes and molecular machines.

Findings

Derivation of unified fluctuation theorems from a master theorem

Application of fluctuation theorems to molecular motors and thermoelectric devices

Systematic analysis of efficiency at maximum power beyond linear response

Abstract

Stochastic thermodynamics as reviewed here systematically provides a framework for extending the notions of classical thermodynamics like work, heat and entropy production to the level of individual trajectories of well-defined non-equilibrium ensembles. It applies whenever a non-equilibrium process is still coupled to one (or several) heat bath(s) of constant temperature. Paradigmatic systems are single colloidal particles in time-dependent laser traps, polymers in external flow, enzymes and molecular motors in single molecule assays, small biochemical networks and thermoelectric devices involving single electron transport. For such systems, a first-law like energy balance can be identified along fluctuating trajectories. Various integral and detailed fluctuation theorems, which are derived here in a unifying approach from one master theorem, constrain the probability distributions for work, heat and entropy production depending on the nature of the system and the choice of non-equilibrium conditions. For non-equilibrium steady states, particularly strong results hold like a generalized fluctuation-dissipation theorem involving entropy production. Ramifications and applications of these concepts include optimal driving between specified states in finite time, the role of measurement-based feedback processes and the relation between dissipation and irreversibility. Efficiency and, in particular, efficiency at maximum power, can be discussed systematically beyond the linear response regime for two classes of molecular machines, isothermal ones like molecular motors, and heat engines like thermoelectric devices, using a common framework based on a cycle decomposition of entropy production.