The geometry of thermodynamic control

TL;DR

This paper explores the Riemannian geometric structure of thermodynamic control, deriving optimal protocols for minimal dissipation in a particle in a harmonic potential, and validates these protocols numerically.

Contribution

It introduces a geometric framework for thermodynamic control protocols and derives explicit minimal-dissipation solutions for a specific model, connecting geometry with thermodynamic optimization.

Findings

Optimal control protocols are geodesics on a Riemannian manifold.

The friction tensor naturally emerges from a first-order derivative expansion.

Numerical tests confirm the geometric approach's validity.

Abstract

A deeper understanding of nonequilibrium phenomena is needed to reveal the principles governing natural and synthetic molecular machines. Recent work has shown that when a thermodynamic system is driven from equilibrium then, in the linear response regime, the space of controllable parameters has a Riemannian geometry induced by a generalized friction tensor. We exploit this geometric insight to construct closed-form expressions for minimal-dissipation protocols for a particle diffusing in a one dimensional harmonic potential, where the spring constant, inverse temperature, and trap location are adjusted simultaneously. These optimal protocols are geodesics on the Riemannian manifold, and reveal that this simple model has a surprisingly rich geometry. We test these optimal protocols via a numerical implementation of the Fokker-Planck equation and demonstrate that the friction tensor arises naturally from a first order expansion in temporal derivatives of the control parameters, without appealing directly to linear response theory.