Quantifying nonequlibrium thermodynamic operations in a multiterminal mesoscopic system

TL;DR

This paper analyzes a multiterminal mesoscopic system in the quantum Hall regime, introducing free-energy efficiencies to properly evaluate nonequilibrium thermodynamic operations and optimizing their performance.

Contribution

It defines and applies free-energy efficiencies for nonequilibrium resources, ensuring thermodynamic consistency and optimizing power and cooling in realistic conditions.

Findings

Free-energy efficiencies are well-behaved for equilibrium and nonequilibrium resources.

The system can operate with efficiencies bounded by thermodynamic laws.

Optimized parameters enhance power production and cooling performance.

Abstract

We investigate a multiterminal mesoscopic conductor in the quantum Hall regime, subject to temperature and voltage biases. The device can be considered as a nonequilibrium resource acting on a working substance. We previously showed that cooling and power production can occur in the absence of energy and particle currents from a nonequilibrium resource (calling this an N-demon). Here we allow energy or particle currents from the nonequilibrium resource and find that the device seemingly operates at a better efficiency than a Carnot engine. To overcome this problem, we define free-energy efficiencies which incorporate the fact that a nonequilibrium resource is consumed in addition to heat or power. These efficiencies are well behaved for equilibrium and nonequilibrium resources and have an upper bound imposed by the laws of thermodynamics. We optimize power production and cooling in experimentally relevant parameter regimes.