Nonequilibrium Tuning of the Thermal Casimir Effect

TL;DR

This paper demonstrates how applying an electric field to systems with Brownian charges can modulate thermal Casimir forces by creating nonequilibrium steady states, reducing normal attraction and inducing lateral forces.

Contribution

It introduces a method to control thermal Casimir forces via nonequilibrium states, combining numerical simulations and analytical theory for validation.

Findings

Electric fields reduce normal Casimir attraction.

Nonequilibrium states generate lateral drag forces.

Method enables force tuning in nanodevices.

Abstract

In net-neutral systems correlations between charge fluctuations generate strong attractive thermal Casimir forces and engineering these forces to optimize nanodevice performance is an important challenge. We show how the normal and lateral thermal Casimir forces between two plates containing Brownian charges can be modulated by decorrelating the system through the application of an electric field, which generates a nonequilibrium steady state with a constant current in one or both plates, reducing the ensuing fluctuation-generated normal force while at the same time generating a lateral drag force. This hypothesis is confirmed by detailed numerical simulations as well as an analytical approach based on stochastic density functional theory.