Transient fluctuation-induced forces in driven electrolytes after an electric field quench

TL;DR

This paper investigates how fluctuations in driven electrolytes after a sudden electric field application generate long-range, time-dependent fluctuation-induced forces, revealing complex non-equilibrium behaviors and potential control mechanisms.

Contribution

It extends previous work by analyzing the long-time, long-distance correlations and forces in electrolytes after a field quench, highlighting diffusive dynamics and power-law decay of forces.

Findings

Long-range FIFs act on confining plates with power-law temporal decay.

Charge and density correlations become diffusive over long distances.

Nonequilibrium fluctuations influence the dynamics of immersed objects.

Abstract

Understanding how electrolyte solutions behave out of thermal equilibrium is a long-standing endeavor in many areas of chemistry and biology. Although mean-field theories are widely used to model the dynamics of electrolytes, it is also important to characterize the effects of fluctuations in these systems. In a previous work, we showed that the dynamics of the ions in a strong electrolyte that is driven by an external electric field can generate long-ranged correlations manifestly different from the equilibrium screened correlations; in the nonequilibrium steady state, these correlations give rise to a novel long-range fluctuation-induced force (FIF). Here, we extend these results by considering the dynamics of the strong electrolyte after it is quenched from thermal equilibrium upon the application of a constant electric field. We show that the asymptotic long-distance limit of both charge and density correlations is generally diffusive in time. These correlations give rise to long-ranged FIFs acting on the neutral confining plates with long-time regimes that are governed by power-law temporal decays toward the steady-state value of the force amplitude. These findings show that nonequilibrium fluctuations have nontrivial implications on the dynamics of objects immersed in a driven electrolyte, and they could be useful for exploring new ways of controlling long-distance forces in charged solutions.