Stationary state of harmonic chains driven by boundary resetting

TL;DR

This paper investigates the nonequilibrium steady state of a harmonic chain with boundary walls undergoing stochastic resetting, revealing non-Gaussian velocity distributions, specific correlation decay behaviors, and an exactly computable energy current.

Contribution

It introduces a model of harmonic chains driven by boundary resetting, providing analytical and numerical insights into velocity correlations and energy currents in nonequilibrium steady states.

Findings

Velocity distribution remains non-Gaussian with decaying kurtosis as system size increases.

Two-time velocity correlations decay as t^{-1/2} at large times.

Exact expression for the average energy current in the thermodynamic limit.

Abstract

We study the nonequilibrium steady state (NESS) of an ordered harmonic chain of $N$ oscillators connected to two walls which undergo diffusive motion with stochastic resetting. The intermittent resettings of the walls effectively emulate two nonequilibrium reservoirs that exert temporally correlated forces on the boundary oscillators. These reservoirs are characterized by the diffusion constant and resetting rates of the walls. We find that, for any finite $N$, the velocity distribution remains non-Gaussian, as evidenced by a non-zero bulk kurtosis that decays $\sim N^{-1}$. We calculate the spatio-temporal correlation of the velocity of the oscillators $\langle v_l(t) v_{l'}(t') \rangle$ both analytically as well as using numerical simulation. The signature of the boundary resetting is present at the bulk in terms of the two-time velocity correlation of a single oscillator and the equal-time spatial velocity correlation. For the resetting driven chain, the two-time velocity correlation decay as $t^{-\frac{1}{2}}$ at the large time, and there exists a non-zero equal-time spatial velocity correlation $\langle v_l(t) v_{l'}(t') \rangle$ when $l \neq l'$. A non-zero average energy current will flow through the system when the boundary walls reset to their initial position at different rates. This average energy current can be computed exactly in the thermodynamic limit. Numerically we show that the distribution of the instantaneous energy current at the boundary is independent of the system size. However, the distribution of the instantaneous energy current in the bulk approaches a stationary distribution in the thermodynamic limit.