# Upside/Downside statistical mechanics of nonequilibrium Brownian motion. II. Heat transfer and energy partitioning of a free particle

## TL;DR

This paper investigates how energy is partitioned and transferred in a nonequilibrium Brownian particle driven by multiple heat reservoirs, focusing on energy fluctuations during activation and relaxation events.

## Contribution

It introduces a formalism to analyze energy partitioning in Brownian motion, distinguishing trajectories by energy thresholds and examining heat transfer during activation and relaxation.

## Key findings

- Energy partitioning depends on the energy threshold classification.
- Upside and downside events influence heat transfer between reservoirs.
- Relations for energy distribution during activation/relaxation are established.

## Abstract

The energy partitioning during activation and relaxation events under steady-state conditions for a Brownian particle driven by multiple thermal reservoirs of different local temperatures is investigated. Specifically, we apply the formalism derived in a previous article [G. T. Craven and A. Nitzan, J. Chem. Phys. 148, 044101 (2018)] to examine the thermal transport properties of two sub-ensembles of Brownian processes, distinguished at any given time by the specification that all the trajectories in each group have, at that time, energy either above (upside) or below (downside) a preselected energy threshold. Dynamical properties describing energy accumulation and release during activation/relaxation events and relations for upside/downside energy partitioning between thermal reservoirs are derived. The implications for heat transport induced by upside and downside events are discussed.