Shuttling heat across 1D homogenous nonlinear lattices with a Brownian heat motor

TL;DR

This paper demonstrates how directed heat flux can be achieved in 1D nonlinear lattices through dynamic symmetry breaking, using modulated thermal baths, with results supported by computer simulations showing robustness across lattice sizes.

Contribution

It introduces a novel mechanism for inducing and controlling heat flux in homogeneous nonlinear lattices via temperature modulation, including harmonic mixing, which was previously unexplored.

Findings

Directed heat flux is achievable without net thermal bias.

The heat flux persists and is robust with increasing lattice size.

Sign reversal of heat flux can occur due to dynamical symmetry breaking.

Abstract

We investigate directed thermal heat flux across 1D homogenous nonlinear lattices when no net thermal bias is present on average. A nonlinear lattice of Fermi-Pasta-Ulam-type or Lennard-Jones-type system is connected at both ends to thermal baths which are held at the same temperature on temporal average. We study two different modulations of the heat bath temperatures, namely: (i) a symmetric, harmonic ac-driving of temperature of one heat bath only and (ii) a harmonic mixing drive of temperature acting on both heat baths. While for case (i) an adiabatic result for the net heat transport can be derived in terms of the temperature dependent heat conductivity of the nonlinear lattice a similar such transport approach fails for the harmonic mixing case (ii). Then, for case (ii), not even the sign of the resulting Brownian motion induced heat flux can be predicted a priori. A non-vanishing heat flux (including a non-adiabatic reversal of flux) is detected which is the result of an induced dynamical symmetry breaking mechanism in conjunction with the nonlinearity of the lattice dynamics. Computer simulations demonstrate that the heat flux is robust against an increase of lattice sizes. The observed ratchet effect for such directed heat currents is quite sizable for our studied class of homogenous nonlinear lattice structures, thereby making this setup accessible for experimental implementation and verification.