A mechanical autonomous stochastic heat engine

TL;DR

This paper introduces an autonomous stochastic heat engine composed of coupled mechanical resonators that converts random thermal energy into directed mechanical work, demonstrating negative thermal conductivity and autonomous operation.

Contribution

It presents the first autonomous mechanical stochastic heat engine that uses geometric nonlinearities to convert thermal fluctuations into work without external control.

Findings

Demonstrates negative thermal conductivity in a mechanical system.

Shows autonomous conversion of thermal noise into mechanical oscillations.

Validates the concept of a self-sufficient stochastic heat engine.

Abstract

Stochastic heat engines are devices that generate work from random thermal motion using a small number of highly fluctuating degrees of freedom. Proposals for such devices have existed for more than a century and include the Maxwell demon and the Feynman ratchet. Only recently have they been demonstrated experimentally, using e.g., thermal cycles implemented in optical traps. However, the recent demonstrations of stochastic heat engines are nonautonomous, since they require an external control system that prescribes a heating and cooling cycle, and consume more energy than they produce. This Report presents a heat engine consisting of three coupled mechanical resonators (two ribbons and a cantilever) subject to a stochastic drive. The engine uses geometric nonlinearities in the resonating ribbons to autonomously convert a random excitation into a low-entropy, nonpassive oscillation of the cantilever. The engine presents the anomalous heat transport property of negative thermal conductivity, consisting in the ability to passively transfer energy from a cold reservoir to a hot reservoir.