Efficiency fluctuations and noise induced refrigerator-to-heater transition in information engines

TL;DR

This paper investigates how noise affects the efficiency of colloidal information engines, revealing a noise-induced transition from refrigerator to heater states and the conditions under which efficiency can surpass unity.

Contribution

It provides a comprehensive phase-space analysis of noisy information engines, demonstrating efficiency fluctuations, a noise-driven transition, and testing the generalized fluctuation theorem.

Findings

Maximum average efficiency occurs at non-zero noise levels.

Efficiency distribution switches from bimodal to unimodal with noise.

A noise-driven transition from refrigerator to heater states is identified.

Abstract

Understanding noisy information engines is a fundamental problem of non-equilibrium physics, particularly in biomolecular systems agitated by thermal and active fluctuations in the cell. By the generalized second law of thermodynamics, the efficiency of these engines is bounded by the mutual information passing through their noisy feedback loop. Yet, direct measurement of the interplay between mutual information and energy has so far been elusive. To allow such examination, we explore here the entire phase-space of a noisy colloidal information engine, and study efficiency fluctuations due to the stochasticity of the mutual information and extracted work. We find that the average efficiency is maximum for non-zero noise level, at which the distribution of efficiency switches from bimodal to unimodal, and the stochastic efficiency often exceeds unity. We identify a line of anomalous, noise-driven equilibrium states that defines a refrigerator-to-heater transition, and test the generalized integral fluctuation theorem for continuous engines.