Characterizing autonomous Maxwell demons

TL;DR

This paper clarifies the differences between traditional autonomous Maxwell demons and recent linear device models, emphasizing the importance of local current fluctuation measurements to distinguish true current inversion from apparent effects.

Contribution

It introduces a local measurement approach based on current fluctuations to differentiate genuine Maxwell demon behavior from similar linear devices.

Findings

Current inversion in Maxwell demons can be distinguished from apparent effects by local fluctuation measurements.

Linear devices may mimic current inversion without true energy transfer reversal.

Local current fluctuation analysis reveals the fundamental difference between genuine and apparent current inversions.

Abstract

We distinguish traditional implementations of autonomous Maxwell demons from related linear devices that were recently proposed, not relying on the notions of measurements and feedback control. In both cases a current seems to flow against its spontaneous direction (imposed, e.g., by a thermal or electric gradient) without external energy intake. However, in the latter case, this current inversion may only be apparent. Even if the currents exchanged between a system and its reservoirs are inverted (by creating additional independent currents between system and demon), this is not enough to conclude that the original current through the system has been inverted. We show that this distinction can be revealed locally by measuring the fluctuations of the system-reservoir currents.