Violation of the fluctuation-dissipation theorem in time-dependent mesoscopic heat transport

TL;DR

This paper demonstrates that in mesoscopic heat transport, the spectral density of energy flux fluctuations deviates from the fluctuation-dissipation theorem at finite frequencies, revealing additional noise that persists even at zero temperature.

Contribution

It shows that the fluctuation-dissipation theorem does not hold at finite frequencies in mesoscopic heat transport, uncovering extra noise contributions.

Findings

Fluctuating energy flux is not solely determined by thermal conductance at finite frequencies.

Additional noise exists beyond standard fluctuation-dissipation predictions.

Fluctuations persist at zero temperature despite vanishing thermal conductance.

Abstract

We have analyzed the spectral density of fluctuations of the energy flux through a mesoscopic constriction between two equilibrium reservoirs. It is shown that at finite frequencies, the fluctuating energy flux is not related to the thermal conductance of the constriction by the standard fluctuation-dissipation theorem, but contains additional noise. The main physical consequence of this extra noise is that the fluctuations do not vanish at zero temperature together with the vanishing thermal conductance.