Signature of resonant modes in radiative heat current noise spectrum

TL;DR

This paper demonstrates that the noise spectrum of radiative heat current reveals resonant modes as sharp peaks, providing a direct way to probe heat-carrying excitations in systems like superconducting circuits and 2D metals.

Contribution

It introduces the concept that heat current noise spectrum can directly detect resonant modes, which are invisible in average heat current measurements.

Findings

Resonant modes produce sharp peaks in the heat current noise spectrum.

The width of the peaks relates to the mode lifetime.

Applications demonstrated in superconducting circuits and 2D metals.

Abstract

Radiative heat transfer between bodies is often dominated by a narrow resonance in the transmission, e.~g. due to a cavity mode or a surface excitation. However, this resonant character is not visible in the average heat current. Here, we show that the noise spectrum of heat current can serve as a direct probe of the heat-carrying excitations. Namely, the resonant mode produces a sharp peak in the noise spectrum with a width related to the mode lifetime. We demonstrate that heat transfer in realistic superconducting circuits or between two-dimensional metals can realize our predictions.