Can a quantum critical state represent a blackbody?

TL;DR

This paper proposes that certain heated quantum critical states can mimic blackbody radiation, emitting at all wavelengths with a Planck-like distribution, involving emergent relativistic particles rather than just photons.

Contribution

It introduces the idea that quantum critical states can serve as blackbody analogs, broadening the understanding of blackbody radiation beyond non-interacting photon models.

Findings

Quantum critical states emit blackbody-like radiation.

Emergent relativistic particles can replace photons in blackbody emission.

Topological quantum critical points exhibit these properties.

Abstract

The blackbody theory of Planck played a seminal role in the development of quantum theory at the turn of the past century. A blackbody cavity is generally thought to be a collection of photons in thermal equilibrium; the radiation emitted is at all wavelengths, and the intensity follows a scaling law, which is Planck's characteristic distribution law. These photons arise from non-interacting normal modes. Here we suggest that certain quantum critical states when heated emit "radiation" at all wavelengths and satisfy all the criteria of a blackbody. An important difference is that the "radiation" does not necessarily consist of non-interacting photons, but also emergent relativistic bosons or fermions. The examples we provide include emergent relativistic fermions at a topological quantum critical point. This perspective on a quantum critical state may be illuminating in many unforeseen ways.