Emergent Energy Dissipation in Quantum Limit

TL;DR

This paper reveals that energy dissipation occurs in quantum Hall systems of graphene through Joule heat, despite topological protection of charge transport, highlighting overlooked dissipation mechanisms in topological quantum circuits.

Contribution

It introduces a microscopic model showing energy dissipation via Joule heat in the quantum Hall regime, challenging the assumption of dissipationless topological transport.

Findings

Energy dissipation occurs as Joule heat in quantum Hall systems.

Electrons can transition between equilibrium and non-equilibrium states without affecting quantized resistance.

Relaxation of non-equilibrium electrons causes energy dissipation along edge states.

Abstract

Energy dissipation is of fundamental interest and crucial importance in quantum systems. However, whether energy dissipation can emerge inside topological systems remains a question, especially when charge transport is topologically protected and quantized. As a hallmark, we propose a microscopic picture that illustrates energy dissipation in the quantum Hall (QH) plateau regime of graphene. Despite the quantization of Hall, longitudinal, and two-probe resistances (dubbed as the quantum limit), we find that the energy dissipation emerges in the form of Joule heat. By analyzing the energy distribution of electrons, it is found that electrons can evolve between equilibrium and non-equilibrium without inducing extra two-probe resistance. The relaxation of non-equilibrium electrons results in the dissipation of energy along the QH edge states. Eventually, we suggest probing the phenomenon by measuring local temperature increases in experiments and reconsidering the dissipation typically ignored in realistic topological circuits.