Quantum Geometric Entropy Production and Entropy Hall Effect

TL;DR

This paper develops a quantum-geometric theory of entropy transport in Bloch electrons, linking Berry curvature and quantum metric to entropy production and Hall effects, with implications for experimental probes of quantum geometry.

Contribution

It introduces a microscopic entropy continuity equation incorporating quantum geometry, revealing the quantum metric as a key source of entropy production and predicting an entropy Hall effect.

Findings

Quantum metric drives leading entropy production.

Predicted entropy Hall effect related to Berry curvature.

Universal relations between entropy and charge currents.

Abstract

Quantum geometry, encoded in the Berry curvature and quantum metric, has unified diverse anomalous transport phenomena in solids, yet a microscopic quantum-geometric theory of entropy transport for Bloch electrons is still lacking. We formulate an entropy continuity equation for noninteracting fermions driven by an electric field, starting from the von Neumann entropy, and obtain quantum-mechanical expressions for the entropy current density and entropy production rate. Introducing relaxation through a relaxation-time dissipator, we identify the quantum metric as the origin of the leading entropy production, providing a direct microscopic diagnostic of dissipation in both the extrinsic Drude response and an intrinsic nonlinear Ohmic contribution controlled by quantum metric. We further predict an entropy Hall effect arising from the Berry curvature and show that it obeys an Onsager reciprocal relation with the anomalous Nernst effect under a temperature gradient. Finally, we establish universal relations connecting entropy and charge currents under DC and AC driving, offering experimentally accessible probes of quantum geometry through nonequilibrium entropy flow.