Non-equilibrium Fractional Hall Response After a Topological Quench

TL;DR

This paper investigates the non-equilibrium Hall response of a lattice system after a topological quench, revealing universal fractional changes in Hall conductivity and exploring experimental observations in cold-atom setups.

Contribution

It introduces a theoretical framework for understanding the fractional Hall response post-quench and demonstrates universality in the Haldane model.

Findings

Hall conductivity changes by two-thirds of the quantum after a quench

The Hall response exhibits a crossover from fractional to integer values

Finite-size effects and harmonic confinement influence the observed response

Abstract

We theoretically study the Hall response of a lattice system following a quench where the topology of a filled band is suddenly changed. In the limit where the physics is dominated by a single Dirac cone, we find that the change in the Hall conductivity is two-thirds of the quantum of conductivity. We explore this universal behavior in the Haldane model, and discuss cold-atom experiments for its observation. Beyond linear response, the Hall effect crosses over from fractional to integer values. We investigate finite-size effects, and the role of the harmonic confinement.