Hall Response and Edge Current Dynamics in Chern Insulators out of Equilibrium

TL;DR

This paper studies the non-equilibrium transport in Chern insulators after a quantum quench, revealing that Hall conductance and edge current dynamics deviate from topological invariants and are described by a Generalized Gibbs Ensemble.

Contribution

It provides explicit analysis of Hall response and edge current dynamics post-quench in the Haldane model, highlighting the non-topological nature of these observables out of equilibrium.

Findings

Hall conductance is not related to the Chern number after a quench.

Edge currents evolve towards a Generalized Gibbs Ensemble at late times.

Open boundary conditions influence the edge current dynamics.

Abstract

We investigate the transport properties of Chern insulators following a quantum quench between topological and non-topological phases. Recent works have shown that this yields an excited state for which the Chern number is preserved under unitary evolution. However, this does not imply the preservation of other physical observables, as we stressed in our previous work. Here we provide an analysis of the Hall response following a quantum quench in an isolated system, with explicit results for the Haldane model. We show that the Hall conductance is no longer related to the Chern number in the post-quench state, in agreement with previous work. We also examine the dynamics of the edge currents in finite-size systems with open boundary conditions along one direction. We show that the late-time behavior is captured by a Generalized Gibbs Ensemble, after multiple traversals of the sample. We discuss the effects of generic open boundary conditions and confinement potentials.