Charge excitation dynamics in bosonic fractional Chern insulators

TL;DR

This study uses DMRG simulations to investigate the out-of-equilibrium edge dynamics of bosonic fractional Chern insulators, revealing chiral propagation of local perturbations and density leakage that challenge simple theoretical models.

Contribution

It provides the first detailed analysis of the dynamical response of fractional Chern insulators to local perturbations, highlighting their unique chiral edge behavior and deviations from idealized theories.

Findings

Edge perturbations propagate chirally regardless of strength

Density leaks from edge into bulk, complicating theoretical descriptions

Chiral behavior differs from non-interacting models with counter-propagating states

Abstract

The experimental realization of the Harper-Hofstadter model in ultra-cold atomic gases has placed fractional states of matter in these systems within reach---a fractional Chern insulator state (FCI) is expected to emerge for sufficiently strong interactions when half-filling the lowest band. The experimental setups naturally allow to probe the dynamics of this topological state, yet little is known about its out-of-equilibrium properties. We explore, using density matrix renormalization group (DMRG) simulations, the response of the FCI state to spatially localized perturbations. After confirming the static properties of the phase we show that the characteristic, gapless features are clearly visible in the edge dynamics. We find that a local edge perturbation in this model propagates chirally independent of the perturbation strength. This contrasts the behavior of single particle models with counter-propagating edge states, such as the non-interacting Harper-Hofstadter model, where the chirality is manifest only for weak perturbations. Additionally, our simulations show that there is inevitable density leakage from the first row of sites into the bulk, preventing a naive chiral Luttinger theory interpretation of the dynamics.