Wave packet dynamics and edge transport in anomalous Floquet topological phases

TL;DR

This paper explores the unique edge transport phenomena in anomalous Floquet topological phases within a periodically driven honeycomb lattice, revealing robust chiral edge modes and their dynamics, with implications for ultracold quantum gases.

Contribution

It introduces a simple model for anomalous Floquet topological phases, analyzing wave packet dynamics and edge transport, highlighting their robustness and experimental relevance.

Findings

Identified anomalous topological phase with opposite chirality edge states.

Demonstrated wave packet dynamics unique to Floquet regimes not seen in equilibrium.

Showed more robust chiral edge motion compared to Haldane phase.

Abstract

The possibility of attaining chiral edge modes under periodic driving has spurred tremendous attention, both theoretically and experimentally, especially in light of anomalous Floquet topological phases that feature vanishing Chern numbers unlike any static counterpart. We here consider a periodically modulated honeycomb lattice and experimentally relevant driving protocols, which allows us to obtain edge modes of various character in a simple model. We calculate the phase diagram over a wide range of parameters and recover an anomalous topological phase with quasienergy gaps harbouring edge states with opposite chirality. Motivated by the advances in single-site control in optical lattices, we investigate wave packet dynamics localized at the edges in distinct Floquet topological regimes that cannot be achieved in equilibrium. We analyse transport properties in edge modes originating from the same bands, but with support at different quasienergies and sublattices as well as possessing different chiralities. We find that an anomalous Floquet topological phase can in general generate more robust chiral edge motion than a Haldane phase. Our results demonstrate that the rich interplay of wave packet dynamics and topological edge states can serve as a versatile tool in ultracold quantum gases in optical lattices.