Topological Rice-Mele model in an emergent lattice: Exact diagonalization approach

TL;DR

This study uses exact diagonalization to explore phases in a driven one-dimensional fermionic system, revealing an emergent Rice-Mele model, density wave configurations, and localized fractional charge modes, contrasting with prior mean field predictions.

Contribution

It demonstrates the emergence of a Rice-Mele model and fractionalized excitations in a driven lattice using exact diagonalization, advancing understanding beyond mean field approaches.

Findings

Emergent Rice-Mele model near vanishing intraband tunneling

Density wave configurations of composites observed

Localized modes with fractional particle charge identified

Abstract

Using exact diagonalization methods we study possible phases in a one dimensional model of two differently populated fermionic species in a periodically driven optical lattice. The shaking amplitude and frequency are chosen to resonantly drive $s-p$ transition while minimizing the standard intraband tunnelings. We numerically verify that in the vicinity of vanishing intraband tunnelings the system, for an appropriate filling, shows an emergent density wave configuration of composites. The majority fermions moving in such a lattice mimic the celebrated Rice-Mele model. Far away from that region structure changes to clustered phase, with intermediate phase abundantly populated by defects of the density wave. These defects lead to loclaized modes carrying fractional particle charge. The results obtained are compared with earlier mean field approximation predictions.