Revealing the topological nature of the bond order wave in a strongly correlated quantum system

TL;DR

This paper uncovers the topological nature of the bond order wave phase in a strongly correlated quantum system, revealing topologically protected edge modes and proposing an experimental detection scheme.

Contribution

It identifies a topological sector in the bond order wave phase of the extended Fermi-Hubbard model, previously hidden due to boundary effects, and suggests a method to observe it in finite systems.

Findings

Topological sector characterized by degenerate bulk states.

Presence of topologically protected edge modes.

Implementation scheme in quantum simulators.

Abstract

We investigate the topological properties of the bond order wave phase arising in the extended Fermi-Hubbard model. In particular, we uncover a topological sector, which remained elusive in previous finite-size numerical studies due to boundary effects. We first show that, for an infinite system, the bond order wave regime is characterized by two degenerate bulk states corresponding to the trivial and topological sectors. The latter turns out to be indeed characterized by an even degeneracy of the entanglement spectrum and longe-range order of a string correlation function. For finite size systems, we show that the topological sector can be stabilized by imposing a suitable border potential. This therefore provides a concrete protocol for the observation of topologically protected degenerate edge modes in finite-size systems. Furthermore, we show that the bulk of the system is characterized by exotic solitonic solutions interpolating between the trivial and topological sectors. Finally, we propose an implementation and detection scheme of this strongly-correlated topological phase in a quantum simulator based on dipolar Fermi gases in optical lattices.