SSH model with long-range hoppings: topology, driving and disorder

TL;DR

This paper explores an extended SSH model with long-range hoppings, analyzing how odd and even hoppings affect topology, and demonstrates methods to engineer topological phases and assess disorder effects.

Contribution

It introduces a generalized SSH model with long-range hoppings, revealing their distinct impacts on topology and proposing driving techniques to engineer topological phases.

Findings

Even hoppings break certain symmetries but preserve quantized Zak phase.

Odd hoppings enable larger topological invariants and more edge states.

Disorder analysis shows robustness of edge states under certain conditions.

Abstract

The Su-Schrieffer-Heeger (SSH) model describes a finite one-dimensional dimer lattice with first-neighbour hoppings populated by non-interacting electrons. In this work we study a generalization of the SSH model including longer-range hoppings, what we call the extended SSH model. We show that the presence of odd and even hoppings has a very different effect on the topology of the chain. On one hand, even hoppings break particle-hole and sublattice symmetry, making the system topologically trivial, but the Zak phase is still quantized due to the presence of inversion symmetry. On the other hand, odd hoppings allow for phases with a larger topological invariant. This implies that the system supports more edge states in the band's gap. We propose how to engineer those topological phases with a high-frequency driving. Finally, we include a numerical analysis on the effect of diagonal and off-diagonal disorder in the edge states properties.