Charge and spin gaps in the ionic Hubbard model with density-dependent hopping

We calculate the charge gap EC and the spin gap ES of the ionic Hubbard chain including electron-hole symmetric density-dependent hopping. The vanishing of EC (ES) signals a quantum critical point in the charge (spin) sector. Between both critical points, the system is a fully gapped spontaneously dimerized insulator. We focus our study in this region. Including alternation in the hopping, it is possible to perform an adiabatic Thouless pump of one charge per cycle, but with a velocity limited by the size of the gaps.

Automated summary

This study calculates the charge and spin gaps in the ionic Hubbard chain, considering density-dependent hopping with electron-hole symmetry. The disappearance of the charge (spin) gap indicates a quantum critical point in the charge (spin) sector. Between these critical points, the system behaves as a fully gapped spontaneously dimerized insulator. The study focuses on this region and explores the possibility of an adiabatic Thouless pump with alternating hopping, limited by the size of the gaps.