Two-doublon Bloch oscillations in the mass-imbalanced extended Fermi-Hubbard model

TL;DR

This paper studies how nearest-neighbor interactions affect doublon Bloch oscillations in a mass-imbalanced extended Fermi-Hubbard model, revealing resonance conditions where doublons behave like free particles.

Contribution

It introduces an effective Hamiltonian for doublons considering nearest-neighbor interactions and demonstrates how small changes in these interactions qualitatively change doublon dynamics, including resonance behavior.

Findings

Doublons can behave as free hard-core bosons at resonance.

Nearest-neighbor interaction $V$ significantly influences doublon Bloch oscillations.

Numerical simulations confirm the theoretical predictions in 1D and 2D systems.

Abstract

Interactions between particles normally induce the decay of the particles Bloch oscillations (BOs) in a periodic lattice. In the limit of strong on-site interactions, spin-$1/2$ fermions may form doublon bound states and undergo BOs in the presence of a tilted potential. Here we investigate the impact of nearest-neighbor interaction $V$ on the multi-doublon BOs in a mass-imbalanced extended Fermi-Hubbard model. We derive an effective Hamiltonian for doublons, and show that a slight change in $V$ can qualitatively alter their dynamic behaviors. Notably, at a resonance point, the doublons behave like free hard-core bosons. Under a tilted potential, the system may exhibit different types of multi-doublon BOs at or deviation from the resonance point. Numerical results are presented to demonstrate our conclusions in both one- and two-dimensional systems.