Low-energy doublons in the ac-driven two-species Hubbard model

TL;DR

This paper demonstrates that a high-frequency bichromatic external field can create low-energy doublon states in a driven two-species Hubbard model, confirmed by asymptotic analysis and numerical simulations.

Contribution

It introduces a novel mechanism for stabilizing low-energy doublons using high-frequency bichromatic driving in a two-species Hubbard model.

Findings

High-frequency bichromatic field sustains low-energy doublons.

Asymptotic analysis matches numerical simulations.

Doublons involve different species occupying neighboring sites.

Abstract

The hopping dynamics of two fermionic species with different effective masses in the one-dimensional Hubbard model driven by an external field is theoretically investigated. A multiple-time-scale asymptotic analysis of the driven asymmetric Hubbard model shows that a high-frequency bichromatic external field can sustain a new kind of low-energy particle bound state (doublon), in which two fermions of different species occupy nearest neighbor sites and co-tunnel along the lattice. The predictions of the asymptotic analysis are confirmed by direct numerical simulations of the two-particle Hubbard Hamiltonian.