Floquet engineering of binding in doped and photo-doped Mott insulators

TL;DR

This paper explores how Floquet engineering can enhance binding energies in doped Mott insulators by manipulating spin and pairing fluctuations, with implications for experimental realization of Hubbard excitons.

Contribution

It introduces a generalized $t$-$J$ model for doped Mott insulators and demonstrates Floquet engineering's ability to significantly enhance binding energies.

Findings

Binding energies are similar in chemically and photo-doped regimes.

Floquet driving can substantially increase binding energies.

Estimated lifetimes of photo-doped states under periodic driving.

Abstract

We investigate the emergence of bound states in chemically and photo-doped Mott insulators, mediated by spin and $\eta$-pairing fluctuations within both 2-leg ladder and 2D systems. To effectively describe the photo and chemically doped state on the same footings, we employ the Schrieffer-Wolff transformation, resulting in a generalized $t$-$J$ model. Our results demonstrate that the binding energies and localization length in the chemically and photo-doped regimes are comparable, with $\eta$-pairing fluctuations not playing a crucial role. Furthermore, we show that manipulating the binding is possible through external periodic driving, a technique known as Floquet engineering, leading to significantly enhanced binding energies. We also roughly estimate the lifetime of photo-doped states under periodic driving conditions based on the Fermi golden rule. Lastly, we propose experimental protocols for realizing Hubbard excitons in cold-atom experiments.