Floquet prethermalization and Rabi oscillations in optically excited Hubbard clusters

TL;DR

This paper investigates Floquet prethermal states in optically excited Hubbard clusters, revealing conditions for their emergence, characteristics like Rabi oscillations, and the transition to thermalization at higher field strengths.

Contribution

It demonstrates the existence of Floquet prethermal states in resonant and off-resonant conditions, including their Rabi oscillations, using exact-diagonalization and theoretical analysis.

Findings

Floquet prethermal states occur off resonance and at resonance with small fields.

Long-lived states exhibit Rabi oscillations in observables.

Stronger fields lead to thermalization to infinite temperature.

Abstract

We study the properties of Floquet prethermal states in two-dimensional Mott-insulating Hubbard clusters under continuous optical excitation. With exact-diagonalization simulations, we show that Floquet prethermal states emerge not only off resonance, but also for resonant excitation, provided a small field amplitude. In the resonant case, the long-lived quasi-stationary Floquet states are characterized by Rabi oscillations of observables such as double occupation and kinetic energy. At stronger fields, thermalization to infinite temperature is observed. We understand these results in terms of the optically driven two-site Hubbard model and by means of time-dependent perturbation theory.