Dynamically induced doublon repulsion in the Fermi-Hubbard model probed by a single-particle density of states

TL;DR

This paper demonstrates how off-resonant ac fields can dynamically switch doublon interactions in the Fermi-Hubbard model from attractive to repulsive, with signatures observable in the single-particle density of states.

Contribution

The study introduces an effective Hamiltonian in the high-frequency limit that reveals controllable doublon interactions via ac field power, supported by nonequilibrium dynamical mean-field theory simulations.

Findings

Doublon interactions can be tuned from attractive to repulsive using ac fields.

Signature of dynamical doublon repulsion appears in the time-averaged single-particle density of states.

The effective Hamiltonian accurately describes doublon physics in the high-frequency regime.

Abstract

We investigate the possibility to control dynamically the interactions between repulsively bound pairs of fermions (doublons) in correlated systems with off-resonant ac fields. We introduce an effective Hamiltonian that describes the physics of doublons up to the second-order in the high-frequency limit. It unveils that the doublon interaction, which is attractive in equilibrium, can be completely suppressed and then switched to repulsive by varying the power of the ac field. We show that the signature of the dynamical repulsion between doublons can be found in the single-fermion density of states averaged in time. Our results are further supported by nonequilibrium dynamical mean-field theory simulations for the half-filled Fermi-Hubbard model.