Multiple particle-hole pair creation in the Fermi-Hubbard model by a pump laser

TL;DR

This paper investigates how a pump laser can induce multiple particle-hole pair creation in the strongly correlated Fermi-Hubbard model, revealing resonant conditions for creating multiple pairs near integer multiples of the Mott gap.

Contribution

It demonstrates that oscillating electric fields can resonantly generate multiple particle-hole pairs in the Fermi-Hubbard model, extending understanding of laser-induced excitations in strongly correlated systems.

Findings

Resonant creation of particle-hole pairs at the Mott gap frequency.

Multiple pairs can be generated when the pump frequency is near an integer multiple of the gap.

The effective hopping rate is reduced by the pump, analogous to a quantum quench.

Abstract

We study the Fermi-Hubbard model in the strongly correlated Mott phase under the influence of a harmonically oscillating electric field, e.g., a pump laser. In the Peierls representation, this pump field can be represented as an oscillating phase of the hopping rate $J(t)$, such that the effective time-averaged rate $\bar J$ is reduced, i.e., switching the pump laser suddenly is analogous to a quantum quench. Apart from this time-averaged rate $\bar J$, it is well known that the oscillating component of $J(t)$ can resonantly create particle-hole pairs if the pump frequency $\omega_{\rm pump}$ equals (or a little exceeds) the Mott gap. In addition, we find that it is possible to create multiple pairs if $\omega_{\rm pump}$ is near an integer multiple of the gap. These findings should be relevant for pump-probe experiments.