Lifetime of double occupancies in the Fermi-Hubbard model

TL;DR

This paper studies the decay dynamics of double occupancies (doublons) in a strongly interacting Fermi-Hubbard system, combining theoretical diagrammatic methods and ultracold atom experiments, revealing exponential lifetime scaling and decay mechanisms.

Contribution

It provides the first combined theoretical and experimental analysis of doublon lifetimes in the strongly interacting regime, highlighting the role of background correlations.

Findings

Doublon lifetime scales exponentially with the ratio of on-site repulsion to bandwidth.

Decay involves excitation of multiple particle-hole pairs to absorb doublon energy.

The background state’s strongly interacting nature is essential for accurate lifetime estimates.

Abstract

We investigate the decay of artificially created double occupancies in a repulsive Fermi-Hubbard system in the strongly interacting limit using diagrammatic many-body theory and experiments with ultracold fermions on optical lattices. The lifetime of the doublons is found to scale exponentially with the ratio of the on-site repulsion to the bandwidth. We show that the dominant decay process in presence of background holes is the excitation of a large number of particle hole pairs to absorb the energy of the doublon. We also show that the strongly interacting nature of the background state is crucial in obtaining the correct estimate of the doublon lifetime in these systems. The theoretical estimates and the experimental data are in fair quantitative agreement.