title: Observation of elastic doublon decay in the Fermi-Hubbard model.
abstract: We investigate the decay of highly excited states of ultracold fermions in a three-dimensional optical lattice. Starting from a repulsive Fermi-Hubbard system near half filling, we generate additional doubly occupied sites (doublons) by lattice modulation. The subsequent relaxation back to thermal equilibrium is monitored over time. The measured absolute doublon lifetime covers 2 orders of magnitude. In units of the tunneling time h/J it is found to depend exponentially on the ratio of on-site interaction energy U to kinetic energy J. We argue that the dominant mechanism for the relaxation is a simultaneous many-body process involving several single fermions as scattering partners. A many-body calculation is carried out using diagrammatic methods, yielding fair agreement with the data.
authors.affiliation: Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Niels
authors.initials: N
authors.lastname: Strohmaier
authors.forename: Daniel
authors.initials: D
authors.lastname: Greif
authors.forename: Robert
authors.initials: R
authors.lastname: Jördens
authors.forename: Leticia
authors.initials: L
authors.lastname: Tarruell
authors.forename: Henning
authors.initials: H
authors.lastname: Moritz
authors.forename: Tilman
authors.initials: T
authors.lastname: Esslinger
authors.forename: Rajdeep
authors.initials: R
authors.lastname: Sensarma
authors.forename: David
authors.initials: D
authors.lastname: Pekker
authors.forename: Ehud
authors.initials: E
authors.lastname: Altman
authors.forename: Eugene
authors.initials: E
authors.lastname: Demler