title: Pairing in few-fermion systems with attractive interactions.
abstract: We study quasi-one-dimensional few-particle systems consisting of one to six ultracold fermionic atoms in two different spin states with attractive interactions. We probe the system by deforming the trapping potential and by observing the tunneling of particles out of the trap. For even particle numbers, we observe a tunneling behavior that deviates from uncorrelated single-particle tunneling indicating the existence of pair correlations in the system. From the tunneling time scales, we infer the differences in interaction energies of systems with different number of particles, which show a strong odd-even effect, similar to the one observed for neutron separation experiments in nuclei.
authors.affiliation: Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, 69120 Heidelberg, Germany and Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Zürn
authors.forename: A N
authors.initials: AN
authors.lastname: Wenz
authors.forename: S
authors.initials: S
authors.lastname: Murmann
authors.forename: A
authors.initials: A
authors.lastname: Bergschneider
authors.forename: T
authors.initials: T
authors.lastname: Lompe
authors.forename: S
authors.initials: S
authors.lastname: Jochim