title: Correlations and pair formation in a repulsively interacting Fermi gas.
abstract: A degenerate Fermi gas is rapidly quenched into the regime of strong effective repulsion near a Feshbach resonance. The spin fluctuations are monitored using speckle imaging and, contrary to several theoretical predictions, the samples remain in the paramagnetic phase for an arbitrarily large scattering length. Over a wide range of interaction strengths a rapid decay into bound pairs is observed over times on the order of 10ℏ/E(F), preventing the study of equilibrium phases of strongly repulsive fermions. Our work suggests that a Fermi gas with strong short-range repulsive interactions does not undergo a ferromagnetic phase transition.
authors.affiliation: MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Sanner
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Su
authors.forename: Wujie
authors.initials: W
authors.lastname: Huang
authors.forename: Aviv
authors.initials: A
authors.lastname: Keshet
authors.forename: Jonathon
authors.initials: J
authors.lastname: Gillen
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Ketterle