Browsing by Author "Partridge, Guthrie B."

Now showing 1 - 4 of 4
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    Conversion of an Atomic Fermi Gas to a Long-Lived Molecular Bose Gas
    (American Physical Society, 2003) Strecker, Kevin E.; Partridge, Guthrie B.; Hulet, Randall G.; Rice Quantum Institute
    We have converted an ultracold Fermi gas of Li6 atoms into an ultracold gas of Li26 molecules by adiabatic passage through a Feshbach resonance. Approximately 1.5×105 molecules in the least-bound, v=38, vibrational level of the X1Σ+g singlet state are produced with an efficiency of 50%. The molecules remain confined in an optical trap for times of up to 1 s before we dissociate them by a reverse adiabatic sweep.
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    Formation and propagation of matter-wave soliton trains
    (Nature Publishing Group, 2002) Strecker, Kevin E.; Partridge, Guthrie B.; Truscott, Andrew G.; Hulet, Randall G.; Rice Quantum Institute
    Attraction between the atoms of a Bose-Einstein condensate renders it unstable to collapse, although a condensate with a limited number of atoms [1] can be stabilized [2] by confinement in an atom trap. However, beyond this number the condensate collapses [3, 4, 5]. Condensates constrained to one-dimensional motion with attractive interactions are predicted to form stable solitons, in which the attractive forces exactly compensate for wave-packet dispersion [1]. Here we report the formation of bright solitons of 7Li atoms in a quasi-one-dimensional optical trap, by magnetically tuning the interactions in a stable Bose-Einstein condensate from repulsive to attractive. The solitons are set in motion by offsetting the optical potential, and are observed to propagate in the potential for many oscillatory cycles without spreading. We observe a soliton train, containing many solitons; repulsive interactions between neighbouring solitons are inferred from their motion.
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    Pairing and Phase Separation in a Polarized Fermi Gas
    (American Association for the Advancement of Science, 2006) Partridge, Guthrie B.; Li, Wenhui; Kamar, Ramsey I.; Liao, Yean-an; Hulet, Randall G.
    We report the observation of pairing in a gas of atomic fermions with unequal numbers of two components. Beyond a critical polarization, the gas separates into a phase that is consistent with a superfluid paired core surrounded by a shell of normal unpaired fermions. The critical polarization diminishes with decreasing attractive interaction. For near-zero polarization, we measured the parameter β = –0.54 ± 0.05, describing the universal energy of a strongly interacting paired Fermi gas, and found good agreement with recent theory. These results are relevant to predictions of exotic new phases of quark matter and of strongly magnetized superconductors.
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    Spin-imbalance in a one-dimensional Fermi gas
    (Nature Publishing Group, 2010) Liao, Yean-an; Rittner, Ann Sophie C.; Paprotta, Tobias; Li, Wenhui; Partridge, Guthrie B.; Hulet, Randall G.; Baur, Stefan K.; Mueller, Erich J.; Rice Quantum Institute
    Superconductivity and magnetism generally do not coexist. Changing the relative number of up and down spin electrons disrupts the basic mechanism of superconductivity, where atoms of opposite momentum and spin form Cooper pairs. Nearly forty years ago Fulde and Ferrell [1] and Larkin and Ovchinnikov [2] (FFLO) proposed an exotic pairing mechanism in which magnetism is accommodated by the formation of pairs with finite momentum. Despite intense theoretical and experimental efforts, however, polarized superconductivity remains largely elusive [3]. Unlike the three-dimensional (3D) case, theories predict that in one dimension (1D) a state with FFLO correlations occupies a major part of the phase diagram [4, 5, 6, 7, 8, 9, 10, 11, 12]. Here we report experimental measurements of density profiles of a two-spin mixture of ultracold [6] Li atoms trapped in an array of 1D tubes (a system analogous to electrons in 1D wires). At finite spin imbalance, the system phase separates with an inverted phase profile, as compared to the 3D case. In 1D, we find a partially polarized core surrounded by wings which, depending on the degree of polarization, are composed of either a completely paired or a fully polarized Fermi gas. Our work paves the way to direct observation and characterization of FFLO pairing.