Browsing by Author "Partridge, G.B."

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    Bright matter wave solitons in Bose–Einstein condensates
    (IOP Publishing, 2003) Strecker, K.E.; Partridge, G.B.; Truscott, A.G.; Hulet, R.G.; Rice Quantum Institute
    We review recent experimental and theoretical work on the creation of bright matter wave solitons in Bose–Einstein condensates. In two recent experiments, solitons are formed from Bose–Einstein condensates of  7Li by utilizing a Feshbach resonance to switch from repulsive to attractive interactions. The solitons are made to propagate in a one-dimensional potential formed by a focused laser beam. For repulsive interactions, the wavepacket undergoes dispersive wavepacket spreading, while for attractive interactions, localized solitons are formed. In our experiment, a multi-soliton train containing up to ten solitons is observed to propagate without spreading for a duration of 2 s. Adjacent solitons are found to interact repulsively, in agreement with a calculation based on the nonlinear Schrödinger equation assuming that the soliton train is formed with an alternating phase structure. The origin of this phase structure is not entirely clear.
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    Bright Soliton Trains of Trapped Bose-Einstein Condensates
    (American Physical Society, 2002) Khawaja, U. Al; Stoof, H.T.C.; Hulet, R.G.; Strecker, K.E.; Partridge, G.B.; Rice Quantum Institute
    We variationally determine the dynamics of bright soliton trains composed of harmonically trapped Bose-Einstein condensates with attractive interatomic interactions. In particular, we obtain the interaction potential between two solitons. We also discuss the formation of soliton trains due to the quantum mechanical phase fluctuations of a one-dimensional condensate.
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    Deformation of a Trapped Fermi Gas with Unequal Spin Populations
    (American Physical Society, 2006) Partridge, G.B.; Li, Wenhui; Liao, Y.A.; Hulet, R.G.; Haque, M.; Stoof, H.T.C.; Rice Quantum Institute
    The real-space densities of a polarized strongly interacting two-component Fermi gas of Li6 atoms reveal two low-temperature regimes, both with a fully paired core. At the lowest temperatures, the unpolarized core deforms with increasing polarization. Sharp boundaries between the core and the excess unpaired atoms are consistent with a phase separation driven by a first-order phase transition. In contrast, at higher temperatures the core does not deform but remains unpolarized up to a critical polarization. The boundaries are not sharp in this case, indicating a partially polarized shell between the core and the unpaired atoms. The temperature dependence is consistent with a tricritical point in the phase diagram.
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    Metastability in Spin-Polarized Fermi Gases
    (American Physical Society, 2011) Liao, Y.A.; Revelle, M.; Paprotta, T.; Rittner, A.S.C.; Li, Wenhui; Partridge, G.B.; Hulet, R.G.; Rice Quantum Institute
    We study the role of particle transport and evaporation on the phase separation of an ultracold, spin-polarized atomic Fermi gas. We show that the previously observed deformation of the superfluid paired core is a result of evaporative depolarization of the superfluid due to a combination of enhanced evaporation at the center of the trap and the inhibition of spin transport at the normal-superfluid phase boundary. These factors contribute to a nonequilibrium jump in the chemical potentials at the phase boundary. Once formed, the deformed state is highly metastable, persisting for times of up to 2ﾠs.
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    Molecular Probe of Pairing in the BEC-BCS Crossover
    (American Physical Society, 2005) Partridge, G.B.; Strecker, K.E.; Kamar, R.I.; Jack, M.W.; Hulet, R.G.; Rice Quantum Institute
    We have used optical molecular spectroscopy to probe the many-body state of paired L6i atoms near a broad Feshbach resonance. The optical probe projects pairs of atoms onto a vibrational level of an excited molecule. The rate of excitation enables a precise measurement of the closed-channel contribution to the paired state. This contribution is found to be quite small, supporting the concept of universality for the description of broad Feshbach resonances. The dynamics of the excitation provide clear evidence for pairing across the BEC-BCS crossover and into the weakly interacting BCS regime.