Browsing by Author "Hitchcock, J.M."

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    All-optical production of a lithium quantum gas using narrow-line laser cooling
    (American Physical Society, 2011) Duarte, P.M.; Hart, R.A.; Hitchcock, J.M.; Corcovilos, T.A.; Yang, T.-L.; Reed, A.; Hulet, R.G.; Rice Quantum Institute
    We have used the narrow 2S1/2→3P3/2 transition in the ultraviolet (uv) to laser cool and magneto-optically trap (MOT) 6Li atoms. Laser cooling of lithium is usually performed on the 2S1/2→2P3/2 (D2) transition, and temperatures of ∼300 μK are typically achieved. The linewidth of the uv transition is seven times narrower than the D2 line, resulting in lower laser cooling temperatures. We demonstrate that a MOT operating on the uv transition reaches temperatures as low as 59 μK. Furthermore, we find that the light shift of the uv transition in an optical dipole trap at 1070 nm is small and blueshifted, facilitating efficient loading from the uv MOT. Evaporative cooling of a two spin-state mixture of 6Li in the optical trap produces a quantum degenerate Fermi gas with 3×10˄6 atoms in a total cycle time of only 11 s.
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    Detecting antiferromagnetism of atoms in an optical lattice via optical Bragg scattering
    (American Physical Society, 2010) Corcovilos, T.A.; Baur, S.K.; Hitchcock, J.M.; Mueller, E.J.; Hulet, R.G.
    Antiferromagnetism of ultracold fermions in an optical lattice can be detected by Bragg diffraction of light, in analogy to the diffraction of neutrons from solid-state materials. A finite sublattice magnetization will lead to a Bragg peak from the (1/2 1/2 1/2) crystal plane with an intensity depending on details of the atomic states, the frequency and polarization of the probe beam, the direction and magnitude of the sublattice magnetization, and the finite optical density of the sample. Accounting for these effects we make quantitative predictions about the scattering intensity and find that with experimentally feasible parameters the signal can be readily measured with a CCD camera or a photodiode and used to detect antiferromagnetic order.
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    Dissipative transport of a Bose-Einstein condensate
    (American Physical Society, 2010) Dries, D.; Pollack, S.E.; Hitchcock, J.M.; Hulet, R.G.; Rice Quantum Institute
    We investigate the effects of impurities, either correlated disorder or a single Gaussian defect, on the collective dipole motion of a Bose-Einstein condensate of Li7 in an optical trap. We find that this motion is damped at a rate dependent on the impurity strength, condensate center-of-mass velocity, and interatomic interactions. Damping in the Thomas-Fermi regime depends universally on the disordered potential strength scaled to the condensate chemical potential and the condensate velocity scaled to the speed of sound. The damping rate is comparatively small in the weakly interacting regime, and, in this case, is accompanied by strong condensate fragmentation. In situ and time-of-flight images of the atomic cloud provide evidence that this fragmentation is driven by dark soliton formation.