John Huckans

Three-body recombination in a three-state Fermi gas with widely tunable interactions.

We investigate the stability of a three spin state mixture of ultracold fermionic 6Li atoms over a range of magnetic fields encompassing three Feshbach resonances. For most field values, we attribute decay of the atomic population to three-body processes involving one atom from each spin state and find that the three-body loss coefficient varies by over 4 orders of magnitude. We observe high stability when at least two of the three scattering lengths are small, rapid loss near the Feshbach resonances, and two unexpected resonant loss features. At our highest fields, where all pairwise scattering lengths are approaching a_{t}=-2140a_{0}, we measure a three-body loss coefficient L_{3} approximately 5x10;{-22} cm;{6}/s and a trend toward lower decay rates for higher fields indicating that future studies of color superfluidity and trion formation in a SU(3) symmetric Fermi gas may be feasible.

Strongly Inhibited Transport of a Degenerate 1D Bose Gas in a Lattice

We report the observation of strongly damped dipole oscillations of a quantum degenerate 1D atomic Bose gas in a combined harmonic and optical lattice potential. Damping is significant for very shallow axial lattices (0.25 photon recoil energies), and increases dramatically with increasing lattice depth, such that the gas becomes nearly immobile for times an order of magnitude longer than the single-particle tunneling time. Surprisingly, we see no broadening of the atomic quasimomentum distribution after damped motion. Recent theoretical work suggests that quantum fluctuations can strongly damp dipole oscillations of a 1D atomic Bose gas, providing a possible explanation for our observations.

Evidence for an Excited-State Efimov Trimer in a Three-Component Fermi Gas

We observe enhanced three-body recombination in a three-component ;{6}Li Fermi gas attributable to an excited Efimov trimer state intersecting the three-atom scattering threshold near 895 G. From measurements of the recombination rate we determine the Efimov parameters kappa_{*} and eta_{*} for the universal region above 600 G which includes three overlapping Feshbach resonances. The value of kappa_{*} also predicts the locations of loss features previously observed near 130 and 500 G [T. B. Ottenstein, Phys. Rev. Lett. 101, 203202 (2008)10.1103/PhysRevLett.101.203202; J. H. Huckans, Phys. Rev. Lett. 102, 165302 (2009)10.1103/PhysRevLett.102.165302] suggesting they are associated with a ground-state Efimov trimer near threshold. We also report on the realization of a degenerate three-component Fermi gas with approximate SU(3) symmetry.

Dipolar atomic spin ensembles in a double-well potential

We experimentally study the spin dynamics of mesoscopic ensembles of ultracold magnetic spin-3 atoms located in two separated wells of an optical dipole trap. We use a radio-frequency sweep to selectively flip the spin of the atoms in one of the wells, which produces two separated spin domains of opposite polarization. We observe that these engineered spin domains are metastable with respect to the long-range magnetic dipolar interactions between the two ensembles. The absence of inter-cloud dipolar spin-exchange processes reveals a classical behavior, in contrast to previous results with atoms loaded in an optical lattice. When we merge the two subsystems, we observe spin-exchange dynamics due to contact interactions which enable the first determination of the s-wave scattering length of 52Cr atoms in the S=0 molecular channel a_0=13.5^{+11}_{-10.5}a_B (where a_B is the Bohr radius).

Double well potentials for atomic qubit gates in a designer optical lattice

Using four coherent laser beams we make two different 2D optical lattices with polarization-dependent periodicity. The lattices are coincident, and by shifting one with respect to the other, we create an array of double well potentials. We have designed a 2D optical lattice for /sup 87/Rb atoms consisting of an array of double well potentials. This lattice should allow us to test two-qubit gates and in general permit atomic control in support of nearest neighbor interaction physics such as the Ising model and quantum cellular automata.