Antiferromagnetism with Ultracold Atoms (Prof. R. Hulet)

Progress, however, has been stymied by an inability to cool to sufficiently low temperatures. In this talk, I will present our experimental results on the characterization of the three-dimensional Hubbard model near half-filling, realized using two spin-states of fermionic atomic lithium (6Li). We have developed a compensated optical lattice that has enabled, for the first time, the achievement of temperatures that are below the tunneling energy in the lattice, t. For strong interactions we observe the emergence of a density plateau and a reduction of the compressibility, indicative of the formation of a Mott insulator. The Hubbard model is known to exhibit antiferromagnetism at temperatures below the Néel temperature TN. We have detected antiferromagnetic correlations by spin-sensitive Bragg scattering of light. With improved cooling, it may be possible to resolve the open question of whether the Hubbard model contains the necessary ingredients to describe high-temperature superconductivity.