Abstract:

Abstract: Cold atoms in periodic potentials are versatile quantum systems for implementing simple models prevalent in condensed matter theory. Here we realize the 2D Bose-Hubbard model by loading a Bose-Einstein condensate into an optical lattice, and study the resulting Mott insulator. The measured momentum distributions agree quantitatively with theory (no adjustable parameters). In these systems, the Mott insulator forms in a spatially discrete shell structure which we probe by focusing on correlations in atom shot noise. These correlations show a marked dependence on the lattice depth, consistent with the changing size of the insulating shell expected from simple arguments. 

Reference: I. B. Spielman, W. D. Phillips, and J.V. Porto, Phys. Rev. Lett. 98, 080404 (2007).

Abstract: Optical dipole traps and atom chips are two very powerful tools for the quantum manipulation of neutral atoms. We demonstrate that both methods can be combined by creating an optical lattice potential on an atom chip. A red-detuned laser beam is retroreflected using the atom chip surface as a high-quality mirror, generating a vertical array of purely optical oblate traps. We transfer thermal atoms from the chip into the lattice and observe cooling into the two-dimensional regime. Using a chip-generated Bose–Einstein condensate, we demonstrate coherent Bloch oscillations in the lattice.

Reference: D. Gallego, S. Hofferberth, T. Schumm, P. Krüger, and J. Schmiedmayer, Opt. Lett. 34, 3463 (2009).

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