# Rubidium BEC in Variable Optical Lattices

Diffraction of BECs on optical lattices of variable spatial periodicity

The directed motion of atoms in a quantum ratchet is due to contributions of transporting Floquet eigenstates

(illustrated here as conveyor belts) with different mean velocities

Left: Illustration of the spatial variation of the band structure of the lattice along position z. At z=0 a topological edge state is expected. Right: Series of vertically binned images for different relative phases of the Raman state preparation beams. Maximum loading into the edge state is observed for a relative phase of π/2.

Ultracold atoms can be trapped in periodic optical potentials. The achieved systems, so called optical lattices, much resemble an artificial solid. We investigate the band structure of optical lattices of variable inversion symmetry, as a step towards simulating the diversity of potentials that nature provides us in the system of electrons in natural crystals. In our setup, optical potentials for atoms are generated by means of Fourier-synthesis. For a nearly sawtooth-like potential, we use the superposition of a usual standing wave lattice of spatial periodicity λ/2 with a novel multiphoton lattice of periodicity λ/4.

Fourier Synthesis of Conservative Atom Potentials

G. Ritt, C. Geckeler, T. Salger, G. Cennini, and M. Weitz

Phys. Rev. A

**74**, 063622 (2006)

Atomic Landau-Zener tunneling in Fourier-synthesized optical lattices

T. Salger, C. Geckeler, S. Kling, and M. Weitz

Phys. Rev. Lett.

**99**, 190405 (2007)

T. Salger, S. Kling, T. Hecking, C. Geckeler, L. Morales-Molina, and M. Weitz

Science

**326**, 1241 (2009),

__arXiv:0912.0102__

T. Salger, C. Grossert, S. Kling, and M. Weitz

Phys. Rev. Lett.

**107**, 240401 (2011), arXiv:1108.4447

M. Leder, C. Grossert, and M. Weitz

Nature Communications

**5**, 3327 (2014), arXiv:1402:3132

**7**, 10440 (2016), arXiv:1407.0605

**7**, 13112 (2016), arXiv:1604.02060

Quantenratsche für ultrakalte Atome

T. Salger and M. Weitz

Phys. Unserer Zeit

**41**, 110 (2010)