Rostock 2019 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 12: Ultra-cold atoms, ions and BEC

A 12.28: Poster

Dienstag, 12. März 2019, 16:30–18:30, S Fobau Physik

Flat band physics in an optical kagome lattice — •Max Melchner — University of Cambridge, United Kingdom

We are currently building a cold-atom experiment to study ultracold atoms in an optical kagome lattice. In the tight-binding approximation, the three lowest motional bands of the kagome lattice are separated from higher-lying bands by a large energy gap. The third lowest energy band is analytically flat. We aim to populate the flat band with ultracold atoms, which should allow us to study effects that arise in strongly correlated many-body systems (e.g. the spin liquid state).

One of the major experimental challenges will be to stabilize the atomic cloud in the flat band of the kagome lattice. Since the flat band is not the lowest band, it will not be occupied by an ultracold atomic gas. There are two basic ways of occupying the flat band: Either one changes the sign of hopping, thereby inverting the band structure such that the flat band is the lowest, or one creates a stable population inversion. In the experiment we are building, we want to do the latter. By using attractive interactions in potassium, we intend to set an upper bound on energy, which will naturally lead to a negative temperature state.

With our experiment we will be able to study transport in a flat motional band. With the addition of interactions and the ability of switching between fermionic and bosonic atoms, we believe this to be an extremely versatile platform for research into single- and many-body localization as well as frustration effects and macroscopic degeneracy.