PhD candidate Luca Donini

Ultracold bosons in the flat band of an optical kagome lattice

The kagome lattice hosts a flat band resulting from extensive geometric frustration. For fermions, this makes the kagome antiferromagnet a candidate for studying the quantum spin liquid phase. But even for weakly-interacting scalar bosons, the many-body physics in a flat band is complex and not fully understood. Stable loading of ultracold atoms into the flat band of an optical kagome is challenging, as it is not the ground band. For the first time, we load bosonic 39K atoms into the flat band of the kagome lattice using a negative absolute temperature scheme and achieve long lifetimes. I will report on our observations of the melting of the negative-temperature Mott Insulator into the flat band and on measurements characterising the resulting flat-band state.