JQI

Abstract: In this talk, I will present a theory of interaction-induced band-flattening in strongly correlated electron systems. I will begin by illustrating an inherent connection between flat bands and index theorems and presenting a generic prescription for constructing flat bands by periodically repeating local Hamiltonians with topological zero modes. Specifically, a Dirac particle in an external, spatially periodic magnetic field can be cast in this form.

Abstract: Optical experiments utilize excitons (electron-hole bound states) in moiré transition metal dichalcogenide bilayers as a quantum simulator of the Bose-Hubbard model. Nevertheless, we show that these excitations possess nonbosonic commutation relations due to their composite nature, limiting the size of phase space for them to occupy. Such an effect manifests at weak electron-hole correlation, and restricts the number of excitons to be less than 4 per site and valley for three different bilayers.