Invited Talk: Designing order: many-body excited states in van der Waals superlattices and quasicrystals

 Crystals consist of atoms arranged periodically. In 1982, the discovery of quasicrystals—structures with long-range order but without periodicity—shocked the scientific community. Today, advances in two-dimensional materials allow us to design such order at will. By stacking two atomically thin semiconductor sheets and rotating them by a chosen angle, we can create either periodic moiré superlattices or aperiodic quasicrystals. In this talk, I will discuss examples of how simply twisting two semiconductor monolayers leads to strikingly different many-body excited states in moiré superlattices and quasicrystals.