Magic angles are a hot topic in condensed matter physics: when two sheets of graphene are twisted by those angles the resulting material is superconducting.
Föreläsare: Jens Wittsten
Jens Wittsten will present a very simple operator whose spectral properties are thought to determine which angles are magical. It comes from a recent Physical Review Letter by Tarnopolsky–Kruchkov–Vishwanath. The mathematics behind this is a blend of representation theory (of the Heisenberg group in characteristic three), Jacobi theta functions and spectral instability of non-self-adjoint operators (involving Hörmander’s bracket condition in a simple setting). The results will be illustrated by colourful numerics which suggest some open problems. This is joint work with S. Becker, M. Embree, and M. Zworski.