Malte Rontgen

In Physics, we often rely on global symmetries, i.e., symmetries that commute with the Hamiltonian describing our setup. In realistic setups, however, such symmetries are usually broken and are valid only in subdomains of the full system: They become local, an example being finite lattices. Such local symmetries can also be present by design (i.e., without the artificial breaking of a global symmetry), and are therefore a much broader concept than global symmetries. Unfortunately, many tools for the treatment of symmetries in Physics rely on global symmetries (such as Bloch theory) and are not applicable to locally symmetric systems. In my research, I try to solve this discrepancy by developing tools for the treatment and understanding of locally symmetric systems.