Vorträge in der Woche 23.03.2026 bis 29.03.2026

Freitag, 27.03.2026: Locality in Quantum Lattice Systems

Tom Wessel (Tübingen)

Locality is an important feature of quantum many-body systems, both from a physical perspective and as a feature that makes rigorous analysis possible. We consider locality properties of extended quantum lattice systems with local Hamiltonians, which play a central role in many-body quantum theory and quantum information theory. One of the key tools for analysing such systems are Lieb-Robinson bounds, which quantify how fast information can propagate under the time evolution generated by a local Hamiltonian. Although these bounds have been known since the seminal work of Lieb and Robinson in 1972, they gained renewed attention around 2005 when Hastings realized that they could be used to establish a variety of fundamental results, including rigorous statements about spectral properties of local Hamiltonians. Two very prominent results are decay of correlations and automorphic equivalence for gapped ground states, which are the foundation for many more results. But statements for thermal equilibrium states at positive temperature are also possible. In my thesis, I contributed to improving and generalizing Lieb-Robinson bounds, as well as to their applications. In this talk, I will provide a brief introduction to extended quantum lattice systems and then highlight two of my contributions: first, a Lieb-Robinson bound for a previously uncovered class of Hamiltonians, and second, an application of such bounds to the study of locality properties of Gibbs states.