Date Dec 16, 2020, 3:00 pm – 3:00 pm Location Zoom Seminar Zoom ID:940 8820 6070 passcode: 313103 Share on X Share on Facebook Share on LinkedIn Speaker Anton Kapustin Affiliation Caltech Details Event Description Building on the work of von Neumann and Wigner, M. Berry showed that there are topologically protected level-crossings in the space of quantum systems. These level-crossings can be detected using the curvature of the Berry connection. In this talk I will describe analogs of this for interacting lattice systems in infinite volume. Although the Berry connection is ill-defined for such systems, one can construct analogs of the Berry curvature on the parameter space which turn out to be closed form of degree d+2, where d is the dimension of the lattice. Integrals of these forms probe the non-trivial topology of the space of gapped lattice systems and can be used to detect topologically protected gapless points in the phase diagram. I will also explain the relation between higher Berry curvatures and the occurrence of topologically protected gapless edge modes in families of gapped lattice systems.