Dresden 2020 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 19: Nonequilibrium Quantum Many-Body Systems 1 (joint session TT/DY)

DY 19.7: Talk

Tuesday, March 17, 2020, 11:00–11:15, HSZ 204

Exceptional points and the topology of quantum many-body spectra — •David Luitz and Francesco Piazza — Max Planck Institute for the Physics of Complex Systems, Dresden, Germany

We show that in a generic, ergodic quantum many-body system the interactions induce a nontrivial topology for an arbitrarily small non-Hermitian component of the Hamiltonian. This is due to an exponential-in-system-size proliferation of exceptional points which have the Hermitian limit as an accumulation (hyper)surface. The nearest-neighbor level repulsion characterizing Hermitian ergodic many-body systems is thus shown to be a projection of a richer phenomenology, where actually all the exponentially many eigenvalues are pairwise connected in a topologically robust fashion via exceptional points.