Ort: Kleiner Seminarraum 269, Appelstraße 2
Zeit: 10:15 Uhr
Abstract
Non-Hermitian phenomena offer a novel approach to analyze and interpret spectra in the presence of interactions: The one-particle Green's function may show "exceptional points" with a corresponding Fermi arc at zero frequency. They result from the non-Hermiticity of the effective Hamiltonian due to the presence of the self-energy and are topologically robust. The minimal model to observe this feature is a 1D Hubbard chain with unequal and alternating values of U at finite temperature. We prove the existence of exceptional points for this model using the density-matrix renormalization group (DMRG). This illustrates a case where temperature has a strong effect in 1D beyond the simple broadening of spectral features. An open question is the understanding of exceptional points in the two-particle Green's function.
