QuMat seminar

Abstract:

In a variety of physical scenarios ranging from classical meta-materials to correlated quantum many-body systems, non-Hermitian (NH) Hamiltonians have proven to be a powerful and conceptually simple tool for effectively describing dissipation. Recently, investigating the topological properties of such NH systems has become a broad frontier of research.

In this talk, after giving a general introduction to the field, I will discuss how NH topological features such as stable exceptional degeneracies and a remarkable spectral sensitivity with respect to boundary conditions can emerge in the quasi-particle description of correlated electron systems that are globally
described by a Hermitian Hamiltonian. In particular, I will demonstrate how magnetic fluctuations at the onset of ferromagnetism may promote the symmetry-protected nodal surface states of a topological insulator to a NH Weyl phase that is robust against generic perturbations.

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