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arXiv · 2106.11987

Fourth-Order Exceptional Points in Correlated Quantum Many-Body Systems

Lorenzo Crippa·Jan Carl Budich·Giorgio Sangiovanni
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Abstract

Non-Hermtian (NH) Hamiltonians effectively describing the physics of dissipative systems have become an important tool with applications ranging from classical meta-materials to quantum many-body systems. Exceptional points, the NH counterpart of spectral degeneracies, are among the paramount phenomena unique to the NH realm. While realizations of second-order exceptional points have been reported in a variety of microscopic models, higher-order ones have largely remained elusive in the many-body context, as they in general require fine tuning in high-dimensional parameter spaces. Here, we propose a microscopic model of correlated fermions in three spatial dimensions and demonstrate the occurrence of interaction-induced fourth-order exceptional points that are protected by chiral symmetry. We demonstrate their stability against symmetry breaking perturbations and investigate their characteristic analytical and topological properties.

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Lorenzo Crippa, Jan Carl Budich, Giorgio Sangiovanni. 2021-06-22. Fourth-Order Exceptional Points in Correlated Quantum Many-Body Systems. https://doi.org/10.1103/physrevb.104.l121109

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