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

• URL: http://arxiv.org/abs/2106.11987v1
• Date: Tue, 22 Jun 2021 18:00:06 GMT
• Title: Fourth-Order Exceptional Points in Correlated Quantum Many-Body Systems
• Authors: Lorenzo Crippa, Jan Carl Budich and Giorgio Sangiovanni
• Abstract summary: Non-Hermtian (NH) Hamiltonians 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. We propose a microscopic model of correlated fermions in three spatial dimensions and demonstrate the occurrence of interaction-induced fourth-order exceptional points.
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• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• 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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