Correlations in non-Hermitian systems and Diagram techniques for the steady state

Abstract

We describe a diagrammatic technique for non-Hermitian fermionic systems that is applicable in the steady state, and which allows addressing correlations effects by systematic expansion. Applying this method to exceptional points or rings, we find that nodal objects in non-Hermitian systems are generically displaced in momentum-space due to interactions. This in turn can be connected to the fact that exceptional points invariably break a class of orthonormal symmetries that are generally present for nodal points in Hermitian systems, and which protect the integrity of the node at low energy scales.

4 pages

References in corpus (6)

• The physics of exceptional points
• Dirac materials
• Weyl Exceptional Rings in a Three-Dimensional Dissipative Cold Atomic Gas
• Periodic Table for Topological Bands with Non-Hermitian Bernard-LeClair Symmetries
• Flat Band in Disorder Driven Non-Hermitian Weyl Semimetals
• Interacting non-Hermitian ultracold atoms in a harmonic trap: Two-body exact solution and high-order exceptional point