Universal spectral moment theorem and its applications in non-Hermitian systems

Abstract

The high sensitivity of the spectrum and wavefunctions to boundary conditions, termed the non-Hermitian skin effect, represents a fundamental aspect of non-Hermitian systems. While it endows non-Hermitian systems with unprecedented physical properties, it presents notable obstacles in grasping universal properties that are robust against microscopic details and boundary conditions. In this Letter, we introduce a pivotal theorem: in the thermodynamic limit, for any non-Hermitian systems with finite-range interactions, all spectral moments are invariant quantities, independent of boundary conditions, posing strong constraints on the spectrum. Utilizing this invariance, we propose a new criterion for bulk dynamical phases based on experimentally observable features and applicable to any dimensions and any boundary conditions. Based on this criterion, we define the bulk dispersive-to-proliferative phase transition, which is distinct from the real-to-complex spectral transition and contrary to traditional expectations. We verify these findings in 1D and 2D lattice models.

8 Pages, 4 Figures

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Cited by in corpus (6)

• Algebraic non-Hermitian skin effect and generalized Fermi surface formula in arbitrary dimensions
• Non-Bloch Dirac Points and Phase Diagram in the Stacked Non-Hermitian SSH Model
• Theory for the spectral splitting exponent of exceptional points
• Walking on Archimedean Lattices: Insights from Bloch Band Theory
• Experimentally Probing Non-Hermitian Spectral Transition and Eigenstate Skewness
• 3D Topologically Polarized Elastic Metamaterials Enable Asymmetric Energy Isolation at Low Frequencies