A Minimal Active-Particle Realization of Non-Hermitian Chern Bulk-Boundary Correspondence

We show that a minimal frustrated Vicsek–Kuramoto active-particle model realizes a non-Hermitian Chern bulk-boundary correspondence. Unlike previous field-level settings, the Chern structure here emerges from microscopic self-propelled particles with a Sakaguchi phase lag. Fourier truncation of the phase distribution gives a non-Hermitian hydrodynamic matrix whose isotropic spectrum compactifies the wave-number plane; away from singular phase-lag endpoints, the frustration parameter twists endpoint eigenvectors and generates nontrivial Chern sectors. Nonlinear saturation then makes the selected spectral flow visible under collision boundaries, where strip modes predict chiral edge transport in agreement with particle simulations.