APS Journals

Exceptional points, where eigenvalues and their eigenvectors coalesce (leading to defectiveness), are a defining feature of non-Hermitian systems. These papers chart their topology, from knot and braid invariants and no-go theorems to the realization of high-order exceptional points protected by symmetry, including an acoustic experiment that measures braid relations directly.

Under nonreciprocal or dissipative dynamics, bulk eigenstates can pile up at a boundary, the non-Hermitian skin effect. These papers span its detection and non-Bloch band theory, its experimental realization in topolectrical circuits, and its extensions to disordered, many-body, and chiral settings.

Non-Hermitian descriptions arise naturally from open quantum dynamics. The papers here link operator growth and Krylov complexity to dissipation, construct non-Hermitian pseudomodes for strongly coupled open systems, and unify Anderson localization transitions across Hermitian and non-Hermitian settings.

The extreme sensitivity of non-Hermitian spectra is both a resource and a challenge. These papers propose quantum-enhanced topological sensors, quantify the exponential sensitivity of spectra through pseudospectra, and characterize and manipulate scattering singularities in complex non-Hermitian media, and demonstrate parametric enhancement of sensor sensitivity at an exceptional point.