BACKGROUND Singularities are critical points for which the behavior of a mathematical
model governing a physical system is of a fundamentally different nature compared to the …

Non-Hermitian physical systems have attracted considerable attention lately for their
unconventional behaviour around exceptional points (EPs)—spectral singularities at which …

Recent years have seen a tremendous progress in the theory and experimental
implementations of non-Hermitian photonics, including all-lossy optical systems as well as …

In the past decade, the concept of parity-time $(\mathcal {PT}) $ symmetry, originally
introduced in non-Hermitian extensions of quantum mechanical theories, has come into …

Non-Hermitian degeneracies, also known as exceptional points, have recently emerged as
a new way to engineer the response of open physical systems, that is, those that interact …

In the past few years, concepts from non-Hermitian (NH) physics, originally developed within
the context of quantum field theories, have been successfully deployed over a wide range of …

Exploiting the interplay between gain, loss and the coupling strength between different
optical components creates a variety of new opportunities in photonics to generate, control …

Nearly one century after the birth of quantum mechanics, parity–time symmetry is
revolutionizing and extending quantum theories to include a unique family of non-Hermitian …

Recent studies on exceptional points (EPs) in non-Hermitian optical systems have revealed
unique traits, including unidirectional invisibility, chiral mode switching and laser self …

Exceptional points (EPs) are degeneracies of non-Hermitian operators where, in addition to
the eigenvalues, the corresponding eigenmodes become degenerate. Classical and …