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Light scattering from chiral plasmonic structures can create near fields with an asymmetry greater than the equivalent circularly polarised light, a property sometimes referred to as superchirality. These near fields with enhanced chiral…

Exceptional points (EPs) are special parameter values of a non-Hermitian eigenvalue problem where eigenfunctions corresponding to a multiple eigenvalue coalesce. In optics, EPs are associated with a number of counter-intuitive wave…

Optics · Physics 2019-10-08 Amgad Abdrabou , Ya Yan Lu

In this thesis we address a series of new problems in non-hermitian optical scattering with increasing degrees of complexity. We develop the theory of reflectionless scattering modes, introducing a novel and broad class of impedance-matched…

Optics · Physics 2020-12-10 William R. Sweeney

Scattering experiments with microwave cavities were performed and the effects of broken time-reversal invariance (TRI), induced by means of a magnetized ferrite placed inside the cavity, on an isolated doublet of nearly degenerate…

Chaotic Dynamics · Physics 2014-05-07 S. Bittner , B. Dietz , H. L. Harney , M. Miski-Oglu , A. Richter , F. Schäfer

Exceptional points(EPs), branch points of complex energy surfaces at which eigenvalues and eigenvectors coalesce, are ubiquitous in non-Hermitian systems. Many novel properties and applications have been proposed around the EPs. One of the…

We experimentally study the propagation of circularly polarized light in the sub-diffusion regime by exploiting enhanced backscattering (EBS, also known as coherent backscattering) of light under low spatial coherence illumination. We…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Young L. Kim , Prabhakar Pradhan , Min H. Kim , Vadim Backman

We demonstrate that electric-dipole scatterers can mimic chiral light-matter interaction by generating far-field circular polarization upon scattering, even though the optical chirality of the incident field as well as that of the scattered…

Optics · Physics 2019-06-12 Sergey Nechayev , Peter Banzer

Bound states in the continuum (BICs) and exceptional points (EPs), as two distinct physical singularities represented by complex frequencies in non-Hermitian systems, have garnered significant attention and clear definitions in their…

We report two types of singularities that arise from fluctuations during the formation of charge- or spin-density waves. The first is the exceptional point (EP), corresponding to a higher-order pole of the retarded Green's function. Such…

Mesoscale and Nanoscale Physics · Physics 2025-12-01 Zixi Fang , Chen Fang

Exceptional points (EPs) are singularities of energy levels in non-Hermitian systems. In this Letter, we demonstrate the surface of EPs on a magnon polariton platform composed of coupled magnons and microwave photons. Our experiments show…

Mesoscale and Nanoscale Physics · Physics 2019-12-11 Xufeng Zhang , Kun Ding , Dafei Jin , Xianjing Zhou , Jing Xu

We demonstrate the existence of exceptional points of degeneracy (EPD) of periodic eigenstates in non-Hermitian coupled chains of dipolar scatterers. Guided modes supported by these structures can exhibit an EPD in their dispersion diagram…

Optics · Physics 2017-03-22 Mohamed A. K. Othman , Vincenzo Galdi , Filippo Capolino

Coherent backscattering is a multiple scattering interference effect which enhances the diffuse reflection off a disordered sample in the backward direction. Classically, the enhanced intensity is twice the average background under well…

Resonance coupling in non-Hermitian systems can lead to exotic features, such as bound states in the continuum (BICs) and exceptional points (EPs), which have been widely employed to control the propagation and scattering of light. Yet,…

Optics · Physics 2022-04-01 Zi-Lan Deng , Feng-Jun Li , Huanan Li , Xiangping Li , Andrea Alù

We exploit low spatial coherence illumination to dephase time-reversed partial waves outside its finite coherence area, which virtually creates a controllable coherence volume and isolates the minimal number of scattering events from higher…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Young L. Kim , Prabhakar Pradhan , Hariharan Subramanian , Yang Liu , Min H. Kim , Vadim Backman

The backscattering of circularly polarized light at normal incidence to a half-space of scattering particles is studied using the Electric Field Monte Carlo (EMC) method. The spatial distribution of the backscattered light intensity is…

Optics · Physics 2009-11-11 Kevin G. Phillips , Min Xu , S. K. Gayen , R. R. Alfano

Non-Hermitian systems have attracted much interest in recent decades, driven partly by the existence of exotic spectral singularities, known as exceptional points (EPs), where the dimensionality of the system evolution operator is reduced.…

We present a combined classical and quantum electrodynamics description of the coupling between two circularly-polarized quantum emitters held above a metal surface supporting surface plasmons. Depending on their position and their natural…

Mesoscale and Nanoscale Physics · Physics 2019-02-11 C. A. Downing , J. C. López Carreño , F. P. Laussy , E. del Valle , A. I. Fernández-Domínguez

Non-Hermitian degeneracies, also known as exceptional points (EPs), have been the focus of much attention due to their singular eigenvalue surface structure. Nevertheless, as pertaining to a non-Hermitian metasurface platform, the reduction…

Non-Hermitian systems and their topological singularities, such as exceptional points (EPs), lines, and surfaces, have recently attracted intense interest. The investigation of these exceptional constituents has led to fruitful…

Optics · Physics 2024-08-08 Liang Fang , Kai Bai , Cheng Guo , Tian-Rui Liu , Jia-Zheng Li , Meng Xiao

We investigate exceptional points of degeneracy (EPDs) in electromagnetic scattering of a sphere dimer from the electroquasistatic limit to the fully retarded regime. In the quasistatic limit, we prove that $\parity\trev$-symmetric…

Optics · Physics 2026-05-29 Emanuele Corsaro , Filippo Capolino , Carlo Forestiere