Erratum: Enhanced sensitivity at higher-order exceptional points.

This corrects the article DOI: 10.1038/nature23280.

Enhanced sensitivity at higher-order exceptional points.

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 with the environment. They correspond to points in parameter space at which the eigenvalues of the underlying system and the corresponding eigenvectors simultaneously coalesce. In optics, the abrupt nature of the phase transitions that are encountered around exceptional points has been shown to lead to many intriguing phenomena, such as loss-induced transparency, unidirectional invisibility, band merging, topological chirality and laser mode selectivity.

Scalar wave scattering in spherical cavity resonator with conical channels.

We study the scalar wave scattering off the spherical cavity resonator with two finite-length conical channels attached. We use the boundary wall method to explore the response of the system to changes in control parameters, such as the size of the structure and the angular width of the input and output channels, as well as their relative angular position. We found that the system is more sensitive to changes in the input channel, and a standing wave phase distribution occurs within the cavity for nontransmitting values of the incident wave number.

Generation of arbitrary complex quasi-non-diffracting optical patterns.

Due to their unique ability to maintain an intensity distribution upon propagation, non-diffracting light fields are used extensively in various areas of science, including optical tweezers, nonlinear optics and quantum optics, in applications where complex transverse field distributions are required. However, the number and type of rigorously non-diffracting beams is severely limited because their symmetry is dictated by one of the coordinate system where the Helmholtz equation governing beam propagation is separable. Here, we demonstrate a powerful technique that allows the generation of a rich variety of quasi-non-diffracting optical beams featuring nearly arbitrary intensity distributions in the transverse plane.

Tunneling phenomena in the open elliptic quantum billiard.

The study of open quantum billiards has gained popularity in the last decades, including different common and uncommon geometries such as the circular and stadium billiards. We present an extensive analysis of the elliptic quantum billiard with hyperbolic channels. We concentrate on the tunneling through an elliptic resonator-like structure.

Diffraction of plane waves by finite-radius spiral phase plates of integer and fractional topological charge.

A detailed analysis of the plane-wave diffraction by a finite-radius circular spiral phase plate (SPP) with integer and fractional topological charge and with variable transmission coefficients inside and outside of the plate edge is presented. We characterize the effect of varying the transmission coefficients and the parameters of the SPP on the propagated field. The vortex structure for integer and fractional phase step of the SPPs with and without phase apodization at the plate edge is also analyzed.