Metal–Dielectric Polarization-Preserving Anisotropic Mirror for Chiral Optical Tamm State

This numerical study demonstrates the possibility of exciting a chiral optical Tamm state localized at the interface between a cholesteric liquid crystal and a polarization-preserving anisotropic mirror conjugated to a metasurface. The difference of the proposed structure from a fully dielectric one is that the metasurface makes it possible to decrease the number of layers of a polarization-preserving anisotropic mirror by a factor of more than two at the retained Q-factor of the localized state. It is shown that the proposed structure can be used in a vertically emitting laser.

Hyperchaos in a Bose-Hubbard Chain with Rydberg-Dressed Interactions

We study the chaos and hyperchaos of Rydberg-dressed Bose–Einstein condensates (BECs) in a one-dimensional optical lattice. Due to the long-range, soft-core interaction between the dressed atoms, the dynamics of the BECs are described by the extended Bose-Hubbard model. In the mean-field regime, we analyze the dynamical stability of the BEC by focusing on the ground state and localized state configurations. Lyapunov exponents of the two configurations are calculated by varying the soft-core interaction strength, potential bias, and length of the lattice. Both configurations can have multiple positive Lyapunov exponents, exhibiting hyperchaotic dynamics. We show the dependence of the number of the positive Lyapunov exponents and the largest Lyapunov exponent on the length of the optical lattice. The largest Lyapunov exponent is directly proportional to areas of phase space encompassed by the associated Poincaré sections. We demonstrate that linear and hysteresis quenches of the lattice potential and the dressed interaction lead to distinct dynamics due to the chaos and hyperchaos. Our work is relevant to current research on chaos as well as collective and emergent nonlinear dynamics of BECs with long-range interactions.

Signatures of Quantum Interference in the Time Dependence of Charge Transfer in Donor–Bridge–Acceptor Molecules

Numerical solution of the time-dependent Schrödinger equation is combined with a statistical procedure for analyzing the time-dependent probability density to look for signatures of quantum phase interference in charge transfer across two donor–bridge–acceptor molecules. The results show a strong dependence of transfer time on relative phase in an initially localized state. Additionally, the transfer time shows a stronger dependence on molecular symmetry for asymmetric initial localizations than symmetric initial localizations.

Optical and structure properties of CH3NH3PbI3 perovskite films doped with Cesium

Doped methylammonium lead iodide (MAPbI3) solar cells with cesium (Cs) (MA1-xCsxPbI3, x=0, 0.03, 0.05, 0.1) thin films were prepared with and without chlorobenzene (CB). The change in the crystallinity of the formed films upon doping with Cs was studied using an X–Ray diffraction technique. The Rietveld refinement method applying MADU software was used to reveal the effect of Cs and CB on the lattice parameters, crystallite size, strain and dislocation of the formed films. CB reduced the number of pinholes and the grain size in the formed films as compared with the corresponding films prepared without CB. The UV-Vis-NIR spectroscopy technique was used to investigate the transmittance, reflectance and absorbance spectra for Cs doped MAPbI3 with and without CB. At 500 nm, the MAPbI3 thin film prepared without CB has the highest transmittance as compared with other thin films. The reflectance of the Cs doped samples prepared with CB is higher than for the samples prepared without CB. In the visible range, the absorbance has the highest values in 5% Cs (without CB) and 10% Cs (with CB) doped samples. The changes in the refractive index depend on the amount of Cs doping and the samples prepared with and without CB. The direct optical band gap of all films is affected by the crystallite size and the formed localized state created inside the bend. Samples prepared with CB have a higher optical conductivity than the corresponding samples prepared without CB. The influence of Cs doping and CB addition on the photoluminescence (PL) emitted spectra was studied using a PL set-up with a laser source of 532 nm.

A Simple Method to Differentiate between Free-Carrier Recombination and Trapping Centers in the Bandgap of the p-Type Semiconductor

In this research, the ranges of the localized states in which the recombination and the trapping rates of free carriers dominate the entire transition rates of free carriers in the bandgap of the p-type semiconductor are described. Applying the Shockley–Read–Hall model to a p-type material under a low injection level, the expressions for the recombination rates, the trapping rates, and the excess carrier lifetimes (recombination and trapping) were described as functions of the localized state energies. Next, the very important quantities called the excess carriers’ trapping ratios were described as functions of the localized state energies. Variations of the magnitudes of the excess carriers’ trapping ratios with the localized state energies enable us to categorize the localized states in the bandgap as the recombination, the trapping, the acceptor, and the donor levels. Effects of the majority and the minority carriers’ trapping on the excess carrier lifetimes are also evaluated at different localized energy levels. The obtained results reveal that only excess minority trapping affects the excess carrier lifetimes, and excess majority carrier trapping has no effect.

Quadrature protection of squeezed states in a one-dimensional photonic topological insulator

What is the role of topology in the propagation of quantum light in photonic lattices? We address this question by studying the propagation of squeezed states in a topological one-dimensional waveguide array, benchmarking our results with those for a topologically trivial localized state, and studying their robustness against disorder. Specifically, we study photon statistics, one-mode and two-mode squeezing, and entanglement generation when the localized state is excited with squeezed light. These quantum properties inherit the shape of the localized state but, more interestingly, and unlike in the topologically trivial case, we find that propagation of squeezed light in a topologically protected state robustly preserves the phase of the squeezed quadrature as the system evolves. We show how this latter topological advantage can be harnessed for quantum information protocols.

Observation of domain wall bimerons in chiral magnets

Topological defects embedded in or combined with domain walls have been proposed in various systems, some of which are referred to as domain wall skyrmions or domain wall bimerons. However, the experimental observation of such topological defects remains an ongoing challenge. Here, using Lorentz transmission electron microscopy, we report the experimental discovery of domain wall bimerons in chiral magnet Co-Zn-Mn(110) thin films. By applying a magnetic field, multidomain structures develop, and simultaneously, chained or isolated bimerons arise as the localized state between the domains with the opposite in-plane components of net magnetization. The multidomain formation is attributed to magnetic anisotropy and dipolar interaction, and domain wall bimerons are stabilized by the Dzyaloshinskii-Moriya interaction. In addition, micromagnetic simulations show that domain wall bimerons appear for a wide range of conditions in chiral magnets with cubic magnetic anisotropy. Our results promote further study in various fields of physics.