Article
Optics
Glen J. Kissel
Summary: Anderson localization simulations in one-dimensional disordered optical systems often focus on the localization length or its inverse, with less emphasis on the calculation of the density of states. This paper modifies a technique originally used for calculating the integrated density of states for one-dimensional disordered crystals to be applicable to randomly layered optical media. The density of states can then be easily obtained through differentiation. The algorithm is demonstrated on one-dimensional quarter-wave stack and non-quarter-wave stack models with disordered layer thicknesses.
Article
Materials Science, Multidisciplinary
Ba Phi Nguyen, Duy Khuong Phung, Kihong Kim
Summary: We numerically investigate the time evolution of wave packets in one-dimensional semi-infinite lattices with mosaic modulated random on-site potentials. We find that the long-time behavior of the time-dependent reflectance obeys a power law, indicating the onset of Anderson localization or classical diffusion. The phenomena of delocalization occur at certain discrete values of the central energy and depend on the modulation period. We provide an analytical formula for the quasiresonance energies and explain the delocalization phenomenon based on the interplay between randomness and band structure. The states at the quasiresonance energies are found to be critical states through finite-size scaling analysis.
Article
Acoustics
M. Colvez, R. Cottereau
Summary: This paper focuses on the modeling of elastic wave propagation at small incidence angles through a randomly-fluctuating horizontally-layered slab. The model takes into account the coupling of quasi-P and quasi-S waves by establishing a coordinate system following the coherent front. The transmission and reflection coefficients of the slab are estimated by solving a set of coupled stochastic ordinary differential equations.
Article
Optics
Sebastian Weidemann, Mark Kremer, Stefano Longhi, Alexander Szameit
Summary: Anderson's groundbreaking discovery of sudden breakdown of conductivity due to stochastic imperfections in a crystal revolutionized our understanding of disordered media and stimulated decades of studies. Recent research has shed new light on disordered media with dissipation, suggesting that dissipation can affect spectral localization and wave spreading in ways not previously observed.
Article
Optics
G. Dujardin, A. Armaroli, S. Rota Nodari, A. Mussot, A. Kudlinski, S. Trillo, M. Conforti, S. De Bievre
Summary: This study investigates the modulational instability in optical fibers with random group-velocity dispersion generated by sharply localized perturbations, either randomly or periodically placed along the fiber. The results show that low-frequency MI side lobes may appear and grow with the strength of the perturbations, but they are affected by the randomness in their position. Comparisons between randomly perturbed fibers and periodically perturbed fibers with finite average value perturbations reveal how randomness in strength of the variations and randomness in position can influence the Arnold tongues differently.
Article
Materials Science, Multidisciplinary
Flavio Noronha, Jose A. S. Lourenco, Tommaso Macri
Summary: This study investigates the emergence of the quantum boomerang effect (QBE) in non-Hermitian systems and emphasizes the importance of symmetries of the Hamiltonian and the initial state. The results show that even in the case of complex spectrum, a boomerang-like behavior can occur in a non-Hermitian system.
Article
Physics, Multidisciplinary
Benjamin Nagler, Martin Will, Silvia Hiebel, Sian Barbosa, Jennifer Koch, Michael Fleischhauer, Artur Widera
Summary: We experimentally study the dissipative dynamics of ultracold bosonic gases in a dynamic disorder potential with tunable correlation time. Our results reveal the interplay between superfluidity and time-dependent disorder and establish ultracold atoms as a platform for studying spatiotemporal noise and time-dependent disorder.
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
Zixuan Gao, Zhenli Xu, Zhiguo Yang, Fangwei Ye
Summary: A research team proposes an accurate algorithm for the eigenproblems of aperiodic systems, allowing exploration of energy bands in fully aperiodic systems. The relationship between the intensity of the aperiodic potential and the localization-to-delocalization transition is observed, and a Pythagoras superposition principle for localized eigenstates of two-dimensional moire lattices is revealed. This principle sheds light on exploring the physics of localizations for moire lattices.
Article
Physics, Multidisciplinary
Benjamin Apffel, Sander Wildeman, Antonin Eddi, Emmanuel Fort
Summary: In this study, we investigate and implement the temporal analog in time disordered systems. We introduce randomly distributed temporal interfaces to a spatially homogeneous medium to create a temporal structure. The observed wave field is the result of interference between reflected and refracted waves on the interfaces. The growth of waves exponentially depends on the disorder level, similar to the evolution model in spatial cases. The relative position of the momentum gap in time modulated systems plays a crucial role in wave field evolution. By compensating for damping with tuned excitation, localized transient waves appear on the liquid surface, resulting from a specific history of multiple interferences.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Antton Goicoechea, John H. Page, Sergey E. Skipetrov
Summary: The study found that in an ensemble of resonant point scatterers embedded in an anisotropic background medium, localized modes have anisotropic spatial shapes, but their anisotropy is weaker than expected from purely geometric considerations. The modes with the longest lifetimes are the most anisotropic, and their anisotropy increases with the size of the disordered medium.
Article
Physics, Fluids & Plasmas
Lima Biswas, Priyanka Shukla
Summary: Resonant triad interactions were investigated in a stably stratified shear flow, analyzing the secondary terms produced by the interaction of two primary modes and solving the differential equations for spatial amplitudes. Self-resonating modes were identified using dispersion curves.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Physics, Fluids & Plasmas
Lima Biswas, Priyanka Shukla
Summary: This study investigates the temporal evolution of internal waves forming a resonant triad in a two-dimensional inviscid stably stratified uniform shear flow. It derives amplitude equations, equilibrium solutions, and conducts linear stability analysis around equilibrium solutions for various interaction cases. Numerical solutions for different local Richardson numbers are also presented.
PHYSICAL REVIEW FLUIDS
(2021)
Article
Astronomy & Astrophysics
Anna Tkachenko, Vladimir Krasnoselskikh, Andrii Voshchepynets
Summary: This paper describes a theoretical model of harmonic emissions of type III solar radio bursts. The model considers nonlinear coupling of Langmuir waves in the solar wind plasma and proposes two mechanisms for generating harmonic emissions in quasihomogeneous and inhomogeneous plasma. The results suggest that harmonic emissions from quasihomogeneous plasma are more intense.
ASTROPHYSICAL JOURNAL
(2021)
Article
Engineering, Electrical & Electronic
Sanghoon Kim, Aobo Li, Jiyeon Lee, Daniel F. Sievenpiper
Summary: The article introduces a novel metamaterial surface that actively tunes its resonance frequency to absorb electromagnetic waves, achieving a self-tuning function. Experimental results confirm the performance of the metamaterial surface and the increase in absorption frequency range, demonstrating high practical value.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2021)
Article
Engineering, Electrical & Electronic
Scott Stewart, Tom J. Smy, Shulabh Gupta
Summary: In this paper, a ray optical methodology based on the UTD is proposed to model electromagnetic field scattering from curved metasurfaces. The approach utilizes the generalized sheet transition conditions to characterize the surface in terms of susceptibility dyadics, and a ray optics description is developed for the scattered fields including specular geometrical optical field, surface diffraction, and a transition region over the shadow boundary.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2022)
Article
Physics, Multidisciplinary
Ba Phi Nguyen, Duy Khuong Phung, Kihong Kim
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2020)
Article
Physics, Multidisciplinary
Seulong Kim, Kihong Kim
Summary: In this theoretical study, mode conversion and resonant absorption of high-frequency electromagnetic waves into longitudinal modes in magnetized and stratified plasmas are investigated. It is found that mode conversion only occurs for extraordinary waves, and the mode conversion coefficient can be close to one in certain parameter ranges. The results suggest strong asymmetry under sign changes of the incident angle and external magnetic field, with implications for plasma heating phenomena.
JOURNAL OF THE KOREAN PHYSICAL SOCIETY
(2021)
Editorial Material
Communication
Kihong Kim
Editorial Material
Communication
Kihong Kim
Editorial Material
Communication
Kihong Kim
Editorial Material
Communication
Kihong Kim
Article
Mechanics
Seulong Kim, Kihong Kim
Summary: In this paper, we theoretically study mode conversion and resonant overreflection of magnetohydrodynamic waves in an inhomogeneous plane-stratified plasma with the presence of a nonuniform shear flow. By using precise numerical calculations, we find that there can be a giant overreflection where the reflectance is much larger than 10 under certain conditions. The overreflection occurs in a fairly broad range of incident angles, frequency, and plasma beta, and its mechanism is explained in terms of the formation of inhomogeneous and open cavities close to the resonances.
Editorial Material
Communication
Kihong Kim
Article
Materials Science, Multidisciplinary
Ba Phi Nguyen, Duy Khuong Phung, Kihong Kim
Summary: We numerically investigate the time evolution of wave packets in one-dimensional semi-infinite lattices with mosaic modulated random on-site potentials. We find that the long-time behavior of the time-dependent reflectance obeys a power law, indicating the onset of Anderson localization or classical diffusion. The phenomena of delocalization occur at certain discrete values of the central energy and depend on the modulation period. We provide an analytical formula for the quasiresonance energies and explain the delocalization phenomenon based on the interplay between randomness and band structure. The states at the quasiresonance energies are found to be critical states through finite-size scaling analysis.
Article
Materials Science, Multidisciplinary
Kihong Kim, Seulong Kim
Summary: Based on the presented research and calculations, we find that mode conversion of transverse electromagnetic waves into longitudinal oscillations and the associated resonant absorption of wave energy also occur in electronic and photonic systems when there is an inhomogeneous potential or medium parameter. This phenomenon behaves similarly to the mode conversion and resonant absorption observed in p-polarized electromagnetic waves in an unmagnetized plasma.
Article
Materials Science, Multidisciplinary
Seulong Kim, Kihong Kim
Article
Communication
Kihong Kim
Article
Materials Science, Multidisciplinary
Seulong Kim, Kihong Kim
Article
Communication
Kihong Kim, Yeonok Chung
Article
Materials Science, Multidisciplinary
Seulong Kim, Kihong Kim
