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We develop an accelerated gradient descent algorithm on the Grassmann manifold to compute the subspace spanned by a number of leading eigenvectors of a symmetric positive semi-definite matrix. This has a constant cost per iteration and a…

Optimization and Control · Mathematics 2024-06-27 Foivos Alimisis , Simon Vary , Bart Vandereycken

Lobachewsky geometry simulates a medium with special constitutive relations. The situation is specified in quasi-cartesian coordinates (x,y,z). Exact solutions of the Maxwell equations in complex 3-vector form, extended to curved space…

Mathematical Physics · Physics 2011-09-02 E. M. Ovsiyuk , V. M. Red'kov

The propagation of electromagnetic waves in helical media with spatial dispersion is investigated. The general form of the permittivity tensor with spatial dispersion obeying the helical symmetry is derived. Its particular form describing…

Mesoscale and Nanoscale Physics · Physics 2025-03-03 P. O. Kazinski , P. S. Korolev

Magnetic materials host a wealth of nonlinear dynamics, textures, and topological defects. This is possible due to the competition between strong nonlinearity and dispersion that act at the atomic scale as well as long-range interactions.…

Mesoscale and Nanoscale Physics · Physics 2024-07-02 Kyle Rockwell , Joel Hirst , Thomas A. Ostler , Ezio Iacocca

This paper systematically develops the Schr\"odinger formalism that is valid also for gyrotropic media where the material weights $W = \left ( \begin{smallmatrix} \varepsilon & \chi \chi^* & \mu \end{smallmatrix} \right ) \neq \overline{W}$…

Optics · Physics 2018-09-26 Giuseppe De Nittis , Max Lein

We present a novel general framework to deal with forward and backward components of the electromagnetic field in axially-invariant nonlinear optical systems, which include those having any type of linear or nonlinear transverse…

The differential form of the Maxwell's equations was first derived based on an assumption that the media are stationary, which is the foundation for describing the electro-magnetic coupling behavior of a system. For a general case in which…

Classical Physics · Physics 2022-08-29 Zhong Lin Wang

We consider the singular semiclassical initial value problem for the phase space Schrodinger equation. We approximate semiclassical quantum evolution in phase space by analyzing initial states as superpositions of Gaussian wave packets and…

Mathematical Physics · Physics 2014-02-28 P. D. Karageorge , G. N. Makrakis

We study here the nonlinear Schrodinger Equation (NLS) as the first term in a sequence of approximations for an electromagnetic (EM) wave propagating according to the nonlinear Maxwell equations (NLM). The dielectric medium is assumed to be…

Mathematical Physics · Physics 2009-11-10 Anatoli Babin , Alexander Figotin

We present a procedure for the systematic estimation of the dispersion properties of linear discrete systems with periodic time-varying coefficients. The approach relies on the analysis of a single unit cell, making use of Bloch theorem…

Classical Physics · Physics 2017-08-23 Javier Vila , Raj Kumar Pal , Massimo Ruzzene , Giuseppe Trainiti

The advection-diffusion and wave equations are the fundamental equations governing any physical law and therefore arise in many areas of physics and astrophysics. For complex problems and geometries, only numerical simulations can give…

Computational Physics · Physics 2014-01-08 J. Pétri

This work investigates the propagation of electromagnetic waves in waveguides within static curved spacetimes. We develop a covariant formalism using Hertzian potentials to describe guided electromagnetic modes in spacetimes with metrics…

General Relativity and Quantum Cosmology · Physics 2024-07-03 Javier Blanco-Romero

This paper discusses the spectral collocation method for numerically solving nonlocal problems: one dimensional space fractional advection-diffusion equation; and two dimensional linear/nonlinear space fractional advection-diffusion…

Numerical Analysis · Mathematics 2014-01-30 WenYi Tian , Weihua Deng , Yujiang Wu

In this work, we apply a semi-Lagrangian spectral method for the Vlasov-Poisson system, previously designed for periodic Fourier discretizations, by implementing Legendre polynomials and Hermite functions in the approximation of the…

Numerical Analysis · Mathematics 2018-07-09 Lorella Fatone , Daniele Funaro , Gianmarco Manzini

The reaction-diffusion model can generate a wide variety of spatial patterns, which has been widely applied in chemistry, biology, and physics, even used to explain self-regulated pattern formation in the developing animal embryo. In this…

Numerical Analysis · Mathematics 2020-01-29 Hui Zhang , Xiaoyun Jiang , Fanhai Zeng , George Em Karniadakis

This paper introduces weighted finite difference methods for numerically solving dispersive evolution equations with solutions that are highly oscillatory in both space and time. We consider a semiclassically scaled cubic nonlinear…

Numerical Analysis · Mathematics 2025-08-22 Yanyan Shi , Christian Lubich

For an isotropic and homogeneous nonlinear left-handed materials, for which the effective medium approximation is valid, Maxwell's equations for electric and magnetic fields lead naturally, within the slowly varying envelope approximation,…

Pattern Formation and Solitons · Physics 2010-03-09 N. Lazarides , G. P. Tsironis

We construct an explicit solution of the Cauchy initial value problem for the n-dimensional Schroedinger equation with certain time-dependent Hamiltonian operator of a modified oscillator. The dynamical SU(1,1) symmetry of the harmonic…

Mathematical Physics · Physics 2009-11-13 Maria Meiler , Ricardo Cordero-Soto , Sergei K. Suslov

The radiative transport equation accurately describes light transport in participating media such as biological tissues, though analytic solutions are known only for simple geometries. We present a pseudospectral technique to efficiently…

Computational Physics · Physics 2019-03-19 Samuel Powell , Ben T. Cox , Simon R. Arridge

This work concerns the analysis of electromagnetic dispersive media modelled by generalized Lorentz models. More precisely, this paper is the second of two articles dedicated to the long time behaviour of solutions of Maxwell's equations in…

Mathematical Physics · Physics 2024-10-08 Maxence Cassier , Patrick Joly , Luis Alejandro Rosas Martínez