We show that the combined action of diffraction and convection (walk-off) in wave mixing processes leads to a nonlinear symmetry breaking in the generated traveling waves. The dynamics near to threshold is reduced to a Ginzburg-Landau model, showing an original dependence of the nonlinear self-coupling term on the convection. Analytical expressions of the intensity and velocity of traveling waves emphasize the utmost importance of convection in this phenomenon. These predictions are in excellent agreement with the numerical solutions of the full dynamical model.
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http://dx.doi.org/10.1103/PhysRevE.72.025603 | DOI Listing |
Quantum materials governed by emergent topological fermions have become a cornerstone of physics. Dirac fermions in graphene form the basis for moiré quantum matter and Dirac fermions in magnetic topological insulators enabled the discovery of the quantum anomalous Hall (QAH) effect. By contrast, there are few materials whose electromagnetic response is dominated by emergent Weyl fermions.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Department of Physics, School of Physical Science and Engineering, Beijing Jiaotong University, Beijing 100044, China.
Two-dimensional (2D) materials with spontaneous polarization can exhibit large second-order nonlinear optical (NLO) effects. Here, we present a series of stable distorted monolayers by using first-principles calculations and lattice vibration analysis. The structural distortion leads to a lower polar symmetry, giving rise to intrinsic ferroelectricity with a Curie point up to room temperature.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario, Canada M5S 3H6.
The cost of encoding a system Hamiltonian in a digital quantum computer as a linear combination of unitaries (LCU) grows with the 1-norm of the LCU expansion. The Block Invariant Symmetry Shift (BLISS) technique reduces this 1-norm by modifying the Hamiltonian action on only the undesired electron-number subspaces. Previously, BLISS required a computationally expensive nonlinear optimization that was not guaranteed to find the global minimum.
View Article and Find Full Text PDFDiscov Nano
January 2025
Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049, Madrid, Spain.
Chemically tuned organic-inorganic hybrid halide perovskites based on bromide and chloride anions CH(NH)Pb(BrCl) (CH(NH): formamidinium ion, FA) have been crystallized and investigated by neutron powder diffraction (NPD), single crystal X-ray diffraction (SCXRD), scanning electron microscopy (SEM) and UV-vis spectroscopy. FAPbBr and FAPbCl experience successive phase transitions upon cooling, lowering the symmetry from cubic to orthorhombic phases; however, these transitions are not observed for the mixed halide phases, probably due to compositional disorder. The band-gap engineering brought about by the chemical doping of FAPb (BrCl) perovskites (x = 0.
View Article and Find Full Text PDFLight Sci Appl
January 2025
Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware, 19716, USA.
Exceptional points (EPs) have been extensively explored in mechanical, acoustic, plasmonic, and photonic systems. However, little is known about the role of EPs in tailoring the dynamic tunability of optical devices. A specific type of EPs known as chiral EPs has recently attracted much attention for controlling the flow of light and for building sensors with better responsivity.
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