Vortex dynamics in coherent ensembles of exciton polaritons (condensates) is studied in the framework of the polarization-dependent Gross-Pitaevskii equation. Vortex lattices can be resonantly excited in the polariton field by the interference of three or more optical pumps. Vortex-antivortex pairs can also appear in polariton condensates due to scattering with disorder. The nonlinear vortex dynamics is characterized by interactions of vortex cores and vortex-antivortex recombination.
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http://dx.doi.org/10.1103/PhysRevLett.101.187401 | DOI Listing |
Sci Rep
December 2024
School of Physics, IISER Thiruvananthapuram, Vithura, Kerala, 695551, India.
This work reports magnetic field direction dependent second magnetisation peak (SMP) anomaly in single crystals of oxygenated [Formula: see text] for [Formula: see text] ab. Detailed investigations on crystal A revealed the direction dependence of SMP anomaly at temperatures below 25 K, above which the direction dependence vanishes. The state of spatial order of the vortex lattice was found to be correlated to the vortex lattice symmetry that underwent a change at certain fields and was captured via single flux jumps observed in the third and fifth quadrant of magnetisation hysteresis loops.
View Article and Find Full Text PDFScience
December 2024
Department of Electrical and Computer Engineering, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore.
The structural periodicity in photonic crystals guarantees the crystal's effective energy band structure, which is the fundamental cornerstone of topological and moiré physics. However, the shear modulus in most fluids is close to zero, which makes it challenging for fluids to maintain spatial periodicity akin to photonic crystals. We realized periodic vortices in hydrodynamic metamaterials and created a bilayer moiré superlattice by stacking and twisting two such vortex fluids.
View Article and Find Full Text PDFPhys Rev E
November 2024
Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China.
We investigate synchronization behaviors of a Kuramoto oscillator network with a two-dimensional square-lattice configuration. We show that the oscillator network can reach a phase-locking vortex synchronized state in the long time limit starting from random initial oscillator phases sampled according to the von Mises distribution characterized by a zero mean and a finite concentration parameter. We further reveal that the stability of the vortex synchronized state is sensitive to the presence of local node defects, in contrast to the usual knowledge that oscillator networks should exhibit robustness against local perturbations.
View Article and Find Full Text PDFMoiré metasurfaces exhibit high optical tuneabilities and versatile light manipulation capabilities. Both infinite quality factor (Q factor) and topological vortex configurations in momentum space (-space) of the bound state in the continuum (BIC) have introduced new dimensions for light modulation. Herein, we propose a moiré metasurface comprising two identical square photonic lattices superimposed with a commensurate angle of 12.
View Article and Find Full Text PDFNanophotonics
September 2024
Departamento de Física and Centro de Física Teórica e Computacional, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Ed. C8, Lisboa 1749-016, Portugal.
Flat-band periodic materials are characterized by a linear spectrum containing at least one band where the propagation constant remains nearly constant irrespective of the Bloch momentum across the Brillouin zone. These materials provide a unique platform for investigating phenomena related to light localization. Meantime, the interaction between flat-band physics and nonlinearity in continuous systems remains largely unexplored, particularly in continuous systems where the band flatness deviates slightly from zero, in contrast to simplified discrete systems with exactly flat bands.
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