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We demonstrate valley-dependent vortex generation in photonic graphene. Without breaking inversion symmetry, the excitation of two valleys leads to the formation of an optical vortex upon Bragg reflection to the third equivalent valley, with its chirality determined by the valley degree of freedom. Vortex-antivortex pairs with valley-dependent topological charge flipping are also observed and corroborated by numerical simulations. Furthermore, we develop a three-band effective Hamiltonian model to describe the dynamics of the coupled valleys and find that the commonly used two-band model is not sufficient to explain the observed vortex degeneracy lifting. Such valley-polarized vortex states arise from high-band excitation without a synthetic-field-induced gap opening. Our results from a photonic setting may provide insight for the study of valley contrasting and Berry-phase-mediated topological phenomena in other systems.
This article was published in the following journal.
Name: Physical review letters
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The primary purpose of the study is to determine if Seneca Valley Virus may be administered safely to patients with certain types of advanced cancer.
The purpose of this study is to find out how, why, and when Rift Valley Fever (RVF) spreads. Participants will be 250 adults and children, aged 1 year and older, from the Ijara District, K...
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Infection with a fungus of the genus COCCIDIOIDES, endemic to the SOUTHWESTERN UNITED STATES. It is sometimes called valley fever but should not be confused with RIFT VALLEY FEVER. Infection is caused by inhalation of airborne, fungal particles known as arthroconidia, a form of FUNGAL SPORES. A primary form is an acute, benign, self-limited respiratory infection. A secondary form is a virulent, severe, chronic, progressive granulomatous disease with systemic involvement. It can be detected by use of COCCIDIOIDIN.
Moving or bringing something from a lower level to a higher one. The concept encompasses biomechanic stresses resulting from work done in transferring objects from one plane to another as well as the effects of varying techniques of patient handling and transfer.
The geographic area of the Mekong Valley in general or when the specific country or countries are not indicated. Usually includes Cambodia, Indochina, and Laos.
An overuse injury causing lateral knee pain that results from repetitive friction of the iliotibial band over the lateral femoral epicondyle.
An acute infection caused by the RIFT VALLEY FEVER VIRUS, an RNA arthropod-borne virus, affecting domestic animals and humans. In animals, symptoms include HEPATITIS; abortion (ABORTION, VETERINARY); and DEATH. In humans, symptoms range from those of a flu-like disease to hemorrhagic fever, ENCEPHALITIS, or BLINDNESS.