Interface states in space-time photonic crystals: Topological origin, propagation and amplification
Studying the topology of spatio temporal media poses a fundamental challenge: their remarkable properties stem from breaking spatial and temporal symmetries, yet this same breaking obscures their topological characterization. Here, we show that space-time symmetries persist in crystals with travelin...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2026 |
| País: | España |
| Institución: | Universidad Autónoma de Madrid |
| Repositorio: | Biblos-e Archivo. Repositorio Institucional de la UAM |
| Idioma: | inglés |
| OAI Identifier: | oai:dnet:biblosearchi::40c6bfa415de72afbc075f9501fdb1db |
| Acceso en línea: | https://hdl.handle.net/10486/771020 https://dx.doi.org/10.1021/acsphotonics.5c02806 |
| Access Level: | acceso abierto |
| Palabra clave: | time-varying media topological photonics space-tim ephotonic crystals interface states Física |
| Sumario: | Studying the topology of spatio temporal media poses a fundamental challenge: their remarkable properties stem from breaking spatial and temporal symmetries, yet this same breaking obscures their topological characterization. Here, we show that space-time symmetries persist in crystals with traveling-wave modulations whose velocities can be either lower (subluminal) or higher (superluminal) than the speed of light, enabling the study of their topological properties and the prediction of spatio temporal interface states. For each modulation regime, we use a Lorentz transformation to a frame in which the modulation depends on only one of the transformed variables. Then, we identify a conserved joint parity time-reversal symmetry in the new variables that enforces the quantization of a spatio temporal Zak phase, elevating it to a Z2 topological invariant. Finally, we calculate the associated interface states and uncover unique features arising from time-varying effects, including selective directional amplification, propagation along subluminal and superluminal boundaries, frequency- and momentum-converted replicas, and broadband amplification even in the absence of momentum gaps. Our framework holds for spatio temporal modulations of any velocity, providing a unified description that encompasses photonic time crystals and clarifies their topological origin |
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