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Fractal photonic topological insulators
Tobias Biesenthal1, Lukas J Maczewsky1, Zhaoju Yang2
1Institut für Physik, Universität Rostock, Albert-Einstein-Straße 23, 18059 Rostock, Germany.
Science (New York, N.Y.)
|May 13, 2022
Summary
Researchers demonstrate fractal topological insulators without insulating bulk, proving the existence of protected edge states in novel fractal photonic lattices. This expands the understanding of topological matter and introduces topological fractals.
Area of Science:
- Condensed Matter Physics
- Photonics
- Materials Science
Background:
- Topological insulators are states of matter with scatter-free edge states and an insulating bulk.
- The insulating bulk is traditionally considered essential for defining topological properties.
Purpose of the Study:
- To investigate fractal topological insulators composed solely of edge sites.
- To experimentally verify the existence of topologically protected edge states in systems lacking bulk bands.
Main Methods:
- Fabrication and study of photonic lattices using helical waveguides arranged in fractal patterns.
- Experimental observation of light transport and chiral edge states.
Main Results:
- Experimental proof of topologically protected chiral edge states in fractal topological insulators without bulk bands.
- Observed enhanced light transport velocities in the topological fractal system compared to honeycomb lattices.
Conclusions:
- The insulating bulk is not essential for topological protection in all systems.
- Findings challenge conventional bulk-boundary correspondence, opening new avenues for topological fractals and expanded perceptions of topological insulators.
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