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Ideal acoustic quantum spin Hall phase in a multi-topology platform
Xiao-Chen Sun1,2, Hao Chen1, Hua-Shan Lai1
1National Laboratory of Solid State Microstructures & Department of Materials Science and Engineering, Nanjing University, Nanjing, 210093, China.
Nature Communications
|February 22, 2023
Summary
We demonstrate an ideal acoustic quantum spin Hall (QSH) material with gapless helical edge states. This breakthrough enables robust broadband topological slow waves and compact topological devices.
Area of Science:
- Acoustic topological materials
- Condensed matter physics
- Quantum spin Hall effect
Background:
- Fermionic quantum spin Hall (QSH) materials possess gapless helical edge states protected by time-reversal symmetry.
- Bosonic counterparts typically exhibit gapped edge states at boundaries due to symmetry reduction, limiting their practical applications.
Purpose of the Study:
- To demonstrate an ideal acoustic quantum spin Hall (QSH) system with gapless edge states.
- To explore the potential for broadband topological slow waves and compact topological devices.
Main Methods:
- Constructing a global time-reversal symmetry (Tf) in both bulk and boundary of bilayer acoustic structures.
- Utilizing coupled resonators to engineer edge state behavior.
Main Results:
- Achieved gapless helical edge states in an acoustic QSH system by implementing global Tf.
- Observed edge states robustly winding multiple times within the first Brillouin zone.
- Identified the ideal QSH phase as a topological phase transition plane connecting trivial and higher-order topological phases.
Conclusions:
- The developed acoustic QSH platform offers robust gapless helical edge states.
- This system enables the creation of broadband topological slow waves and compact topological devices like lasers.
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