Braiding topology of symmetry-protected degeneracy points in non-Hermitian systems
 
                   
                   
                        
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Journal:
PHYSICAL REVIEW B 
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Abstract:
Degeneracy points in non-Hermitian systems are of great interest. While a homotopic framework exists for understanding their behavior in the absence of symmetry, it does not apply to symmetry-protected degeneracy points with reduced codimension. In this work, utilizing algebraic topology, we provide a systematic classification of these symmetry-protected degenerate points and investigate the braid conservation rule followed by them. Using a model Hamiltonian and circuit simulation, we discover that, contrary to simple annihilation, pairwise-created symmetry-protected degeneracy points merge into a higher-order degeneracy point, which goes beyond the abelian picture. Our findings empower researchers across diverse fields to uncover new phenomena and applications harnessing symmetry-protected non-Hermitian degeneracy points. 
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Indexed by:
Journal paper 
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Volume:
109 
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Issue:
4 
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Page Number:
L041102 
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Translation or Not:
no 
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Date of Publication:
2024-01-05 
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Links to published journals:
https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.L041102