Topological edge states in a photonic Floquet insulator with unpaired Dirac cones  

作　　者：HUA ZHONG YAROSLAV VKARTASHOV YONGDONG LI MING LI YIQI ZHANG 

机构地区：[1]Key Laboratory for Physical Electronics and Devices,Ministry of Education,School of Electronic Science and Engineering,Xi’an Jiaotong University,Xi’an 710049,China [2]Institute of Spectroscopy,Russian Academy of Sciences,Moscow 108840,Russia [3]State Key Laboratory of Transient Optics and Photonics,Xi’an Institute of Optics and Precision Mechanics of Chinese Academy of Sciences,Xi’an 710119,China

出　　处：《Photonics Research》2024年第10期2078-2087,共10页光子学研究（英文版）

基　　金：Natural Science Basic Research Program of Shaanxi Province(2024JC-JCQN-06);National Natural Science Foundation of China(12074308,12304370);Fundamental Research Funds for the Central Universities(sxzy012024146);Research Project of the Institute of Spectroscopy of the Russian Academy of Sciences(FFUU-2024-0003)。

摘　　要：Topological insulators are most frequently constructed using lattices with specific degeneracies in their linear spectra,such as Dirac points.For a broad class of lattices,such as honeycomb ones,these points and associated Dirac cones generally appear in non-equivalent pairs.Simultaneous breakup of the time-reversal and inversion symmetry in systems based on such lattices may result in the formation of the unpaired Dirac cones in bulk spectrum,but the existence of topologically protected edge states in such structures remains an open problem.Here a photonic Floquet insulator on a honeycomb lattice with unpaired Dirac cones in its spectrum is introduced that can support unidirectional edge states appearing at the edge between two regions with opposite sublattice detuning.Topological properties of this system are characterized by the nonzero valley Chern number.Remarkably,edge states in this system can circumvent sharp corners without inter-valley scattering even though there is no total forbidden gap in the spectrum.Our results reveal unusual interplay between two different physical mechanisms of creation of topological edge states based on simultaneous breakup of different symmetries of the system.

关 键 词：spectrum DIRAC CONES 

分 类 号：O469[理学—凝聚态物理]