In this paper a gauge theory is proposed for the two-band model of Chern insulators.Based on the so-calle't Hooft monopole model,a U(1)Maxwell electromagnetic sub-field is constructed from an SU(2)gauge field,from...In this paper a gauge theory is proposed for the two-band model of Chern insulators.Based on the so-calle't Hooft monopole model,a U(1)Maxwell electromagnetic sub-field is constructed from an SU(2)gauge field,from which arise two types of topological defects,monopoles and e2 merons.We focus on the topological number in the Hall conductance σ_(xy)=e^(2)/hC,where C is the Chern number.It is discovered that in the monopole case C is indeterminate,while in the meron case C takes different values,due to a varying on-site energy m.As a typical example,we apply this method to the square lattice and compute the winding numbers(topological charges)of the defects;the C-evaluations we obtain reproduce the results of the usual literature.Furthermore,based on the gauge theory we propose a new model to obtain the high Chern numbers|C|=2,4.展开更多
Optical topological quasiparticles with nontrivial topological textures,such as skyrmions and meron lattices,have attracted considerable attention due to their potential applications in high-dimensional optical data s...Optical topological quasiparticles with nontrivial topological textures,such as skyrmions and meron lattices,have attracted considerable attention due to their potential applications in high-dimensional optical data storage and communications.Most previous studies of optical topological quasiparticles have focused on the formation of topological structures in isotropic media,whereas in our work,we perform a comprehensive investigation into the formation,topological stability,and phase transitions of optical meron lattices at the metal/uniaxial crystal interface.Our theoretical studies show that by rotating the optical axis orientation of the uniaxial crystal,meron lattices constructed by electric-field vector undergo phase transitions from a topologically nontrivial to a topologically trivial state,whereas the skyrmion number of the spin meron lattices remains robust against such rotations.The findings offer new insights into the topological stability and phase transitions of topological quasiparticles under light–matter interactions and hold promise for applications in optical data storage,information encryption,and communications.展开更多
Topological band theory has conventionally been concerned with the topology of bands around a single gap. Only recently non-Abelian topologies that thrive on involving multiple gaps were studied, unveiling a new horiz...Topological band theory has conventionally been concerned with the topology of bands around a single gap. Only recently non-Abelian topologies that thrive on involving multiple gaps were studied, unveiling a new horizon in topological physics beyond the conventional paradigm. Here, we report on the first experimental realization of a topological Euler insulator phase with unique meronic characterization in an acoustic metamaterial. We demonstrate that this topological phase has several nontrivial features:First, the system cannot be described by conventional topological band theory, but has a nontrivial Euler class that captures the unconventional geometry of the Bloch bands in the Brillouin zone.Second, we uncover in theory and probe in experiments a meronic configuration of the bulk Bloch states for the first time. Third, using a detailed symmetry analysis, we show that the topological Euler insulator evolves from a non-Abelian topological semimetal phase via. the annihilation of Dirac points in pairs in one of the band gaps. With these nontrivial properties, we establish concretely an unconventional bulk-edge correspondence which is confirmed by directly measuring the edge states via. pump-probe techniques. Our work thus unveils a nontrivial topological Euler insulator phase with a unique meronic pattern and paves the way as a platform for non-Abelian topological phenomena.展开更多
基金The authors XL and ZC acknowledge the financial support from the Natural Science Foundation of Beijing Grant No.Z180007the National Science Foundation of China Grant No.11572005WH acknowledges the support from the National Science Foundation of China Grant No.11874003 and Grant No.51672018.
文摘In this paper a gauge theory is proposed for the two-band model of Chern insulators.Based on the so-calle't Hooft monopole model,a U(1)Maxwell electromagnetic sub-field is constructed from an SU(2)gauge field,from which arise two types of topological defects,monopoles and e2 merons.We focus on the topological number in the Hall conductance σ_(xy)=e^(2)/hC,where C is the Chern number.It is discovered that in the monopole case C is indeterminate,while in the meron case C takes different values,due to a varying on-site energy m.As a typical example,we apply this method to the square lattice and compute the winding numbers(topological charges)of the defects;the C-evaluations we obtain reproduce the results of the usual literature.Furthermore,based on the gauge theory we propose a new model to obtain the high Chern numbers|C|=2,4.
基金National Natural Science Foundation of China(12174266,92250304,61935013)Basic and Applied Basic Research Foundation of Guangdong Province(2020B0301030009)Research Team Cultivation Program of Shenzhen University(2023QNT014)。
文摘Optical topological quasiparticles with nontrivial topological textures,such as skyrmions and meron lattices,have attracted considerable attention due to their potential applications in high-dimensional optical data storage and communications.Most previous studies of optical topological quasiparticles have focused on the formation of topological structures in isotropic media,whereas in our work,we perform a comprehensive investigation into the formation,topological stability,and phase transitions of optical meron lattices at the metal/uniaxial crystal interface.Our theoretical studies show that by rotating the optical axis orientation of the uniaxial crystal,meron lattices constructed by electric-field vector undergo phase transitions from a topologically nontrivial to a topologically trivial state,whereas the skyrmion number of the spin meron lattices remains robust against such rotations.The findings offer new insights into the topological stability and phase transitions of topological quasiparticles under light–matter interactions and hold promise for applications in optical data storage,information encryption,and communications.
基金the National Key R&D Program of China (2022YFA1404400)the National Natural Science Foundation of China (12125504 and 12074281)+7 种基金the “Hundred Talents Program” of the Chinese Academy of Sciencesthe Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutionspartially funded by a Marie-Curie fellowship (101025315)financial support from the Swedish Research Council (Vetenskapsradet) (2021-04681)funding from a New Investigator Award,EPSRC grant EP/W00187X/1EPSRC ERC underwrite grant EP/X025829/1a Royal Society exchange grant IES/ R1/221060Trinity College,Cambridge。
文摘Topological band theory has conventionally been concerned with the topology of bands around a single gap. Only recently non-Abelian topologies that thrive on involving multiple gaps were studied, unveiling a new horizon in topological physics beyond the conventional paradigm. Here, we report on the first experimental realization of a topological Euler insulator phase with unique meronic characterization in an acoustic metamaterial. We demonstrate that this topological phase has several nontrivial features:First, the system cannot be described by conventional topological band theory, but has a nontrivial Euler class that captures the unconventional geometry of the Bloch bands in the Brillouin zone.Second, we uncover in theory and probe in experiments a meronic configuration of the bulk Bloch states for the first time. Third, using a detailed symmetry analysis, we show that the topological Euler insulator evolves from a non-Abelian topological semimetal phase via. the annihilation of Dirac points in pairs in one of the band gaps. With these nontrivial properties, we establish concretely an unconventional bulk-edge correspondence which is confirmed by directly measuring the edge states via. pump-probe techniques. Our work thus unveils a nontrivial topological Euler insulator phase with a unique meronic pattern and paves the way as a platform for non-Abelian topological phenomena.
