Observation of antichiral edge states in a circuit lattice

Yang, Yuting; Zhu, Dejun; Hang, Zhi Hong; Chong, Yidong

doi:10.1007/s11433-021-1675-0

Cited by 47 publications

(21 citation statements)

References 44 publications

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“…Recently, electronic circuits were demonstrated to be an excellent platform to simulate topological band physics . Utilizing electronic components, including resistors, inductors, capacitors, and operational amplifiers, one can study abundant topological phenomena, such as (higher-order) topological insulators, − semimetals, − and non-Hermitian physics, − among others. − In this Letter, we report the realization of WTIs in a spinless 2D Su–Schrieffer–Heeger (SSH) circuit under centrosymmetric deformations. By evaluating the strong topological index ν 0 and two weak topological indexes ν 1 and ν 2 , we find a Dirac semimetal (DSM) phase (ν 0 = 1) and four WTI phases (ν 0 = 0 and ν 1 ν 2 = 11, 10, 01, 00).…”

Section: Introductionmentioning

confidence: 99%

Experimental Realization of Two-Dimensional Weak Topological Insulators

et al. 2022

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We report the experimental realization of a two-dimensional (2D) weak topological insulator (WTI) in spinless Su–Schrieffer–Heeger circuits with parity–time and chiral symmetries. Strong and weak topological indexes are adopted to explain the experimental findings that a Dirac semimetal (DSM) phase and four WTI phases emerge in turn when we modulate the centrosymmetric circuit deformations. In the DSM phase, it is found that the Dirac cone is highly anisotropic and that it is not pinned to any high-symmetry points but can widely move within the Brillouin zone, which eventually leads to the phase transition between WTIs. In addition, we observe a pair of flat-band domain wall states by designing spatially inhomogeneous node connections. Our work provides the first experimental evidence for 2D WTIs, which significantly advances our understanding of the strong and weak nature of topological insulators, the robustness of flat bands, and the itinerant and anisotropic features of Dirac cones.

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Section: Introductionmentioning

confidence: 99%

Experimental Realization of Two-Dimensional Weak Topological Insulators

et al. 2022

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“…Recently, a new type of edge state, known as the anti-chiral edge state, has been put forward, which can propagate in the same direction on opposite edges [ 13 ]. This interesting phenomenon was originally proposed in a so-called modified Haldane model and soon spread across many physical systems, for example, an exciton-polariton honeycomb lattice with strip geometry [ 14 ], a Heisenberg ferromagnet on the honeycomb lattice [ 15 ], a gyromagnetic photonic crystal (PC) [ 16 , 17 ], circuit lattices [ 18 ], and acoustics systems [ 19 ]. It has broad potential applications in integrated photonic devices such as non-reciprocal transmission.…”

Section: Introductionmentioning

confidence: 99%

Reconfigurable Light Imaging in Photonic Higher-Order Topological Insulators

et al. 2022

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Topological phases of matter with robust edge states have revolutionized the fundamental intuitions for wave control. The recent development of higher-order topological insulators (HOTIs) realizes even lower dimensional topological states that enable versatile wave manipulations (e.g., light imaging). However, in conventional HOTIs, the topological states are usually protected by certain crystalline symmetries and therefore bounded at specific locations, hindering their applications in modern digital ears, which often prefer tunability and reconfigurability. Here, we report the reconfigurable light imaging based on topological corner states and anti-chiral edge states in a two-dimensional (2D) photonic HOTI with a honeycomb lattice of yttrium iron garnet (YIG, a ferrite material) rods. Sublattices A and B are applied with magnetic fields in opposite directions, which realize the so-called modified Haldane model that hosts anti-chiral edge modes. By further breaking the lattice’s inversion symmetry via adjusting the radii of A and B rods, topological edge states with valley degrees of freedom emerge, which not only exhibit valley-dependence but also surprisingly show anti-chiral behaviors. In the valley edge gap, which is of nontrivial higher-order topology, corner states appear. With different combinations of corner states and anti-chiral edge states, versatile reconfigurable light imaging can be realized. As examples, a multiplexing waveguide-resonator device, a pine tree imaging that can be lit up or put out at will and selective imaging for partial objects in a two-heart pattern are demonstrated. The proposed HOTI shows high potential in future intelligent devices with exciting tunable and reconfigurable functions, which may inspire a wide range of applications such as topological switching, imaging processing, and nonreciprocal integrated photonics.

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“…Their topological properties and robustness are investigated by calculating local Chern number and disordered transmission function. Since the antichiral edge states are recently achieved in the photonic system [43] and electric system [44], it is expected our proposed model can also be realized in the near future with the same experimental technique.…”

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confidence: 98%

“…This interesting phenomenon has also been theoretically investigated in many other physical systems, for example, an exciton-polariton honeycomb lattice with strip geometry [36], a Heisenberg ferromagnet on the honeycomb lattice [37], and a graphene nanoribbon with zigzag edges under a uniform uniaxial strain [38], etc [39][40][41][42]. More importantly, the existence of antichiral edge states based on this modified Haldane model has been experimentally demonstrated in gyromagnetic photonic crystal system [43] and classical circuit lattice [44]. It is found that the robust propagation of antichiral edge states topologically protected by the winding number depends on the corner shape in the open boundary condition [43].…”

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confidence: 99%

Anti-chiral edge states and hinge states based on the Haldane model

Cheng,

Chen,

Zhang

et al. 2021

Preprint

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Different from the chiral edge states, antichiral edge states propagating in the same direction on the opposite edges are theoretically proposed based on the modified Haldane model, which is recently experimentally realized in photonic crystal and electric lattice systems. Here, we instead present that the antichiral edge states in the two-dimensional system can also be achieved based on the original Haldane model by combining two subsystems with the opposite chirality. Most importantly, by stacking these two-dimensional systems into three-dimension, it is found that the copropagating antichiral hinge states localized on the two opposite diagonal hinge cases of the system can be implemented. Interestingly, the location of antichiral hinge states can be tuned via hopping parameters along the third dimension. By investigating the local Chern number/layer Chern number and transmission against random disorders, we confirm that the proposed antichiral edge states and hinge states are topologically protected and robust against disorders. Our proposed model systems are expected to be realized in photonic crystal and electric lattice systems.

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Observation of antichiral edge states in a circuit lattice

Cited by 47 publications

References 44 publications

Experimental Realization of Two-Dimensional Weak Topological Insulators

Experimental Realization of Two-Dimensional Weak Topological Insulators

Reconfigurable Light Imaging in Photonic Higher-Order Topological Insulators

Anti-chiral edge states and hinge states based on the Haldane model

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