Article
Chemistry, Multidisciplinary
Huanhuan Yang, Lingling Song, Yunshan Cao, Peng Yan
Summary: We experimentally realized a 2D weak topological insulator in spinless Su-Schrieffer-Heeger circuits with parity-time and chiral symmetries. By modulating centrosymmetric circuit deformations, we observed a Dirac semimetal phase and four weak topological insulator phases. Our work provides the first experimental evidence for 2D weak topological insulators and advances our understanding of topological insulators, flat bands, and the features of Dirac cones.
Article
Quantum Science & Technology
Zidong Lin, Lin Zhang, Xinyue Long, Yu-ang Fan, Yishan Li, Kai Tang, Jun Li, XinFang Nie, Tao Xin, Xiong-Jun Liu, Dawei Lu
Summary: In this experiment, we perform a quantum simulation of the two-dimensional non-Hermitian quantum anomalous Hall model using a nuclear magnetic resonance processor. We develop a stochastic average approach based on the stochastic Schrodinger equation to realize the non-Hermitian dissipative quantum dynamics. The experiment demonstrates the stability of dynamical topology against weak noise and observes two types of dynamical topological transitions driven by strong noise, as well as a region where the emergent topology is always robust regardless of the noise strength.
NPJ QUANTUM INFORMATION
(2022)
Article
Multidisciplinary Sciences
Qinghua Guo, Tianshu Jiang, Ruo-Yang Zhang, Lei Zhang, Zhao-Qing Zhang, Biao Yang, Shuang Zhang, C. T. Chan
Summary: Experimental observation of non-Abelian topological charges and edge states in a PT-symmetric transmission line network, along with the discovery of a non-Abelian quotient relation for the bulk-edge correspondence. This new topological property opens up possibilities for intriguing observable phenomena in the field of material science.
Article
Physics, Applied
Hongqing Dai, Linbo Liu, Baizhan Xia, Dejie Yu
Summary: Acoustic tweezers with excellent biological compatibility have been developed based on topologically protected phononic modes, enabling noncontact label-free microparticle manipulations at an on-chip level.
PHYSICAL REVIEW APPLIED
(2021)
Article
Multidisciplinary Sciences
Weiyuan Tang, Kun Ding, Guancong Ma
Summary: In this study, non-Abelian state permutations are experimentally demonstrated in a non-Hermitian system. The eigenstates in this system can evolve across different manifolds, corresponding to state permutation. By encircling exceptional arcs, five non-trivial permutations are achieved, indicating the existence of non-Abelian groups in non-Hermitian systems.
NATIONAL SCIENCE REVIEW
(2022)
Article
Materials Science, Multidisciplinary
Zhenxing Cui, Mian Peng, Xuewei Zhang, Qiang Wei, Mou Yan, Gang Chen
Summary: In this paper, the authors experimentally observe the existence of multiple acoustic topological boundary states in four band gaps, including end states in one-dimensional phononic crystals and corner states in two-dimensional phononic crystals, based on acoustic quartic-root topological insulators. These boundary states originate from two consecutive square-root procedures, similar to square-root topological insulators. The paper provides a simple approach to achieve multiple boundary states by inserting additional cavities, without the need for elaborate structure designing, making acoustic manipulation more flexible.
Article
Physics, Multidisciplinary
Bin Jiang, Adrien Bouhon, Zhi-Kang Lin, Xiaoxi Zhou, Bo Hou, Feng Li, Robert-Jan Slager, Jian-Hua Jiang
Summary: The research explores non-Abelian band topology in acoustic semimetals using a tunable kagome model, demonstrating topological transitions induced by controlling the geometry of metamaterials and the braiding of different band nodes. The study reveals the underlying rules for the conversion and transfer of non-Abelian topological charges in multiple bandgaps, providing insights for studies on multi-band topological semimetals and out-of-equilibrium systems.
Article
Materials Science, Multidisciplinary
Yi Yang, Hoi Chun Po, Vincent Liu, John D. Joannopoulos, Liang Fu, Marin Soljacic
Summary: The emergence of nonsymmorphic chiral symmetries in the Hofstadter model is theoretically studied, which are introduced through synthetic symmetries in synthetic gauge fields. Depending on the values of the gauge fields, the nonsymmorphic chiral symmetries can exhibit non-Abelian algebra and protect fourfold degeneracy at all momenta. Moreover, the parity of the system size can determine whether the resulting insulating phase is trivial or topological.
Article
Multidisciplinary Sciences
Zhe Zhang, Pierre Delplace, Romain Fleury
Summary: Topological systems exhibit robustness against disorder and defects, with Chern insulators being the most reliable design currently. However, an anomalous non-reciprocal topological network has been identified to have superior robustness to edge transmission under arbitrarily large disorder levels. This discovery paves the way for efficient planar energy transport on 2D substrates with full protection against large fabrication flaws.
Article
Multidisciplinary Sciences
Midya Parto, Christian Leefmans, James Williams, Franco Nori, Alireza Marandi
Summary: The researchers demonstrate that photonic topological lattices with dissipative couplings can exhibit non-Abelian dynamics and geometric phases, contrasting with energy-conserving systems. Topology plays a central role in various fields, and its study has extended to open systems, leading to fascinating effects such as topological lasing and exceptional surfaces. They show that the geometric properties of Bloch eigenstates in dissipatively coupled lattices cannot be described by scalar Berry phases, unlike conservative Hamiltonians. This behavior is attributed to significant population exchanges among dissipation bands. The researchers provide theoretical and experimental evidence that such exchanges manifest as matrix-valued operators in Bloch dynamics, resulting in non-commuting pairs and non-Abelian dynamics in two-dimensional lattices.
NATURE COMMUNICATIONS
(2023)
Review
Nanoscience & Nanotechnology
Haoran Xue, Yihao Yang, Baile Zhang
Summary: Topological acoustics is an emerging field that explores the design and construction of artificial structures to manipulate sound waves using topological protection. Recent research has focused on exploring new topological concepts in physical systems. These developments demonstrate the importance of topological acoustic systems in advancing topological physics.
NATURE REVIEWS MATERIALS
(2022)
Article
Multidisciplinary Sciences
Tianyu Li, Haiping Hu
Summary: This study investigates topological insulators with multiple tangled gaps in Floquet settings and uncovers uncharted Floquet non-Abelian topological insulators without any static or Abelian analog. It reveals that the bulk-edge correspondence follows the multiplication rule of the quaternion group and demonstrates an exotic swap effect that is absent in Floquet Abelian systems. This work presents Floquet topological insulators characterized by non-Abelian charges and opens up possibilities for exploring non-equilibrium topological phases.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Applied
Xiaopei Sun, Bing Li, Enna Zhuo, Zhaozheng Lyu, Zhongqing Ji, Jie Fan, Xiaohui Song, Fanming Qu, Guangtong Liu, Jie Shen, Li Lu
Summary: A topological-insulator-nanowire-based transmon qubit was constructed and its strong coupling to a coplanar waveguide resonator was demonstrated. Flux-tunable spectrum and Rabi oscillations with a qubit lifetime T-1 of approximately 0.5 μs were observed. This hybrid platform, combining topological materials and quantum electrodynamic circuits, can be used to study physical properties such as Majorana zero modes in topological quantum circuits.
APPLIED PHYSICS LETTERS
(2023)
Article
Multidisciplinary Sciences
Deyuan Zou, Tian Chen, Wenjing He, Jiacheng Bao, Ching Hua Lee, Houjun Sun, Xiangdong Zhang
Summary: This work reports the experimental realizations of hybrid higher-order skin-topological effect in non-reciprocal topoelectrical circuits, showcasing the dynamic interplay of non-reciprocal pumping and topological localization to form various states. Through a highly versatile and scalable circuit platform, the authors demonstrate higher-order topological skin effects, paving the way for applications in topological switching and sensing.
NATURE COMMUNICATIONS
(2021)
Article
Materials Science, Multidisciplinary
Yen-Ta Huang, Dung-Hai Lee
Summary: Applying the method of bosonization, we derive the bosonized theory for free fermion topological insulators and superconductors with time reversal, charge conjugation, and flavor symmetries. We also present the theory of a class of bosonic symmetry-protected topological states.
Article
Physics, Multidisciplinary
Mudi Wang, Ruo-Yang Zhang, Lei Zhang, Dongyang Wang, Qinghua Guo, Zhao-Qing Zhang, C. T. Chan
Summary: By utilizing hetero-structures of photonic crystals, we have achieved large-area one-way transport with uniformly distributed one-way waveguide states, which can concentrate energy and are robust against defects and localization effects.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Ze-Guo Chen, Weiyuan Tang, Ruo-Yang Zhang, Zhaoxian Chen, Guancong Ma
Summary: This study explores the transfer of topological boundary states in an acoustic waveguide system and reveals the quantitative condition for the breakdown of adiabaticity. The results not only lay a foundation for future research on dynamic state transfer, but also inspire applications leveraging nonadiabatic transitions as a new degree of freedom.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Applied
Neng Wang, Ruo-Yang Zhang, C. T. Chan
Summary: Long-range and robust acoustic pulling can be achieved by using a pair of one-way chiral surface waves supported on the interface between two phononic crystals composed of spinning cylinders, overcoming limitations of traditional acoustic pulling methods.
PHYSICAL REVIEW APPLIED
(2021)
Article
Physics, Multidisciplinary
Ze-Guo Chen, Ruo-Yang Zhang, C. T. Chan, Guancong Ma
Summary: This study demonstrates the realization of non-Abelian braiding of multiple degenerate acoustic waveguide modes, exploring the dynamics and geometric phase variations. By switching the order of different braiding processes, the non-Abelian characteristics are revealed.
Article
Physics, Multidisciplinary
Mudi Wang, Shan Liu, Qiyun Ma, Ruo-Yang Zhang, Dongyang Wang, Qinghua Guo, Biao Yang, Manzhu Ke, Zhengyou Liu, C. T. Chan
Summary: In this study, we designed phononic crystals with earring nodal links and experimentally observed two different types of earring nodal links. The experimental evidence supports the unique phenomena of non-Abelian band topology.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Xiaohan Cui, Ruo-Yang Zhang, Zhao-Qing Zhang, C. T. Chan
Summary: This article presents a scheme to realize disorder-induced symmetry-protected topological phase transitions in two-dimensional photonic crystals, and demonstrates the manifestation of the topological properties through a new scattering approach.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Dongyang Wang, Biao Yang, Ruo-Yang Zhang, Wen-Jie Chen, Z. Q. Zhang, Shuang Zhang, C. T. Chan
Summary: Nodal lines in periodic systems, represented as loops in three-dimensional momentum space, possess rich topological features. This study introduces and demonstrates a novel type of photonic straight nodal lines protected by an unusual rotoinversion time symmetry in a D2D metacrystal. These nodal lines are located at the central axis and hinges of the Brillouin zone and are accompanied by topological surface states. The manipulation of frequency allows for the transition from closed to open equifrequency contours and the realization of diffractionless surface wave propagations, showing potential for the development of superimaging topological devices.
PHYSICAL REVIEW LETTERS
(2022)
Article
Multidisciplinary Sciences
Mudi Wang, Qiyun Ma, Shan Liu, Ruo-Yang Zhang, Lei Zhang, Manzhu Ke, Zhengyou Liu, C. T. Chan
Summary: Bulk and edge modes in topological materials are closely related, and chiral anomaly bulk states can be achieved by applying boundary conditions to a topologically trivial crystal. The most important property of topological materials is the robust transport of topological edge modes, which depends on bulk topological invariants.
NATURE COMMUNICATIONS
(2022)
Article
Multidisciplinary Sciences
Xiaoxiao Wu, Haiyan Fan, Tuo Liu, Zhongming Gu, Ruo-Yang Zhang, Jie Zhu, Xiang Zhang
Summary: This article reports an approach for topological phononics, utilizing the unique interplay of sound in different media. The authors demonstrate the realization of type-II nodal rings in a simple three-dimensional phononic crystal and experimentally observe strongly tilted drumhead surface states. This phononic approach opens up new possibilities for exploring topological physics in classical systems and designing high-performance acoustic devices.
NATURE COMMUNICATIONS
(2022)
Article
Multidisciplinary Sciences
Jie Peng, Ruo-Yang Zhang, Shiqi Jia, Wei Liu, Shubo Wang
Summary: The central idea of metamaterials and metaoptics is to use the geometry of structures to achieve exotic optical functionalities. In this study, the researchers discovered that the topology of metal structures determines the topological properties of optical fields and offers a new dimension for optical functionalities independent of specific materials or structures. By mapping polarization singularities (PSs) to non-Hermitian exceptional points and using homotopy theory, they extracted the core invariant and conservation law that govern the topological classification and spatial evolutions of PSs.
Article
Physics, Multidisciplinary
Dongyang Wang, Biao Yang, Mudi Wang, Ruo-Yang Zhang, Xiao Li, Z. Q. Zhang, Shuang Zhang, C. T. Chan
Summary: This study investigates a photon multiple nodal links system, where nodal lines of nonadjacent bands are examined through symmetry constraints on frame charges, and the existence of nodal lines between higher bands is predicted using an orthogonal nodal chain.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
Biao Yang, Qinghua Guo, Dongyang Wang, Hanyu Wang, Lingbo Xia, Wei Xu, Meng Kang, Ruo-Yang Zhang, Zhao-Qing Zhang, Zhihong Zhu, C. T. Chan
Summary: We propose the concept of scalar topological photonics and experimentally validate it by employing a nested meta-crystal configuration using connected coaxial waveguides. This approach exhibits scalar-wave-like band dispersions, making the search for photonic topological phases easier and the surface states can be exposed to air, making it well-suited for practical applications.
Article
Physics, Multidisciplinary
Jing Hu, Ruo-Yang Zhang, Yixiao Wang, Xiaoping Ouyang, Yifei Zhu, Hongwei Jia, Che Ting Chan
Summary: A characteristic feature of non-Hermitian systems is the presence of exceptional points, where eigenvalues and eigenstates coalesce. Additionally, non-Hermitian systems can exhibit a richer degeneracy morphology known as the swallowtail catastrophe. In this study, the authors demonstrate the existence of the swallowtail catastrophe in non-Hermitian systems with both parity-time and pseudo-Hermitian symmetries, and experimentally observe its degeneracy features.
Article
Optics
Hongwei Jia, Mudi Wang, Shaojie Ma, Ruo-Yang Zhang, Jing Hu, Dongyang Wang, Che Ting Chan
Summary: We propose an experimental scheme for realizing chiral Landau levels in a two-dimensional photonic system by introducing an inhomogeneous effective mass and breaking local parity-inversion symmetries. The synthetic in-plane magnetic field generated couples with the Dirac quasi-particles, inducing the zeroth-order chiral Landau levels and experimentally observing their one-way propagation characteristics. The robust transport of the chiral zeroth mode against defects in the system is also tested.
LIGHT-SCIENCE & APPLICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Tianshu Jiang, Ruo-Yang Zhang, Qinghua Guo, Biao Yang, C. T. Chan
Summary: This paper proposes the concept of two-dimensional (2D) non-Abelian topological insulators, which can explain the energy distributions of the edge states and corner states in systems with parity-time symmetry. The authors establish constraints on the 2D Zak phase and polarization based on non-Abelian band topology. They demonstrate that the corner states in some 2D systems can be explained as the boundary mode of the one-dimensional edge states arising from the multiband non-Abelian topology of the system. In addition, the authors propose the use of off-diagonal Berry phase as complementary information for predicting edge states in non-Abelian topological insulators.
