Gui-Geng Liu
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View article: Gauge-field-induced duality group in metamaterials
Gauge-field-induced duality group in metamaterials Open
Dualities are mathematical mappings that establish counterintuitive connections between two seemingly unrelated physical systems, enabling the simplification and reinterpretation of complex systems via duality transformations. Recent break…
View article: Chiral Valley Edge States
Chiral Valley Edge States Open
Valleytronics has emerged as a promising paradigm, enabling comprehensive control of the valley degree of freedom (DoF) for energy-efficient and high-speed information processing. However, backscattering-induced valley depolarization remai…
View article: Self-induced topological edge states in a lattice with onsite nonlinearity
Self-induced topological edge states in a lattice with onsite nonlinearity Open
Topological edge states typically arise at the boundaries of topologically nontrivial structures or at interfaces between regions with differing topological invariants. When topological systems are extended into the nonlinear regime, linea…
View article: Realization of a three-dimensional photonic higher-order topological insulator
Realization of a three-dimensional photonic higher-order topological insulator Open
The discovery of photonic higher-order topological insulators (HOTIs) has expanded our understanding of band topology, offering robust lower-dimensional boundary states for photonic devices. However, realizing three-dimensional (3D) photon…
View article: Observation of non-Hermitian topological disclination states and charge fractionalization
Observation of non-Hermitian topological disclination states and charge fractionalization Open
There has been significant interest in exploring topological disclination states, which effectively probe the band topology of the host material beyond the conventional bulk-edge correspondence. While most studies in this area have primari…
View article: Abrupt lateral beam shifts from terahertz quasi-bound states in the continuum
Abrupt lateral beam shifts from terahertz quasi-bound states in the continuum Open
Bound states in the continuum (BICs) are notable in photonics for their infinite Q factors. Perturbed BICs, or quasi-BICs (QBICs), have finite but ultra-high Q factors, enabling external coupling. So far, most studies have focused on the m…
View article: Realization of Topology-controlled Photonic Cavities in a Valley Photonic Crystal
Realization of Topology-controlled Photonic Cavities in a Valley Photonic Crystal Open
We report an experimental realization of a new type of topology-controlled photonic cavities in valley photonic crystals by adopting judiciously oriented mirrors to localize the valley-polarized edge states along their propagation path. By…
View article: Topological disclination states and charge fractionalization in a non-Hermitian lattice
Topological disclination states and charge fractionalization in a non-Hermitian lattice Open
We show that a non-Hermitian lattice with a disclination can host topological disclination states that are induced by on-site gain and loss. The disclination states are inherently non-Hermitian as they do not exist in the limit of zero gai…
View article: Photonic bilayer Chern insulator with corner states
Photonic bilayer Chern insulator with corner states Open
Photonic Chern insulators can be implemented in gyromagnetic photonic crystals with broken time-reversal (TR) symmetry. They exhibit gapless chiral edge states (CESs), enabling unidirectional propagation and demonstrating exceptional resil…
View article: Realization of a three-dimensional photonic higher-order topological insulator
Realization of a three-dimensional photonic higher-order topological insulator Open
The discovery of photonic higher-order topological insulators (HOTIs) has significantly expanded our understanding of band topology and provided unprecedented lower-dimensional topological boundary states for robust photonic devices. Howev…
View article: Realization of a three-dimensional photonic higher-order topological insulator
Realization of a three-dimensional photonic higher-order topological insulator Open
The discovery of photonic higher-order topological insulators (HOTIs) has significantly expanded our understanding of band topology and provided unprecedented lower-dimensional topological boundary states for robust photonic devices. Howev…
View article: Realization of a quadrupole topological insulator phase in a gyromagnetic photonic crystal
Realization of a quadrupole topological insulator phase in a gyromagnetic photonic crystal Open
The field of topological photonics was initiated with the realization of a Chern insulator phase in a gyromagnetic photonic crystal (PhC) with broken time-reversal symmetry (T), hosting chiral edge states that are topologically protected p…
View article: Three-dimensional Topological Photonic Crystals (Invited Review)
Three-dimensional Topological Photonic Crystals (Invited Review) Open
View article: Localization of chiral edge states by the non-Hermitian skin effect
Localization of chiral edge states by the non-Hermitian skin effect Open
Quantum Hall systems host chiral edge states extending along the one-dimensional boundary of any two-dimensional sample. In solid state materials, the edge states serve as perfectly robust transport channels that produce a quantised Hall c…
View article: Brillouin Klein space and half-turn space in three-dimensional acoustic crystals
Brillouin Klein space and half-turn space in three-dimensional acoustic crystals Open
The Bloch band theory and Brillouin zone (BZ) that characterize wave behaviors in periodic mediums are two cornerstones of contemporary physics ranging from condensed matter to topological physics. Recent theoretical breakthrough revealed …
View article: AdS/CFT Correspondence in Hyperbolic Lattices
AdS/CFT Correspondence in Hyperbolic Lattices Open
The celebrated anti-de Sitter/conformal field theory (AdS/CFT) correspondence1-3, also known as the gravity/gauge duality, posits a dual relationship between the quantum gravity in an AdS spacetime and the CFT defined on its lower-dimensio…
View article: Topological antichiral surface states in a magnetic Weyl photonic crystal
Topological antichiral surface states in a magnetic Weyl photonic crystal Open
View article: Realization of a quadrupole topological insulator phase in a gyromagnetic photonic crystal
Realization of a quadrupole topological insulator phase in a gyromagnetic photonic crystal Open
The field of topological photonics was initiated with the realization of a Chern insulator phase in a gyromagnetic photonic crystal (PhC) with broken time-reversal symmetry (T), hosting chiral edge states that are topologically protected p…
View article: Spinful Topological Phases in Acoustic Crystals with Projective <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>P</mml:mi><mml:mi>T</mml:mi></mml:math> Symmetry
Spinful Topological Phases in Acoustic Crystals with Projective Symmetry Open
For the classification of topological phases of matter, an important consideration is whether a system is spinless or spinful, as these two classes have distinct symmetry algebra that gives rise to fundamentally different topological phase…
View article: Novel topological phases in gyromagnetic photonic crystals
Novel topological phases in gyromagnetic photonic crystals Open
Topological phases have revolutionized both condensed matter and classical wave physics, and photonic systems have proven to be versatile platforms for exploring exotic topological phenomena. This thesis investigates novel topological phas…
View article: Beam splitter benefits from topological antichiral edge states
Beam splitter benefits from topological antichiral edge states Open
A functional beam splitter is proposed with recently realized topological antichiral edge states, which offer multi-channel utilization, crosstalk-proof performance, and robustness against defects and obstacles.
View article: Observation of multiple rotons and multidirectional roton-like dispersion relations in acoustic metamaterials
Observation of multiple rotons and multidirectional roton-like dispersion relations in acoustic metamaterials Open
Roton dispersion relations were firstly predicted by Landau and have been extensively explored in correlated quantum systems at low temperatures. Recently, the roton-like dispersion relations were theoretically extended to classical acoust…
View article: Extended Metasurface Spin Functionalities from Rotation of Elements
Extended Metasurface Spin Functionalities from Rotation of Elements Open
Metasurfaces are a class of planar optical components that are engineered to manipulate electromagnetic waves, including their spin states in terms of circular polarizations. For example, the Pancharatnam–Berry (PB) phase has been exploite…
View article: Topological Chern vectors in three-dimensional photonic crystals
Topological Chern vectors in three-dimensional photonic crystals Open
View article: Observation of Dirac Hierarchy in Three-Dimensional Acoustic Topological Insulators
Observation of Dirac Hierarchy in Three-Dimensional Acoustic Topological Insulators Open
Dirac cones (DCs) play a pivotal role in various unique phenomena ranging from massless electrons in graphene to robust surface states in topological insulators (TIs). Recent studies have theoretically revealed a full Dirac hierarchy compr…
View article: Spinful topological phases in acoustic crystals with projective PT symmetry
Spinful topological phases in acoustic crystals with projective PT symmetry Open
For the classification of topological phases of matter, an important consideration is whether a system is spinless or spinful, as these two classes have distinct symmetry algebra that gives rise to fundamentally different topological phase…
View article: Topology with memory in nonlinear driven-dissipative photonic lattices
Topology with memory in nonlinear driven-dissipative photonic lattices Open
We consider a photonic lattice of nonlinear lossy resonators subjected to a coherent drive, where the system remembers its topological phase. Initially, the system is topologically trivial. After the application of an additional coherent p…
View article: Observation of roton-like dispersion relations in acoustic metamaterials
Observation of roton-like dispersion relations in acoustic metamaterials Open
Roton dispersion relations, displaying a pronounced "roton" minimum at finite momentum, were firstly predicted by Landau and have been extensively explored in correlated quantum systems at low temperatures. Recently, the roton-like dispers…
View article: Observation of roton-like dispersion relations in acoustic metamaterials
Observation of roton-like dispersion relations in acoustic metamaterials Open
Roton dispersion relations, displaying a pronounced “roton” minimum at finite momentum, were firstly predicted by Landau and have been extensively explored in correlated quantum systems at low temperatures. Recently, the roton-like dispers…
View article: Observation of topological edge states in thermal diffusion
Observation of topological edge states in thermal diffusion Open
The topological band theory predicts that bulk materials with nontrivial topological phases support topological edge states. This phenomenon is universal for various wave systems and has been widely observed for electromagnetic and acousti…