scholarly journals Near- and Far-Field Excitation of Topological Plasmonic Metasurfaces

Photonics ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 81
Author(s):  
Matthew Proctor ◽  
Xiaofei Xiao ◽  
Richard V. Craster ◽  
Stefan A. Maier ◽  
Vincenzo Giannini ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Honeycomb Lattice ◽  
Far Field ◽  
Two Dimensional ◽  
Edge States ◽  
Source Position ◽  
Magnetic Dipoles ◽  
Classical Wave ◽  
Field Excitation ◽  
Crystalline Symmetry

The breathing honeycomb lattice hosts a topologically non-trivial bulk phase due to the crystalline-symmetry of the system. Pseudospin-dependent edge states, which emerge at the interface between trivial and non-trivial regions, can be used for the directional propagation of energy. Using the plasmonic metasurface as an example system, we probe these states in the near- and far-field using a semi-analytical model. We provide the conditions under which directionality was observed and show that it is source position dependent. By probing with circularly-polarised magnetic dipoles out of the plane, we first characterise modes along the interface in terms of the enhancement of source emissions due to the metasurface. We then excite from the far-field with non-zero orbital angular momentum beams. The position-dependent directionality holds true for all classical wave systems with a breathing honeycomb lattice. Our results show that a metasurface in combination with a chiral two-dimensional material, could be used to guide light effectively on the nanoscale.

scholarly journals Lasing in optically induced gap states in photonic graphene

2018 ◽  
Vol 5 (6) ◽  
Author(s):  
Marijana Milićević ◽  
Olivier Bleu ◽  
Dmitry Solnyshkov ◽  
Isabelle Sagnes ◽  
Aristide Lemaître ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Optical Potential ◽  
Honeycomb Lattice ◽  
Two Dimensional ◽  
Hexagonal Symmetry ◽  
Defect States ◽  
Excitation Beam ◽  
Spatial Shape ◽  
Gap States

We report polariton lasing in localised gap states in a honeycomb lattice of coupled micropillars. Localisation of the modes is induced by the optical potential created by the excitation beam, requiring no additional engineering of the otherwise homogeneous polariton lattice. The spatial shape of the gap states arises from the interplay of the orbital angular momentum eigenmodes of the cylindrical potential created by the excitation beam and the hexagonal symmetry of the underlying lattice. Our results provide insights into the engineering of defect states in two-dimensional lattices.

Dual modulation of topological edge states from two-dimensional photonic crystals with lattice shrink

2021 ◽  
pp. 2150236
Author(s):  
Xiao-Xue Li ◽  
Yun-Tuan Fang ◽  
Li-Xia Yang
Keyword(s):  
Photonic Crystals ◽  
Edge State ◽  
Wide Bandgap ◽  
Two Dimensional ◽  
Edge States ◽  
Source Position ◽  
State Structure ◽  
Intense Field ◽  
Flat Edge ◽  
Field Localization

The current topological edge states lack dynamical modulation and the intense field localization effect. To solve these problems, we construct a topological edge state structure based on two-dimensional photonic crystals with lattice shrink. Through the optimization of structure parameters, a nearly flat edge state dispersion curve occurs in a wide bandgap. The topological edge states with intense field localization take on some unique properties such that the transport directions can be controlled by both the source spin and the source position. The transport modes can be dynamically switched between the two opposite unidirectional channels just through moving the source position.

Ferromagnetic dual topological insulator in a two-dimensional honeycomb lattice

2020 ◽  
Vol 7 (9) ◽  
pp. 2431-2438
Author(s):  
Hao Wang ◽  
Ning Mao ◽  
Chengwang Niu ◽  
Shiying Shen ◽  
Myung-Hwan Whangbo ◽  
...  
Keyword(s):  
Hall Effect ◽  
Topological Insulator ◽  
Topological Insulators ◽  
Anomalous Hall Effect ◽  
Topological Invariant ◽  
Honeycomb Lattice ◽  
Two Dimensional ◽  
Edge States ◽  
Quantum Anomalous Hall Effect ◽  
Significant Attention

Magnetic topological insulators (TIs), including the quantum anomalous Hall effect and antiferromagnetic TIs, have attracted significant attention owing to the exotic properties they give rise to, however, ferromagnetic TIs with gapless surface/edge states and a nonzero topological invariant have not been reported so far.

scholarly journals Bulk-edge correspondence of classical diffusion phenomena

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tsuneya Yoshida ◽  
Yasuhiro Hatsugai
Keyword(s):  
Temperature Field ◽  
Diffusion Equation ◽  
Edge State ◽  
Lattice System ◽  
Honeycomb Lattice ◽  
Two Dimensional ◽  
Winding Number ◽  
Edge States ◽  
Diffusive Dynamics ◽  
Diffusion Phenomena

AbstractWe elucidate that diffusive systems, which are widely found in nature, can be a new platform of the bulk-edge correspondence, a representative topological phenomenon. Using a discretized diffusion equation, we demonstrate the emergence of robust edge states protected by the winding number for one- and two-dimensional systems. These topological edge states can be experimentally accessible by measuring diffusive dynamics at edges. Furthermore, we discover a novel diffusion phenomenon by numerically simulating the distribution of temperatures for a honeycomb lattice system; the temperature field with wavenumber $$\pi $$ π cannot diffuse to the bulk, which is attributed to the complete localization of the edge state.

scholarly journals Strain-Induced Quantum Spin Hall Effect in Two-Dimensional Methyl-Functionalized Silicene SiCH3

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 698 ◽  
Author(s):  
Ceng-Ceng Ren ◽  
Wei-Xiao Ji ◽  
Shu-Feng Zhang ◽  
Chang-Wen Zhang ◽  
Ping Li ◽  
...  
Keyword(s):  
Hexagonal Boron Nitride ◽  
Quantum Spin ◽  
Honeycomb Lattice ◽  
Potential Candidate ◽  
Two Dimensional ◽  
Edge States ◽  
Spin Orbital ◽  
Spintronic Devices ◽  
Potential Applications ◽  
Quantum Spin Hall

Quantum Spin Hall (QSH) has potential applications in low energy consuming spintronic devices and has become a researching hotspot recently. It benefits from insulators feature edge states, topologically protected from backscattering by time-reversal symmetry. The properties of methyl functionalized silicene (SiCH3) have been investigated using first-principles calculations, which show QSH effect under reasonable strain. The origin of the topological characteristic of SiCH3, is mainly associated with the s-pxy orbitals band inversion at Γ point, whilst the band gap appears under the effect of spin-orbital coupling (SOC). The QSH phase of SiCH3 is confirmed by the topological invariant Z2 = 1, as well as helical edge states. The SiCH3 supported by hexagonal boron nitride (BN) film makes it possible to observe its non-trivial topological phase experimentally, due to the weak interlayer interaction. The results of this work provide a new potential candidate for two-dimensional honeycomb lattice spintronic devices in spintronics.

Theoretical realization of two-dimensional Dirac/Weyl line-node and traversing edge states in penta-X2Y monolayers

2021 ◽  
Vol 23 ◽  
pp. 101057
Author(s):  
Lirong Wang ◽  
Lei Jin ◽  
Guodong Liu ◽  
Ying Liu ◽  
Xuefang Dai ◽  
...  
Keyword(s):  
Two Dimensional ◽  
Edge States ◽  
Line Node

scholarly journals Robust zero modes in disordered two-dimensional honeycomb lattice with Kekulé bond ordering

2021 ◽  
pp. 168440
Author(s):  
Tohru Kawarabayashi ◽  
Yuya Inoue ◽  
Ryo Itagaki ◽  
Yasuhiro Hatsugai ◽  
Hideo Aoki
Keyword(s):  
Honeycomb Lattice ◽  
Two Dimensional ◽  
Zero Modes

scholarly journals Schwarzian quantum mechanics as a Drinfeld-Sokolov reduction of BF theory

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Fridrich Valach ◽  
Donald R. Youmans
Keyword(s):  
Quantum Mechanics ◽  
Partition Function ◽  
Gauge Group ◽  
Path Integral ◽  
Coadjoint Orbits ◽  
Two Dimensional ◽  
Edge States ◽  
Class Constraint ◽  
Action Functional ◽  
Bf Theory

Abstract We give an interpretation of the holographic correspondence between two-dimensional BF theory on the punctured disk with gauge group PSL(2, ℝ) and Schwarzian quantum mechanics in terms of a Drinfeld-Sokolov reduction. The latter, in turn, is equivalent to the presence of certain edge states imposing a first class constraint on the model. The constrained path integral localizes over exceptional Virasoro coadjoint orbits. The reduced theory is governed by the Schwarzian action functional generating a Hamiltonian S1-action on the orbits. The partition function is given by a sum over topological sectors (corresponding to the exceptional orbits), each of which is computed by a formal Duistermaat-Heckman integral.

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