Mapping plasmonic topological states at the nanoscale

Nanoscale ◽  
2015 ◽  
Vol 7 (28) ◽  
pp. 11904-11908 ◽  
Author(s):  
Ivan S. Sinev ◽  
Ivan S. Mukhin ◽  
Alexey P. Slobozhanyuk ◽  
Alexander N. Poddubny ◽  
Andrey E. Miroshnichenko ◽  
...  
Keyword(s):  
Experimental Observation ◽  
Edge States ◽  
Topological States

We report on the first experimental observation of topological edge states in zigzag chains of plasmonic nanodisks.

scholarly journals Topological Atomic Chains on 2D Hybrid Structure

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3289
Author(s):  
Tomasz Kwapiński ◽  
Marcin Kurzyna
Keyword(s):  
Tight Binding ◽  
Wide Band ◽  
Hybrid Structure ◽  
Spectral Density Function ◽  
Hybrid Structures ◽  
Function Technique ◽  
Edge States ◽  
Surface Singularities ◽  
Atomic Chains ◽  
Topological States

Mid-gap 1D topological states and their electronic properties on different 2D hybrid structures are investigated using the tight binding Hamiltonian and the Green’s function technique. There are considered straight armchair-edge and zig-zag Su–Schrieffer–Heeger (SSH) chains coupled with real 2D electrodes which density of states (DOS) are characterized by the van Hove singularities. In this work, it is shown that such 2D substrates substantially influence topological states end evoke strong asymmetry in their on-site energetic structures, as well as essential modifications of the spectral density function (local DOS) along the chain. In the presence of the surface singularities the SSH topological state is split, or it is strongly localized and becomes dispersionless (tends to the atomic limit). Additionally, in the vicinity of the surface DOS edges this state is asymmetrical and consists of a wide bulk part together with a sharp localized peak in its local DOS structure. Different zig-zag and armachair-edge configurations of the chain show the spatial asymmetry in the chain local DOS; thus, topological edge states at both chain ends can appear for different energies. These new effects cannot be observed for ideal wide band limit electrodes but they concern 1D topological states coupled with real 2D hybrid structures.

scholarly journals Photonic Topological States in a Two-Dimensional Gyrotropic Photonic Crystal

Crystals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 137 ◽  
Author(s):  
Xiao-Chen Sun ◽  
Cheng He ◽  
Xiao-Ping Liu ◽  
Yi Zou ◽  
Ming-Hui Lu ◽  
...  
Keyword(s):  
Transverse Magnetic ◽  
Quantum Spin ◽  
Necessary Condition ◽  
Complex Conjugate ◽  
Optical Parameters ◽  
Edge States ◽  
Quantum Spin Hall Effect ◽  
Pauli Matrices ◽  
Topological States ◽  
Complete Set

Time-reversal symmetry (TRS) of electrons is associated with an anti-unitary operator with T 2 = − 1 , which induces Kramers degeneracy and plays an important role in realizing the quantum spin Hall effect (QSHE). By contrast, TRS of photons is described by T b 2 = 1 . We point out that due to this difference, TRS is not the necessary condition for the construction of the photonic analogue of the QSHE. Instead, by constructing an artificial pseudo TRS T p with T p 2 = − 1 in a photonic system, one can realize the photonic Kramers degeneracy and a pair of topological protected edge states, a photonic analogue of the QSHE. Specifically, by retrieving the optical parameters of materials with the pseudo TRS, we propose a photonic topological insulator (PTI) utilizing a pair of double-degenerate transverse electric (TE) and transverse magnetic (TM) polarizations to mimic the spin up and down states of the electron. We demonstrate that the unidirectional polarization-dependent transportation of TE and TM edge states can be realized in this system based on computer simulations. For all possible symmetry types, we check the robustness of these topological states by using a complete set of impurities, including three Pauli matrices and one complex conjugate operator. The results show that the PTI is protected by the pseudo TRS T p . In general, an arbitrary pair of optical polarizations on the Bloch sphere can be utilized to construct photonic pseudospin states and the PTI. Our findings confirm the physical meaning of the pseudo TRS and may provide guidance for future PTI designs.

scholarly journals The effect of moiré superstructures on topological edge states in twisted bismuthene homojunctions

2020 ◽  
Vol 6 (23) ◽  
pp. eaba2773 ◽  
Author(s):  
Jian Gou ◽  
Longjuan Kong ◽  
Xiaoyue He ◽  
Yu Li Huang ◽  
Jiatao Sun ◽  
...  
Keyword(s):  
Single Layer ◽  
Scanning Tunneling ◽  
Edge States ◽  
First Principles Calculations ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Spatially Distributed ◽  
Topological States ◽  
Device Applications

Creating and controlling the topological properties of two-dimensional topological insulators is essential for spintronic device applications. Here, we report the successful growth of bismuth homostructure consisting of monolayer bismuthene and single-layer black phosphorus–like Bi (BP-Bi) on the HOPG surface. Combining scanning tunneling microscopy/spectroscopy with noncontact atomic force microscopy, moiré superstructures with twist angles in the bismuth homostructure and the modulation of topological edge states of bismuthene were observed and studied. First-principles calculations reproduced the moiré superlattice and indicated that the structure fluctuation is ascribed to the stacking modes between bismuthene and BP-Bi, which induce spatially distributed interface interactions in the bismuth homostructure. The modulation of topological edge states is directly related to the variation of interlayer interactions. Our results suggest a promising pathway to tailor the topological states through interfacial interactions.

scholarly journals Dark topological valley Hall edge solitons

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Boquan Ren ◽  
Hongguang Wang ◽  
Victor O. Kompanets ◽  
Yaroslav V. Kartashov ◽  
Yongdong Li ◽  
...  
Keyword(s):  
Domain Walls ◽  
Edge State ◽  
Underlying Structure ◽  
Edge States ◽  
Atomic Vapors ◽  
Triangular Domain ◽  
Topological States ◽  
Sharp Corners ◽  
Nontrivial Topology ◽  
Group Velocities

Abstract Topological edge solitons propagating along the edge of a photonic topological insulator are localized self-sustained hybrid states that are immune to defects/disorders due to the protection of the edge states stemming from the nontrivial topology of the system. Here, we predict that exceptionally robust dark valley Hall edge solitons may form at the domain walls between two honeycomb lattices with broken inversion symmetry. The underlying structure can be created with femtosecond laser inscription, it possesses a large bandgap where well-localized dark edge solitons form, and in contrast to systems with broken time-reversal symmetry, it does not require external magnetic fields or complex longitudinal waveguide modulations for the realization of the topological phase. We present the envelope equation allowing constructing dark valley Hall edge solitons analytically. Such solitons propagate without radiation into the bulk of the lattice and can circumvent sharp corners, which allows observing their persistent circulation along the closed triangular domain wall boundary. They survive over huge distances even in the presence of disorder in the underlying lattice. We also investigate interactions of closely located dark topological valley Hall edge solitons and show that they are repulsive and lead to the formation of two gray edge solitons, moving with different group velocities departing from group velocity of the linear edge state on which initial dark solitons were constructed. Our results illustrate that nonlinear valley Hall systems can support a rich variety of new self-sustained topological states and may inspire their investigation in other nonlinear systems, such as atomic vapors and polariton condensates.

scholarly journals Topological edge states of anyon pairs emulated in electric circuits

2021 ◽  
Vol 2015 (1) ◽  
pp. 012127
Author(s):  
A D Rozenblit ◽  
N A Olekhno ◽  
A A Dmitriev ◽  
P S Seregin ◽  
M A Gorlach
Keyword(s):  
Electric Circuit ◽  
Quantum Statistics ◽  
Edge States ◽  
Fractional Quantum ◽  
Electric Circuits ◽  
Numerical Studies ◽  
Topological Quantum ◽  
Theoretical Predictions ◽  
Topological States ◽  
Geometrical Imperfections

Abstract Recent advances in two-particle topological quantum states demonstrate resilience to geometrical imperfections and hold perspectives for robust quantum computations. In this context, particles with fractional quantum statistics, the so-called anyons, attract especial attention. In particular, topological edge states of anyon pairs in one-dimensional chains of coupled cavities were recently predicted to demonstrate localization at one or another edge of the array depending on details of the quantum statistics. In this paper, propose an equivalent electric circuit serving as a classical emulator of such topological states. Detailed numerical studies of resonances in the circuit fully support theoretical predictions, pointing towards future experimental realizations of anyonic states analogs in electrical circuits.

scholarly journals Twisted bulk-boundary correspondence of fragile topology

Science ◽  
2020 ◽  
Vol 367 (6479) ◽  
pp. 794-797 ◽  
Author(s):  
Zhi-Da Song ◽  
Luis Elcoro ◽  
B. Andrei Bernevig
Keyword(s):  
Boundary Conditions ◽  
Topological Insulator ◽  
Experimental Verification ◽  
Real Space ◽  
Two Dimensional ◽  
Edge States ◽  
Quantum Numbers ◽  
Boundary Correspondence ◽  
Topological States ◽  
Twisted Boundary Conditions

A topological insulator reveals its nontrivial bulk through the presence of gapless edge states: This is called the bulk-boundary correspondence. However, the recent discovery of “fragile” topological states with no gapless edges casts doubt on this concept. We propose a generalization of the bulk-boundary correspondence: a transformation under which the gap between the fragile phase and other bands must close. We derive specific twisted boundary conditions (TBCs) that can detect all the two-dimensional eigenvalue fragile phases. We develop the concept of real-space invariants, local good quantum numbers in real space, which fully characterize these phases and determine the number of gap closings under the TBCs. Realizations of the TBCs in metamaterials are proposed, thereby providing a route to their experimental verification.

Replication Data for: Experimental observation of non-Abelian topological charges and edge states

2021 ◽  
Author(s):  
Qinghua Guo ◽  
Tianshu Jiang ◽  
Ruo-Yang Zhang ◽  
Lei Zhang ◽  
Zhao-Qing Zhang ◽  
...  
Keyword(s):  
Experimental Observation ◽  
Edge States ◽  
Topological Charges

scholarly journals Coexisting Edge States and Gapless Bulk in Topological States of Matter

2015 ◽  
Vol 114 (13) ◽  
Author(s):  
Yuval Baum ◽  
Thore Posske ◽  
Ion Cosma Fulga ◽  
Björn Trauzettel ◽  
Ady Stern
Keyword(s):  
Topological States Of Matter ◽  
Edge States ◽  
Topological States

scholarly journals Erratum: “Experimental observation of conductive edge states in weak topological insulator candidate Hf Te5” [APL Mater. 6, 121111 (2018)]

APL Materials ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 109901
Author(s):  
S. Liu ◽  
M. X. Wang ◽  
C. Chen ◽  
X. Xu ◽  
J. Jiang ◽  
...  
Keyword(s):  
Experimental Observation ◽  
Topological Insulator ◽  
Edge States
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