scholarly journals Dynamically characterizing topological phases by high-order topological charges

2021 ◽  
Vol 103 (5) ◽  
Author(s):  
Wei Jia ◽  
Lin Zhang ◽  
Long Zhang ◽  
Xiong-Jun Liu
Keyword(s):  
High Order ◽  
Topological Phases ◽  
Topological Charges

scholarly journals Quantum Dynamical Characterization and Simulation of Topological Phases With High-Order Band Inversion Surfaces

PRX Quantum ◽  
2021 ◽  
Vol 2 (2) ◽  
Author(s):  
Xiang-Long Yu ◽  
Wentao Ji ◽  
Lin Zhang ◽  
Ya Wang ◽  
Jiansheng Wu ◽  
...  
Keyword(s):  
High Order ◽  
Topological Phases ◽  
Quantum Dynamical ◽  
Band Inversion

scholarly journals Tunable Beam Steering, Focusing and Generating of Orbital Angular Momentum Vortex Beams Using High-Order Patch Array

2019 ◽  
Vol 9 (15) ◽  
pp. 2949 ◽  
Author(s):  
Zhiping Yin ◽  
Qun Zheng ◽  
Kai Guo ◽  
Zhongyi Guo
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Phase Modulation ◽  
Beam Steering ◽  
Phase Shifters ◽  
High Order ◽  
Scanning Angle ◽  
Beam Focusing ◽  
Vortex Beams ◽  
Topological Charges

In this paper, a tunable patch array based on high-order is proposed at the frequency of 300 GHz, achieving active controllable beam steering, focusing and generation of orbital angular momentum vortex beams. It has been demonstrated that the patch array can achieve wide beam scanning angle by controlling the phase of array elements with tunable phase shifters. Meanwhile, beam focusing on the specified position can also be realized by phase modulation of array elements based on the focusing theory. In addition, we also designed a patch array to generate vortex beams with multiple topological charges by high-order modes. The performances show that the patch antenna array we designed has a good application prospect.

High-order topological charges measurement of LG vortex beams with a modified Mach–Zehnder interferometer

Optik ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 4378-4381 ◽  
Author(s):  
Fangjie Lv ◽  
Xinzhong Li ◽  
Yuping Tai ◽  
Liping Zhang ◽  
Zhaogang Nie ◽  
...  
Keyword(s):  
High Order ◽  
Zehnder Interferometer ◽  
Vortex Beams ◽  
Topological Charges ◽  
Mach Zehnder Interferometer

scholarly journals Non-Abelian band topology in noninteracting metals

Science ◽  
2019 ◽  
Vol 365 (6459) ◽  
pp. 1273-1277 ◽  
Author(s):  
QuanSheng Wu ◽  
Alexey A. Soluyanov ◽  
Tomáš Bzdušek
Keyword(s):  
Nodal Line ◽  
Time Inversion ◽  
Topological Phases ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Energy Bands ◽  
Topological Stability ◽  
One Dimensional ◽  
Biaxial Nematics ◽  
Topological Charges

Electron energy bands of crystalline solids generically exhibit degeneracies called band-structure nodes. Here, we introduce non-Abelian topological charges that characterize line nodes inside the momentum space of crystalline metals with space-time inversion (𝒫𝒯) symmetry and with weak spin-orbit coupling. We show that these are quaternion charges, similar to those describing disclinations in biaxial nematics. Starting from two-band considerations, we develop the complete many-band description of nodes in the presence of 𝒫𝒯 and mirror symmetries, which allows us to investigate the topological stability of nodal chains in metals. The non-Abelian charges put strict constraints on the possible nodal-line configurations. Our analysis goes beyond the standard approach to band topology and implies the existence of one-dimensional topological phases not present in existing classifications.

Determination of the Burgers vector of a dislocation in a Fe-Mn alloy by weak-beam image in HVEM

1978 ◽  
Vol 36 (1) ◽  
pp. 330-331
Author(s):  
Y. Ishida ◽  
H. Ishida ◽  
K. Kohra ◽  
H. Ichinose
Keyword(s):  
High Order ◽  
Simulation Technique ◽  
The Other ◽  
Image Simulation ◽  
Diffraction Vector ◽  
Burgers Vector ◽  
Weak Beam ◽  
Beam Image ◽  
Edge Component

IntroductionA simple and accurate technique to determine the Burgers vector of a dislocation has become feasible with the advent of HVEM. The conventional image vanishing technique(1) using Bragg conditions with the diffraction vector perpendicular to the Burgers vector suffers from various drawbacks; The dislocation image appears even when the g.b = 0 criterion is satisfied, if the edge component of the dislocation is large. On the other hand, the image disappears for certain high order diffractions even when g.b ≠ 0. Furthermore, the determination of the magnitude of the Burgers vector is not easy with the criterion. Recent image simulation technique is free from the ambiguities but require too many parameters for the computation. The weak-beam “fringe counting” technique investigated in the present study is immune from the problems. Even the magnitude of the Burgers vector is determined from the number of the terminating thickness fringes at the exit of the dislocation in wedge shaped foil surfaces.

The usefulness of high index low symmetry zone axes for holz line analysis

1987 ◽  
Vol 45 ◽  
pp. 384-385
Author(s):  
C. M. Sung ◽  
D. B. Williams
Keyword(s):  
Lattice Parameter ◽  
High Order ◽  
Zone Axis ◽  
High Index ◽  
High Symmetry ◽  
Second Phases ◽  
Line Patterns ◽  
Low Symmetry ◽  
Line Analysis

Researchers have tended to use high symmetry zone axes (e.g. <111> <114>) for High Order Laue Zone (HOLZ) line analysis since Jones et al reported the origin of HOLZ lines and described some of their applications. But it is not always easy to find HOLZ lines from a specific high symmetry zone axis during microscope operation, especially from second phases on a scale of tens of nanometers. Therefore it would be very convenient if we can use HOLZ lines from low symmetry zone axes and simulate these patterns in order to measure lattice parameter changes through HOLZ line shifts. HOLZ patterns of high index low symmetry zone axes are shown in Fig. 1, which were obtained from pure Al at -186°C using a double tilt cooling holder. Their corresponding simulated HOLZ line patterns are shown along with ten other low symmetry orientations in Fig. 2. The simulations were based upon kinematical diffraction conditions.

Are HOLZ lines kinematic in off-zone-axis orientation?

1993 ◽  
Vol 51 ◽  
pp. 692-693
Author(s):  
J. M. Zuo ◽  
A. L. Weickenmeier ◽  
R. Holmestad ◽  
J. C. H. Spence
Keyword(s):  
Structure Determination ◽  
Standard Procedure ◽  
High Order ◽  
Zone Axis ◽  
Great Promise ◽  
Line Position ◽  
Measured Intensity ◽  
Constant Intensity ◽  
Axis Orientation ◽  
Diffraction Condition

The application of high order reflections in a weak diffraction condition off the zone axis center, including those in high order laue zones (HOLZ), holds great promise for structure determination using convergent beam electron diffraction (CBED). It is believed that in this case the intensities of high order reflections are kinematic or two-beam like. Hence, the measured intensity can be related to the structure factor amplitude. Then the standard procedure of structure determination in crystallography may be used for solving unknown structures. The dynamic effect on HOLZ line position and intensity in a strongly diffracting zone axis is well known. In a weak diffraction condition, the HOLZ line position may be approximated by the kinematic position, however, it is not clear whether this is also true for HOLZ intensities. The HOLZ lines, as they appear in CBED patterns, do show strong intensity variations along the line especially near the crossing of two lines, rather than constant intensity along the Bragg condition as predicted by kinematic or two beam theory.

Relativistic high-order harmonic generation

2003 ◽  
Vol 50 (3-4) ◽  
pp. 375-386
Author(s):  
D. B. MilosÕeviĆ ◽  
W. Becker
Keyword(s):  
Harmonic Generation ◽  
High Order ◽  
High Order Harmonic Generation ◽  
High Order Harmonic
Sign in / Sign up

Export Citation Format

Share Document