scholarly journals Accidental degeneracy and berry phase of resonant states

2008 ◽  
pp. 257-281 ◽  
Author(s):  
A. Mondragón ◽  
E. Hernández
Keyword(s):  
Berry Phase ◽  
Resonant States ◽  
Accidental Degeneracy

scholarly journals Pseudospin-1 Physics of Photonic Crystals

Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
A. Fang ◽  
Z. Q. Zhang ◽  
Steven G. Louie ◽  
C. T. Chan
Keyword(s):  
Photonic Crystals ◽  
Recent Progress ◽  
Berry Phase ◽  
Nodal Point ◽  
Band Shift ◽  
Effective Spin ◽  
Klein Tunneling ◽  
Accidental Degeneracy ◽  
Photonic States ◽  
Zero Index

We review some recent progress in the exploration of pseudospin-1 physics using dielectric photonic crystals (PCs). We show some physical implications of the PCs exhibiting an accidental degeneracy induced conical dispersion at the Γ point, such as the realization of zero refractive index medium and the zero Berry phase of a loop around the nodal point. The photonic states of such PCs near the Dirac-like point can be described by an effective spin-orbit Hamiltonian of pseudospin-1. The wave propagation in the positive, negative, and zero index media can be unified within a framework of pseudospin-1 description. A scale change in PCs results in a rigid band shift of the Dirac-like cone, allowing for the manipulation of waves in pseudospin-1 systems in much the same way as applying a gate voltage in pseudospin-1/2 graphene. The transport of waves in pseudospin-1 systems exhibits many interesting phenomena, including super Klein tunneling, robust supercollimation, and unconventional Anderson localization. The transport properties of pseudospin-1 systems are distinct from their counterparts in pseudospin-1/2 systems, which will also be presented for comparison.

scholarly journals Pseudospin-1 Physics of Photonic Crystals

Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
A. Fang ◽  
Z. Q. Zhang ◽  
Steven G. Louie ◽  
C. T. Chan
Keyword(s):  
Photonic Crystals ◽  
Recent Progress ◽  
Berry Phase ◽  
Nodal Point ◽  
Band Shift ◽  
Effective Spin ◽  
Klein Tunneling ◽  
Accidental Degeneracy ◽  
Photonic States ◽  
Zero Index

We review some recent progress in the exploration of pseudospin-1 physics using dielectric photonic crystals (PCs). We show some physical implications of the PCs exhibiting an accidental degeneracy induced conical dispersion at the Γ point, such as the realization of zero refractive index medium and the zero Berry phase of a loop around the nodal point. The photonic states of such PCs near the Dirac-like point can be described by an effective spin-orbit Hamiltonian of pseudospin-1. The wave propagation in the positive, negative, and zero index media can be unified within a framework of pseudospin-1 description. A scale change in PCs results in a rigid band shift of the Dirac-like cone, allowing for the manipulation of waves in pseudospin-1 systems in much the same way as applying a gate voltage in pseudospin-1/2 graphene. The transport of waves in pseudospin-1 systems exhibits many interesting phenomena, including super Klein tunneling, robust supercollimation, and unconventional Anderson localization. The transport properties of pseudospin-1 systems are distinct from their counterparts in pseudospin-1/2 systems, which will also be presented for comparison.

ALPHA-PARTICLE RESONANT STATES IN MEDIUM WEIGHT NUCLEI

1971 ◽  
Vol 32 (C6) ◽  
pp. C6-185-C6-187
Author(s):  
A. DUDEK ◽  
P. E. HODGSON
Keyword(s):  
Alpha Particle ◽  
Resonant States ◽  
Medium Weight

Decay of resonant states and determination of their quantum numbers

1970 ◽  
Vol 101 (8) ◽  
pp. 655-696 ◽  
Author(s):  
M.S. Dubovikov ◽  
Yurii A. Simonov
Keyword(s):  
Quantum Numbers ◽  
Resonant States

The mathematics of harmony and resonant states of consciousness

2017 ◽  
Vol 28 (4) ◽  
pp. 357-363
Author(s):  
Scott A. Olsen
Keyword(s):  
States Of Consciousness ◽  
Resonant States

scholarly journals Interface-induced sign reversal of the anomalous Hall effect in magnetic topological insulator heterostructures

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Fei Wang ◽  
Xuepeng Wang ◽  
Yi-Fan Zhao ◽  
Di Xiao ◽  
Ling-Jie Zhou ◽  
...  
Keyword(s):  
Hall Effect ◽  
Electric Fields ◽  
First Principles ◽  
Berry Phase ◽  
Condensed Matter ◽  
Anomalous Hall Effect ◽  
First Principles Calculations ◽  
Sign Reversal ◽  
Berry Curvature ◽  
Topological Materials

AbstractThe Berry phase picture provides important insights into the electronic properties of condensed matter systems. The intrinsic anomalous Hall (AH) effect can be understood as the consequence of non-zero Berry curvature in momentum space. Here, we fabricate TI/magnetic TI heterostructures and find that the sign of the AH effect in the magnetic TI layer can be changed from being positive to negative with increasing the thickness of the top TI layer. Our first-principles calculations show that the built-in electric fields at the TI/magnetic TI interface influence the band structure of the magnetic TI layer, and thus lead to a reconstruction of the Berry curvature in the heterostructure samples. Based on the interface-induced AH effect with a negative sign in TI/V-doped TI bilayer structures, we create an artificial “topological Hall effect”-like feature in the Hall trace of the V-doped TI/TI/Cr-doped TI sandwich heterostructures. Our study provides a new route to create the Berry curvature change in magnetic topological materials that may lead to potential technological applications.

scholarly journals A hybrid broadband metalens operating at ultraviolet frequencies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Farhan Ali ◽  
Serap Aksu
Keyword(s):  
Dielectric Material ◽  
Berry Phase ◽  
Uv Light ◽  
Fdtd Method ◽  
Numerical Aperture ◽  
Limited Range ◽  
Unit Cell ◽  
Dielectric Constants ◽  
Phase Method ◽  
Frequency Range

AbstractThe investigation on metalenses have been rapidly developing, aiming to bring compact optical devices with superior properties to the market. Realizing miniature optics at the UV frequency range in particular has been challenging as the available transparent materials have limited range of dielectric constants. In this work we introduce a low absorption loss and low refractive index dielectric material magnesium oxide, MgO, as an ideal candidate for metalenses operating at UV frequencies. We theoretically investigate metalens designs capable of efficient focusing over a broad UV frequency range (200–400 nm). The presented metalenses are composed of sub-wavelength MgO nanoblocks, and characterized according to the geometric Pancharatnam–Berry phase method using FDTD method. The presented broadband metalenses can focus the incident UV light on tight focal spots (182 nm) with high numerical aperture ($$\hbox {NA}\approx 0.8$$ NA ≈ 0.8 ). The polarization conversion efficiency of the metalens unit cell and focusing efficiency of the total metalens are calculated to be as high as 94%, the best value reported in UV range so far. In addition, the metalens unit cell can be hybridized to enable lensing at multiple polarization states. The presented highly efficient MgO metalenses can play a vital role in the development of UV nanophotonic systems and could pave the way towards the world of miniaturization.

scholarly journals Properties of the Expansion of the Decaying Wave Solution in Terms of Resonant States

2020 ◽  
Vol 1540 ◽  
pp. 012008
Author(s):  
G García-Calderón
Keyword(s):  
Wave Solution ◽  
Resonant States

scholarly journals Enhancing the Optical Efficiency of Near-Eye Displays with Liquid Crystal Optics

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 107
Author(s):  
Tao Zhan ◽  
En-Lin Hsiang ◽  
Kun Li ◽  
Shin-Tson Wu
Keyword(s):  
Virtual Reality ◽  
Liquid Crystal ◽  
High Efficiency ◽  
Berry Phase ◽  
Optical Element ◽  
Liquid Crystal Polymer ◽  
Proof Of Concept ◽  
Optical Efficiency ◽  
Crystal Polymer ◽  
Light Efficiency

We demonstrate a light efficient virtual reality (VR) near-eye display (NED) design based on a directional display panel and a diffractive deflection film (DDF). The DDF was essentially a high-efficiency Pancharatnam-Berry phase optical element made of liquid crystal polymer. The essence of this design is directing most of the display light into the eyebox. The proposed method is applicable for both catadioptric and dioptric VR lenses. A proof-of-concept experiment was conducted with off-the-shelf optical parts, where the light efficiency was enhanced by more than 2 times.

Rotational Doppler Frequency Shift from Time‐Evolving High‐Order Pancharatnam–Berry Phase: A Metasurface Approach

2021 ◽  
pp. 2000576
Author(s):  
Fuyong Yue ◽  
A. Aadhi ◽  
Riccardo Piccoli ◽  
Vincenzo Aglieri ◽  
Roberto Macaluso ◽  
...  
Keyword(s):  
Frequency Shift ◽  
Berry Phase ◽  
Doppler Frequency ◽  
Doppler Frequency Shift ◽  
High Order
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