scholarly journals Angular momenta in fields from a rotational mechanical antenna

2021 ◽  
Author(s):  
Yu Mao ◽  
Y. Liu ◽  
Hai Lin
Keyword(s):  
Fourier Transform ◽  
Angular Momentum ◽  
Electric Dipole ◽  
Energy Flow ◽  
Flow Density ◽  
Spin Angular Momentum ◽  
Transform Method ◽  
Rotation Direction ◽  
Binding Force ◽  
Angular Momenta

Abstract Mechanic antennas provide opportunities for human portable, VLF communications, where a rotational dipole emits EM signals with angular momenta. In this paper we analytically derive the electromagnetic fields from a rotational electric dipole using Fourier transform method, and find that the radiated fields from the rotational electric dipole carries nonzero energy flow density in both orbital and spin angular momentum (AM) parts by AM flux tensors. Intuitively, a rotation of a dipole induces a longitudinal orbital angular momentum and a longitudinal spin angular momentum both circulating in the rotation direction. And the binding force for the rotational electric dipole is then shown to result mainly from the Coulomb fields. We believe that our work can provide novel communication designs for portable mechanic antennas.

scholarly journals Inversion of the longitudinal component of spin angular momentum in the focus of a left-handed circularly polarized beam

2020 ◽  
Vol 44 (5) ◽  
pp. 699-706
Author(s):  
A.G. Nalimov ◽  
E.S. Kozlova
Keyword(s):  
Angular Momentum ◽  
Energy Flow ◽  
Longitudinal Component ◽  
Angular Momentum Vector ◽  
Spin Angular Momentum ◽  
Momentum Vector ◽  
Circularly Polarized ◽  
Left Hand ◽  
Left Handed ◽  
Polarized Beam

It has been shown theoretically and numerically that in the sharp focus of a circularly polarized optical vortex, the longitudinal component of the spin angular momentum vector is inverted. Moreover, if the input light to the optical system is left-hand circularly polarized, it has been shown to be right-hand polarized in the focus near the optical axis. Since this effect occurs near the focus where a backward energy flow takes place, such an inversion of the spin angular momentum can be used to detect the backward energy flow.

scholarly journals Force-Mediating Particle of Coupling of Spin Angular Momenta

2021 ◽  
pp. 49-65
Author(s):  
ShaoXu Ren
Keyword(s):  
Angular Momentum ◽  
Topological Space ◽  
Spin Coupling ◽  
Spin Angular Momentum ◽  
Spin Particle ◽  
Angular Momenta

In this paper, a hypothesis is proposed, that something similar to what happen to the puzzle of the energy losing in decay of neutron may also occur to the puzzle of the sum losing of the z-components of spin angular momenta in the synthetic course of spin coupling in Spin Topological Space. The former puzzle is related to hidden neutrial antineutrino that carries a small amount of energy away, the latter puzzle is related to hidden "constructive" zero-spin particle playing the role of a force-mediator that carries some amount of spin angular momentum, which just offsets the same amount of angular momentum losing in the formation of spin coupling.

scholarly journals Spin angular momentum density and transverse energy flow of tightly focused kaleidoscope-structured vector optical fields

APL Photonics ◽  
2019 ◽  
Vol 4 (9) ◽  
pp. 096102 ◽  
Author(s):  
Yue Pan ◽  
Xu-Zhen Gao ◽  
Guan-Lin Zhang ◽  
Yongnan Li ◽  
Chenghou Tu ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Energy Flow ◽  
Transverse Energy ◽  
Momentum Density ◽  
Spin Angular Momentum ◽  
Optical Fields ◽  
Transverse Energy Flow

scholarly journals A transverse energy flow at the tight focus of light with higher-order circular-azimuthal polarization

2021 ◽  
Vol 45 (3) ◽  
pp. 311-318
Author(s):  
V.V. Kotlyar ◽  
S.S. Stafeev
Keyword(s):  
Angular Momentum ◽  
Energy Flow ◽  
Focal Plane ◽  
Transverse Energy ◽  
Polarization Vector ◽  
Spin Angular Momentum ◽  
Local Maxima ◽  
New Type ◽  
Local Intensity ◽  
Transverse Energy Flow

Tight focusing of light with mth-order circular-azimuthal polarization was investigated. This is a new type of inhomogeneous hybrid polarization that combines the properties of mth order cylindrical polarization and circular polarization. Using the Richards-Wolf formalism, we obtained analytical expressions in the focal spot for the projections of the electric and magnetic field, the intensity distribution, the projections of the Poynting vector, and the spin angular momentum. It was shown theoretically and numerically that at the focus, the intensity has 2(m+1) local maxima located on a circle centered on an on-axis intensity null. It was shown that 4m vortices of a transverse energy flow were produced at the focus, with their centers located between the local intensity maxima. It was also shown that in the focal plane, the transverse energy flow changes the direction of rotation 2(2m+1) times around the optical axis. It is interesting that the longitudinal projection of the spin angular momentum at the focus changes sign 4m times. In those areas of the focal plane where the transverse energy flow rotates counterclockwise, the longitudinal projection of the spin angular momentum is positive, and the polarization vector rotates counterclockwise in the focal plane. Conversely, if the energy flow rotates clockwise, the polarization vector rotates clockwise, and the longitudinal projection of the spin angular momentum is negative. Numerical simulations are in agreement with the theoretical investigation.

scholarly journals Inversion of the axial projection of the spin angular momentum in the region of the backward energy flow in sharp focus

2020 ◽  
Vol 28 (23) ◽  
pp. 33830
Author(s):  
Victor V. Kotlyar ◽  
Anton G. Nalimov ◽  
Sergey S. Stafeev
Keyword(s):  
Angular Momentum ◽  
Energy Flow ◽  
Spin Angular Momentum ◽  
Sharp Focus

A FOURIER TRANSFORM APPROACH FOR TWO-CENTER OVERLAP-LIKE QUANTUM SIMILARITY INTEGRALS OVER SLATER TYPE ORBITALS

2004 ◽  
Vol 03 (02) ◽  
pp. 257-267 ◽  
Author(s):  
LILIAN BERLU
Keyword(s):  
Fourier Transform ◽  
Angular Momentum ◽  
Range Expansion ◽  
Expansion Method ◽  
Slater Type Orbitals ◽  
Quantum Similarity ◽  
Overlap Integrals ◽  
Slater Type ◽  
Transform Method ◽  
The Fourier Transform

In previous work,1 we presented a one center two range expansion method for the evaluation of the two-center overlap-like quantum similarity integrals over Slater type orbitals which are four orbitals overlap integrals. In this work, to improve the accuracy and to reduce the calculation times, the above integrals are developed using the Fourier transform approach and the so-called B functions. With the help of angular momentum selection rules, two-center overlap-like quantum similarity integrals are expressed as combinations of usual overlap integrals (e.g. two-orbitals) which could be evaluated very accurately using the Fourier transform method combinated with B functions.

scholarly journals Spin annihilations of and spin sifters for transverse electric and transverse magnetic waves in co- and counter-rotations

2014 ◽  
Vol 5 ◽  
pp. 1887-1898 ◽  
Author(s):  
Hyoung-In Lee ◽  
Jinsik Mok
Keyword(s):  
Wireless Communications ◽  
Energy Flow ◽  
Poynting Vector ◽  
Transverse Electric ◽  
Transverse Magnetic ◽  
Flow Density ◽  
Azimuthal Direction ◽  
Angular Momenta ◽  
Magnetic Waves

This study is motivated in part to better understand multiplexing in wireless communications, which employs photons carrying varying angular momenta. In particular, we examine both transverse electric (TE) and transverse magnetic (TM) waves in either co-rotations or counter-rotations. To this goal, we analyze both Poynting-vector flows and orbital and spin parts of the energy flow density for the combined fields. Consequently, we find not only enhancements but also cancellations between the two modes. To our surprise, the photon spins in the azimuthal direction exhibit a complete annihilation for the counter-rotational case even if the intensities of the colliding waves are of different magnitudes. In contrast, the orbital flow density disappears only if the two intensities satisfy a certain ratio. In addition, the concepts of spin sifters and enantiomer sorting are illustrated.

Introduction of spin torques

2017 ◽  
Author(s):  
T. Kimura
Keyword(s):  
Angular Momentum ◽  
Giant Magnetoresistance ◽  
Spontaneous Magnetization ◽  
Magnetic Domain ◽  
Magnetic Multilayers ◽  
Transfer Effect ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Angular Momentum ◽  
Spin Torques

This chapter discusses the spin-transfer effect, which is described as the transfer of the spin angular momentum between the conduction electrons and the magnetization of the ferromagnet that occurs due to the conservation of the spin angular momentum. L. Berger, who introduced the concept in 1984, considered the exchange interaction between the conduction electron and the localized magnetic moment, and predicted that a magnetic domain wall can be moved by flowing the spin current. The spin-transfer effect was brought into the limelight by the progress in microfabrication techniques and the discovery of the giant magnetoresistance effect in magnetic multilayers. Berger, at the same time, separately studied the spin-transfer torque in a system similar to Slonczewski’s magnetic multilayered system and predicted spontaneous magnetization precession.

scholarly journals Spin-decoupled metasurface for simultaneous detection of spin and orbital angular momenta via momentum transformation

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Yinghui Guo ◽  
Shicong Zhang ◽  
Mingbo Pu ◽  
Qiong He ◽  
Jinjin Jin ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Simultaneous Detection ◽  
Single Element ◽  
Single Shot ◽  
Single Spin ◽  
Dual Functional ◽  
Angular Momenta ◽  
Quadratic Phase ◽  
Mode Space ◽  
Optical Configuration

AbstractWith inherent orthogonality, both the spin angular momentum (SAM) and orbital angular momentum (OAM) of photons have been utilized to expand the dimensions of quantum information, optical communications, and information processing, wherein simultaneous detection of SAMs and OAMs with a single element and a single-shot measurement is highly anticipated. Here, a single azimuthal-quadratic phase metasurface-based photonic momentum transformation (PMT) is illustrated and utilized for vortex recognition. Since different vortices are converted into focusing patterns with distinct azimuthal coordinates on a transverse plane through PMT, OAMs within a large mode space can be determined through a single-shot measurement. Moreover, spin-controlled dual-functional PMTs are proposed for simultaneous SAM and OAM sorting, which is implemented by a single spin-decoupled metasurface that merges both the geometric phase and dynamic phase. Interestingly, our proposed method can detect vectorial vortices with both phase and polarization singularities, as well as superimposed vortices with a certain interval step. Experimental results obtained at several wavelengths in the visible band exhibit good agreement with the numerical modeling. With the merits of ultracompact device size, simple optical configuration, and prominent vortex recognition ability, our approach may underpin the development of integrated and high-dimensional optical and quantum systems.

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