scholarly journals The angular momentum of vectorial non-paraxial fields and the role of radial charges in orbit-spin coupling

2020 ◽  
Vol 238 ◽  
pp. 12017
Author(s):  
Omar El Gawhary ◽  
Paul Urbach

Electromagnetic fields carry a linear and an angular momentum, the first being responsible for the existence of the radiation pressure and the second for the transfer of torque from electromagnetic radiation to matter. The angular momentum is considered to have two components, one due to the polarization state of the field, usually called Spin Angular Momentum (SAM), and one due to existence of topological azimuthal charges in the field phase profile, which leads to the Orbital Angular Momentum (OAM). For non-paraxial fields these two contributions are not independent of each other, something which is described as spin-orbit coupling. It has been recently proved that electromagnetic fields necessarily carry also invariant radial charges that, as discussed in this work, play a key role in the angular momentum. Here we show that the total angular momentum consists in fact of three components: one component only dependent on the spin of the field, another dependent on the azimuthal charges carried by the field and a third component dependent on the spin and the radial charges contained in the field. By properly controlling the number and coupling among these radial charges it is possible to design electromagnetic fields with a desired total angular momentum. In this way it is also possible to discover fields with no orbital angular momentum and a spin angular momentum typical of spin-3/2 objects, irrespective of the fact that photons are spin-1 particles.

Author(s):  
ShaoXu Ren

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.


2022 ◽  
Author(s):  
Pengtao Lai ◽  
Zenglin Li ◽  
Wei Wang ◽  
Jia Qu ◽  
Liang Wei Wu ◽  
...  

Abstract Coding metasurfaces have attracted tremendous interests due to unique capabilities of manipulating electromagnetic wave. However, archiving transmissive coding metasurface is still challenging. Here we propose a transmissive anisotropic coding metasurface that enables the independent control of two orthogonal polarizations. The polarization beam splitter and the OAM generator have been studied as typical applications of anisotropic 2-bit coding metasurface. The simulated far field patterns illustrate that the x and y polarized electromagnetic waves are deflected into two different directions, respectively. The anisotropic coding metasurface has been experimentally verified to realize an orbital angular momentum (OAM) beam with l = 2 of right-handed polarized wave, resulting from both contributions from linear-to-circular polarization conversion and the phase profile modulation. This work is beneficial to enrich the polarization manipulation field and develop transmissive coding metasurfaces.


2008 ◽  
Vol 77 (12) ◽  
pp. 124201 ◽  
Author(s):  
Giovanni Fazio ◽  
Giorgio Giardina ◽  
Francis Hanappe ◽  
Giuseppe Mandaglio ◽  
Marina Manganaro ◽  
...  

2020 ◽  
Vol 35 (18) ◽  
pp. 2050084
Author(s):  
Taeseung Choi

We have revisited the Dirac theory in [Formula: see text] and [Formula: see text] dimensions by using the covariant representation of the parity-extended Poincaré group in their native dimensions. The parity operator plays a crucial role in deriving wave equations in both theories. We studied two position operators, a canonical one and a covariant one that becomes the particle position operator projected onto the particle subspace. In [Formula: see text] dimensions the particle position operator, not the canonical position operator, provides the conserved Lorentz generator. The mass moment defined by the canonical position operator needs an additional unphysical spin-like operator to become the conserved Lorentz generator in [Formula: see text] dimensions. In [Formula: see text] dimensions, the sum of the orbital angular momentum given by the canonical position operator and the spin angular momentum becomes a constant of motion. However, orbital and spin angular momentum do not conserve separately. On the other hand the orbital angular momentum given by the particle position operator and its corresponding spin angular momentum become a constant of motion separately.


2019 ◽  
Vol 9 (13) ◽  
pp. 2600 ◽  
Author(s):  
Yang Yue ◽  
Hao Huang ◽  
Yongxiong Ren ◽  
Zhongqi Pan ◽  
Alan E. Willner

It is well-known now that angular momentum carried by elementary particles can be categorized as spin angular momentum (SAM) and orbital angular momentum (OAM) [...]


2018 ◽  
Vol 26 (13) ◽  
pp. 17227 ◽  
Author(s):  
Tao Zhang ◽  
Yi-Dong Liu ◽  
Kuo Yang ◽  
Jiandong Wang ◽  
Pusheng Liu ◽  
...  

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