Spin of Photons: Nature of Polarisation

Fuente: arXiv
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Autore principale: Saito, Shinichi
Natura: Preprint
Pubblicazione: 2023
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author Saito, Shinichi
author_facet Saito, Shinichi
contents Stokes parameters (${\bf S}$) in Poincaré sphere are very useful values to describe the polarisation state of photons. However, the fundamental principle of the nature of polarisation is not completely understood, yet, because we have no concrete consensus how to describe spin of photons, quantum-mechanically. Here, we have considered a monochromatic coherent ray of photons, described by a many-body coherent state, and tried to establish a fundamental basis to describe the spin state of photons, in connection with a classical description based on Stokes parameters. We show that a spinor description of the coherent state is equivalent to Jones vector for polarisation states, and obtain the spin operators (${\bf \hat{S}}$) of all components based on rotators in a $SU(2)$ group theory. Polarisation controllers such as phase-shifters and rotators are also obtained as quantum-mechanical operators to change the phase of the wavefunction for polarisation states. We show that the Stokes parameters are quantum-mechanical average of the obtained spin operators, ${\bf S} = \langle {\bf \hat{S}} \rangle $.
format Preprint
id arxiv_https___arxiv_org_abs_2303_17112
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Spin of Photons: Nature of Polarisation
Saito, Shinichi
Optics
Quantum Physics
Stokes parameters (${\bf S}$) in Poincaré sphere are very useful values to describe the polarisation state of photons. However, the fundamental principle of the nature of polarisation is not completely understood, yet, because we have no concrete consensus how to describe spin of photons, quantum-mechanically. Here, we have considered a monochromatic coherent ray of photons, described by a many-body coherent state, and tried to establish a fundamental basis to describe the spin state of photons, in connection with a classical description based on Stokes parameters. We show that a spinor description of the coherent state is equivalent to Jones vector for polarisation states, and obtain the spin operators (${\bf \hat{S}}$) of all components based on rotators in a $SU(2)$ group theory. Polarisation controllers such as phase-shifters and rotators are also obtained as quantum-mechanical operators to change the phase of the wavefunction for polarisation states. We show that the Stokes parameters are quantum-mechanical average of the obtained spin operators, ${\bf S} = \langle {\bf \hat{S}} \rangle $.
title Spin of Photons: Nature of Polarisation
topic Optics
Quantum Physics
url https://arxiv.org/abs/2303.17112