The photomagneton is a theoretical treatment of the unitary group in

quantum field theory In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines classical field theory, special relativity, and quantum mechanics. QFT is used in particle physics to construct physical models of subatomic particles and ...

and

quantum chemistry Quantum chemistry, also called molecular quantum mechanics, is a branch of physical chemistry focused on the application of quantum mechanics to chemical systems, particularly towards the quantum-mechanical calculation of electronic contributions ...

that effectively describes the experimentally observed inverse Faraday effect. When circularly polarized light travels through a plasma, the angular momentum associated to the circular motion of the photons induces an angular momentum in the electrons of the plasma. This angular momentum induces an associated

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

. Exactly how this happens remains a subject of debate. For instance, if the so-called ghost field does not contribute to the free electromagnetic energy density in the plasma, then the electron must couple to something like a complex electric field. However, if the field induces a finite magnetic field in the absence of matter, then the implication may be a finite photon rest mass.

References

A. Hasanein and M. Evans, ''The Photomagneton and Quantum Field Theory: Vol. 1 of Quantum Chemistry,'' World Scientific, 1994 Quantum field theory Magneto-optic effects {{quantum-stub