Abstract
We calculate analytically the spin-orbital decomposition of the angular momentum using completely nonparaxial fields that have a certain degree of linkage of electric and magnetic lines. The split of the angular momentum into spin-orbital components is worked out for non-null knotted electromagnetic fields. The relation between magnetic and electric helicities and spin-orbital decomposition of the angular momentum is considered. We demonstrate that even if the total angular momentum and the values of the spin and orbital momentum are the same, the behavior of the local angular momentum density is rather different. By taking cases with constant and non-constant electric and magnetic helicities, we show that the total angular momentum density presents different characteristics during time evolution.
Highlights
There has been recently some interest in the orbital-spin decomposition of the angular momentum carried by light
The total angular momentum can be decomposed into orbital and spin angular momenta for paraxial light, but for nonparaxial fields, that splitting is more controversial because their quantized forms do not satisfy the commutation relations [1,2]
We provide an example of each case and plot the time evolution of the total angular momentum density
Summary
There has been recently some interest in the orbital-spin decomposition of the angular momentum carried by light. We compute the orbital-spin contributions to the total angular momentum analytically for a knotted class of fields [5] These fields have nontrivial electromagnetic helicity [6,7]. We show that the existence of electromagnetic fields in a vacuum with the same constant angular momentum and orbital-spin decomposition, but different electric and magnetic helicities is possible. We will get some general results, such as the difference between the magnetic and electric spin components in the Coulomb gauge is null. This conclusion coincides with the results found, for example, in [46] using a different approach.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
