What is actually the spin of Photon

In quantum mechanics, a photon’s “spin” refers to its intrinsic angular momentum, which is directly related to its polarization state, meaning that a photon’s polarization is essentially its “spin” manifested as a property of light waves; a photon can be either right-circularly polarized (spin +1) or left-circularly polarized (spin -1), with linear polarization being a superposition of these two states. 

Key points about photon spin and polarization:

• Spin as a fundamental property:Like other particles, a photon has an intrinsic angular momentum called “spin” which is a quantum mechanical property. 
• Polarization and spin connection:For a photon, its polarization state directly corresponds to its spin. 
• Circular polarization and spin:A photon with right circular polarization has a spin of +1, while a left circularly polarized photon has a spin of -1. 
• Linear polarization and spin:Linear polarization can be considered as a superposition of equal amounts of left and right circular polarization, resulting in a “zero spin” state. 

Important to note:

• Not like classical rotation:While we often think of “spin” as a particle rotating around an axis, a photon’s spin is a quantum mechanical property and doesn’t correspond to a physical rotation in the classical sense. 
• Measuring polarization:By measuring the polarization of light, you can effectively determine the spin of the photons within that beam.