Measurement of Optical Orbital and Spin Angular Momentum: Implications for Photon Angular Momentum

摘要

The expression for the total angular momentum carried by a laser opticalvortex beam, splits, in the paraxial approximation, into two terms which seemto represent orbital and spin angular momentum respectively. There are,however, two very different competing versions of the formula for the spinangular momentum, one based on the use of the Poynting vector, as in classicalelectrodynamics, the other related to the canonical expression for the angularmomentum which occurs in Quantum Electrodynamic. I analyze the possibility thata sufficiently sensitive optical measurement could decide which of thesecorresponds to the actual physical angular momentum carried by the beam.