Quasi-Intrinsic Angular Momentum and the Measurement of Its Spectrum
Zambrini, Roberta; Barnett, Stephen M.
Physical Review Letters 96, 113901 (1-4) (2006)
We introduce the concept of quasi-intrinsic angular momentum to denote fields for which the mean
value of the angular momentum is unaltered by a lateral shift of the rotation axis but the spectrum changes. This property is exemplified by the orbital angular momentum of a beam of light about its propagation direction. We propose an interferometric experiment to measure efficiently the exact angular momentum
spectrum and variance for light beams with any arbitrary spatial distribution.