Entangled states of orbital angular momentum of photons

Alois Mair

Anton Zeilinger

pp. 249-252

in: Daniel Greenberger, Anton Zeilinger (eds), Epistemological and experimental perspectives on quantum physics, Berlin, Springer, 1999

Abstract

Phase singularities exist in physical systems which can be described by a wave equation. Along a closed path C, the phase change is 2πm where m = ..−1, 0, +1, +2,.. is the winding number. For the case m ≠ 0 the path C encloses at least one phase singularity[l].