New Journal of Physics
Interferometric measurement of the helical mode of a single photon
Enrique J. Galvez, Laura E. Coyle, Eric G. Johnson, Benjamin J. Reschovsky
Abstract
We present measurements of the helical mode of single photons and do so by sending heralded photons through a Mach–Zehnder interferometer that prepares the light in a helical mode with topological charge one, and interferes it with itself in the fundamental non-helical mode. Masks placed after the interferometer were used to diagnose the amplitude and phase of the mode of the light. Auxiliary measurements verified that the light was in a non-classical state. The results are in good agreement with theory. The experiments demonstrate in a direct way that single photons carry the entire spatial helical-mode information.