Detection of superposition in the orbital angular momentum of photons without excess components and its application in the verification of non-classical correlation

摘要

Orbital angular momentum states (Laguerre-Gaussian modes) of photons are attracting attention for realizing a high-dimensional quantum space, and several experimental verifications of entanglement have been reported. Some of these experiments measure photons in the superposition of different azimuthal modes by shifting the hologram dislocation. But this method has the problem that various unneeded azimuthal modes mix in the measurement basis. In order to solve this problem, we propose a new method using a hologram and a path interferometer. We also report an experimental observation of non-classical correlation in the orbital angular momentum of photons by use of the proposed method.