A Large-alphabet Quantum Key Distribution Protocol Using Orbital Angular Momentum Entanglement
Sheng-Mei Zhao, Long-Yan Gong, Yong-Qiang Li, Hua Yang, Yu-Bo Sheng, Wei-Wen Cheng · Chinese Physics Letters · 2013
We experimentally demonstrate a quantum key distribution protocol using entangled photon pairs in orbital angular momentum (OAM). Here Alice uses a fixed phase hologram to modulate her OAM state on one photon with a spatial light modulator (SLM), while Bob uses the designed N different phase holograms for his N-based keys on the other photon with his SLM. With coincidences, Alice can fully retrieve the keys sent by Bob without reconciliation. We report the experiment results with N = 3 and OAM eigenmodes |ℓ = ±1〉, and discuss the security from the light path and typical attacks.