Hyper-entangled states and free-space quantum cryptography
Alexander V. Sergienko, Mete Atatüre, Giovanni Di Giuseppe, Gregg S. Jaeger, Bahaa E. A. Saleh, Malvin Carl Teich · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2002
We describe the development of a quantum key distribution (QKD) scheme based on ultrafast laser pumped sources of entangled photon pairs and the engineering of their entanglement properties. Though quantum entanglement has been shown to be a useful resource for quantum key distribution, little work has been carried out in making use of the full range of joint entanglement behavior present in hyper-entangled photon pairs. We consider the principal advantages of our QKD scheme in connection with the way it makes use of ultrafast laser pumped spontaneous parametric down-conversion and hyper-entanglement. In particular, we consider how polarization quantum interference may be modified by manipulating the spatial features of the down-converted light.