Quantum entangled photons, which are usually created via optical nonlinearity, have a unique correlation between them. This paper describes entangled-photon generation using spontaneous four-wave mixing in fiber and its application to quantum cryptography.
Summary form only given. Correlated and entangled single photon states have made possible many fundamental studies in quantum optics such as the Bell-type test of hidden variables and non-locality, explorations of quantum interference properties, and investigations of quantum information processing and quantum communications technologies such as quantum cryptography, quantum computing, and quantum teleportation. These correlated single photon states are traditionally generated via a spontaneous parametric down-conversion process using a /spl chi//sup (2)/ material. We propose and analyze the generation of entangled single photons using /spl chi//sup (2)/ parametric processes in optical fibers. Such processes provide a simple and inexpensive correlated photon source readily compatible with commercial communications technologies. It further affords high efficiency for coupling into single mode fibers for applications in quantum cryptography.
Quantum laws can be used to implement secure communication channels; this has been named quantum cryptography. In quantum cryptography the security does not depend of limited computational power, but is inherent to the laws that govern the propagation and detection of single and entangled photons. We show how single and entangled photon-pairs can be efficiently generated using four-wave mixing in optical fibers. We analyze the source statistics, degree of entanglement and impact of spontaneous Raman scattering. By coding information in the photons polarization we are able to transmit quantum information over 20 km of standard single mode fiber.