A source and/or method of generating quantum-correlated and/or entangled photon
pairs using parametric fluorescence in a fiber Sagnac loop. The photon pairs are
generated in the 1550 nm fiber-optic communication band and detected by a detection
system including InGaAs/InP avalanche photodiodes operating in a gated Geiger mode.
A generation rate103 pairs/s is observed, a rate limited only
by available detection electronics. The nonclassical nature of the photon correlations
in the pairs is demonstrated. This source, given its spectral properties and robustness,
is well suited for use in fiber-optic quantum communication and cryptography networks.
The detection system also provides high rate of photon counting with negligible
after pulsing and associated high quantum efficiency and also low dark count rate.
