We demonstrate distribution of polarization entangled photons over 100 km of optical fiber. Measurements of the two-photon visibility, without dark count subtraction, have shown that the quantum correlations (raw visibility 89%) allow secure quantum cryptography after 100 km of non-zero dispersion shifted fiber using commercially available single photon detectors. In addition, quantum tomography has revealed little degradation of entangled state indicating minimal loss in fidelity during the transmission.
© 2007 Optical Society of America
(060.0060) Fiber optics and optical communications : Fiber optics and optical communications
(060.2330) Fiber optics and optical communications : Fiber optics communications
(270.0270) Quantum optics : Quantum optics
(270.4180) Quantum optics : Multiphoton processes
M. R. Vanner, H. Hübel, A. Poppe, and A. Zeilinger, "Polarization Entanglement over 100 km Optical Fiber for Quantum Key Distribution," in Quantum-Atom Optics Downunder, OSA Technical Digest (CD) (Optical Society of America, 2007), paper QME26.
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