  In this letter, we report an experimental realization of distributing
entangled photon pairs over 100 km of dispersion-shifted fiber. In the
experiment, we used a periodically poled lithium niobate waveguide to generate
the time-energy entanglement and superconducting single-photon detectors to
detect the photon pairs after 100 km. We also demonstrate that the distributed
photon pairs can still be useful for quantum key distribution and other quantum
communication tasks.
