  This paper reports 1.5-um band time-bin entanglement generation. We employed
a spontaneous four-wave mixing process in a dispersion shifted fiber, with
which correlated photon pairs with very narrow bandwidths were generated
efficiently. To observe two-photon interference, we used planar lightwave
circuit based interferometers that were operated stably without feedback
control. As a result, we obtained coincidence fringes with 99 % visibilities
after subtracting accidental coincidences, and successfully distributed
entangled photons over 20-km standard single-mode fiber without any
deterioration in the quantum correlation.
