  A quantum repeater at telecommunications wavelengths with long-lived atomic
memory is proposed, and its critical elements are experimentally demonstrated
using a cold atomic ensemble. Via atomic cascade emission, an entangled pair of
1530 nm and 780 nm photons is generated. The former is ideal for long-distance
quantum communication, and the latter is naturally suited for mapping to a
long-lived atomic memory. Together with our previous demonstration of
photonic-to-atomic qubit conversion, both of the essential elements for the
proposed telecommunications quantum repeater have now been realized.
