  A scheme for entangling distant atoms is realized, as proposed in the seminal
paper by Cabrillo et al. [Phys. Rev. A 59, 1025 (1999)]. The protocol is based
on quantum interference and detection of a single photon scattered from two
effectively one meter distant laser-cooled and trapped atomic ions. The
detection of a single photon heralds entanglement of two internal states of the
trapped ions with high rate and with a fidelity limited mostly by atomic
motion. Control of the entangled state phase is demonstrated by changing the
path length of the single-photon interferometer.
