  A novel method for preparation of a single photon in temporally-delocalized
entangled modes is proposed and analyzed. We show that two single-photon pulses
propagating in a driven nonabsorbing medium with different group velocities are
temporally split under parametric interaction into well-separated pulses. In
consequence, the single-photon "time-bin-entangled" states are generated with a
programmable entanglement easily controlled by driving field intensity. The
experimental study of nonclassical features and nonlocality of generated states
by means of balanced homodyne tomography is discussed.
