Coherent manipulation of four-level double lambda-like atomic system by   a train of ultra-short few-cycle-optical pulses
  We have demonstrated that near complete coherence can be achieved in a four level double lambda-like systems using a train of ultra-short optical pulses. The effect of the Doppler broadening has been analyzed and a scheme has been proposed for establishing high and uniform coherence across different velocity groups in the atomic ensemble. We have also presented a novel scheme of excitation using chirped pulses and shown that in addition to generating coherence in the system it is possible to alter the translational states of the atoms. 
Pawan Kumar and Amarendra K. Sarma
physics.optics physics.atom-ph quant-ph