Generation of arbitrary Fock states via resonant interactions in cavity   QED
  We propose a scheme to generate arbitrary Fock states |N> in a cavity QED using N resonant Rydberg atoms. The atom-field interaction times are controlled via Stark-shifts adjusted in a way that each atom transfers a photon to the cavity, turning atomic detections useless. Fluctuations affecting the control of the atom-field interactions are also considered. 
Gisana C. A. Bueno, W. B. Cardoso, A. T. Avelar, and B. Baseia