  Single photon source is one of the key devices for optical quantum
information processing. Differing from the usual stimulated Raman adiabatic
passage to obtain single-photon radiation, here we propose an approach to
produce optical Fock state on demand in the usual atom-cavity system by
utilizing the technique of transitionless quantum driving. The present proposal
effectively suppresses the unwanted but practically unavoidable nonadiabatic
transitions in the previous adiabatic schemes. Therefore, the efficiency of
Fock state production by the present technique could be significantly high,
even in the presence of various atomic and cavity dissipations.
