SYNCHRONIZATION OF QUANTUM TRANSITIONS BY THE COHERENT INTERACTION OFULTRASHORT ELECTROMAGNETIC PULSES WITH MULTILEVEL QUANTUM-SYSTEMS

If the spectral width of the pulse is sufficiently wide, the coherent interaction between the pulse and a multilevel medium becomes possible . For the multilevel configuration, it was shown that the level popula tion depends on the time between pulses as a superposition of harmonic oscillations with frequencies of fine (hyperfine) structures. This co nfirmation is illustrated by an example of five-level configuration of Rb. It is useful for the creation of new time and frequency standards , and for their direct precision measurements. The first obtained expe rimental results on stabilization of the pulse repetition frequency sh owed that the stability of the repetition frequency of femtosecond Ti :Al2O3 laser pulses was at least 2 x 10(-10) in 100 s.