State-selective excitation of alkali-metal atoms by the phase control in the strong laser field

Yokoyama, Keiichi  ; Sugita, Akihiro; Teranishi, Yoshiaki*; Itakura, Ryuji; Matsuoka, Leo; Yokoyama, Atsushi

State-selective excitation of atomic cesium and potassium to their spin-orbit states, Cs(7D-6S) and K(4P-4S), are carried out by a coherent quantum control technique. In the weak field regime, ultrafast and highly selective excitation of cesium atoms has been successfully demonstrated with a pair of identical transform-limited pulses in which the control parameter is the phase difference between the two pulses alone. However, the excitation probability is very small (0.001) due to the weak laser field. To perform the selective excitation with large excitation probability (1), one-photon process of the K(4P-4S) transition is examined. The excitation probability is expected to become large while the selectivity degrades if the control parameter is the phase difference alone. The obtained laser intensity dependence agrees well with the theoretical prediction, indicating the excitation indeed in the non-perturbative regime.