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A: Atomphysik
A 2: Ultraschnelle Phänomene
A 2.5: Talk
Monday, March 16, 1998, 15:00–15:15, A702
Temporal coherent control by wave packet interferences in one and two photon atomic transitions — •E. Schreiber3, M.A. Bouchene1, V. Blanchet1, C. Nicole1, B. Girard1, H. Ruppe2, S. Rutz2, and L. Wöste2 — 1Laboratoire de Collisions Agrégats Réactivité, IRSAMC, Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 4, France — 2Freie Universität Berlin, Experimentalphysik, Arnimallee 14, D-14169 Berlin — 3Max-Born-Institut Berlin, Rudower Chaussee 6, D-12474 Berlin
Interaction of a two ultrashort laser pulses sequence with an atomic system result in quantum interferences. These interferences allow us to achieve temporal coherent control of the excitation cross section and will be presented for the K (4s-4p) one-photon transition in the weak field regime. Rapid oscillations (T=2.56 fs) at the transition frequency result from the quantum interferences between the two excitation paths. These interferences are modulated by beats (at 577 fs) resulting from the doublet structure of the excited state 4p (2P1/2, 2P3/2). We discuss three complementary interpretations of this experiment : in terms of beats of quantum interferences, in terms of wave packet interferences, and a spectral, time-independent interpretation. When the two laser pulses overlap, standard optical interferences take place. They exhibit similar features as the quantum interferences. Their different nature is well exhibited in the two photon transition Cs 6s-7d (2D3/2, 2D5/2) where the quantum interferences take place at the doubled frequency.