Temporal coherent control induced by wave packet interferences in one and two photon atomic transitions |
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Authors: | MA Bouchene V Blanchet C Nicole N Melikechi B Girard H Ruppe S Rutz E Schreiber L Wöste |
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Institution: | Laboratoire de Collisions Agrégats Réactivité, C.N.R.S. (UMR 5589), IRSAMC, Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex, France, FR Freie Universit?t Berlin, Experimentalphysik, Arnimallee 14, 14169 Berlin, Germany, DE
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Abstract: | The interaction of a sequence of two identical ultrashort laser pulses with an atomic system results in quantum interferences
as in Ramsey fringes experiments. These interferences allow achievement of temporal coherent control of the excitation probability.
We present the results of a temporal coherent control experiment on two different atomic systems: one-photon absorption in
K (4s-4p) and two-photon absorption in Cs (6s-7d). In K, the quantum interferences between the two excitation paths associated with the laser pulses are revealed through
rapid oscillations of the excitation probability as a function of the time delay between the two pulses. These oscillations
take place at the transition frequency (period T = 2.56 fs). The interferences are modulated by beats (at about 580 fs) resulting from the doublet structure of the excited
state (4p (2
P
1/2
, 2
P
3/2
)). Three complementary interpretations of this experiment are presented: in terms of beats of quantum interferences, of variation
in the spectrum intensity, and of wave packet interferences. Whenever the two laser pulses are temporally overlapped, optical
interferences are superimposed on to the quantum interferences. The distinction between these two types of interference is
clearly revealed in the two-photon excitation scheme performed on Cs (6s-7d (2
D
3/2
, 2
D
5/2
)) because quantum interferences occur at twice the frequency of the optical interferences.
Received: 30 December 1997 / Revised: 28 February 1998 / Accepted: 4 March 1998 |
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Keywords: | PACS 32 80 Qk Coherent control of atomic interactions with photons - 32 80 Rm Multiphoton ionization and excitation to highly excited states (e g Rydberg states) - 42 50 Md Optical transient phenomena: quantum beats photon echo free-induction decay dephasings and revivals optical nutation and self-induced transparency |
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