Observation of Coherent Transients in Ultrashort Chirped Excitation of an Undamped Two-Level System

Sébastien Zamith (1, 2) , Jérôme Degert (1, 2) , Sabine Stock (1, 2) , Béatrice de Beauvoir (1, 2) , Valérie Blanchet (1, 2) , M. A. Bouchene (1, 2) , Bertrand Girard (1, 2)

1 Femto (LCAR)
2 LCAR - Laboratoire Collisions Agrégats Réactivité

The effects of coherent excitation of a two-level system with a linearly chirped pulse are studied theoretically and experimentally [in Rb ( 5s-5p)] in the low field regime. The coherent transients are measured directly on the excited state population on an ultrashort time scale. A sharp step corresponds to the passage through resonance. It is followed by oscillations resulting from interferences between off-resonant and resonant contributions. We finally show the equivalence between this experiment and Fresnel diffraction by a sharp edge.

Domaines: Physique [physics]

Sébastien Zamith, Jérôme Degert, Sabine Stock, Béatrice de Beauvoir, Valérie Blanchet, et al.. Observation of Coherent Transients in Ultrashort Chirped Excitation of an Undamped Two-Level System. Physical Review Letters, 2001, 87, pp.033001. ⟨10.1103/PhysRevLett.87.033001⟩. ⟨hal-00005047⟩