Spin precession in rubidium atoms is investigated through a pump–probe technique. The excited wave packet corresponds to a precession of spin and orbital angular momentum around the total angular momentum. We show that using shaped laser pulses allows us to control this dynamics. With a Fourier transform limited pulse, the wave packet is initially prepared in the bright state (coupled to the initial state) whereas a pulse presenting a π step in the spectral phase prepares the wave packet in the dark state (uncoupled to the initial state).
Voir en ligne : J. Phys. B : At. Mol. Opt. Phys. 41 (2008) 074023 (5pp)