Darmstadt 2008 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 26: Poster Ultrakurze Laserpulse

Q 26.11: Poster

Dienstag, 11. März 2008, 16:30–19:00, Poster C1

Resonant strong-field control of potassium atoms by spectral θ-step phase modulation — •Tim Bayer, Matthias Wollenhaupt, and Thomas Baumert — Universität Kassel, Institut für Physik und CINSaT, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany

Selective Population of Dressed States (SPODS) is the key to coherent control of resonant quantum phenomena in strong laser fields. Recently two SPODS control schemes have been devised which make use of shaped femtosecond laser pulses [1,2]. It was shown that chirped pulses as well as pulse sequences can be used to steer potassium atoms into single dressed states, achieving high efficiency and selectivity. The underlying control mechanisms are based on continuously varying temporal phases (adiabatic SPODS) and discrete temporal phase jumps (non-adiabatic SPODS) respectively. Here, we employ a spectral phase modulation function of the form ϕ(ω)=θ/2·σ(ω−δω), where σ denotes the signum function, which produces a double pulse structure in time with a linearly varying phase and a phase jump in between the two pulses. Hence, this pulse shape combines adiabatic with non-adiabatic aspects. We present measured photoelectron spectra from resonant multi-photon ionization of potassium atoms as a function of the spectral step size θ and the detuning δω. Our results show, that both parameters provide an efficient means to exert control on the dressed state populations.

[1] M. Wollenhaupt et al.: PRA 73, 2006

[2] M. Wollenhaupt et al.: APB 82, 2006