Osnabrück 2002 – wissenschaftliches Programm
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Q: Quantenoptik
Q 433: Poster: Laser – Grundlagen und Anwendungen
Q 433.13: Poster
Donnerstag, 7. März 2002, 16:30–18:30, Schloss
Light shift of excited states of Cesium in a dipole trap — •Wolfgang Alt, Dominik Schrader, Stefan Kuhr, Igor Dotsenko, Yevhen Miroshnychenko, Victor Gomer, and Dieter Meschede — Institut für Angewandte Physik, Wegelerstr. 8, 53115 Bonn
We measure the Zeeman resolved light shift of the Cs excited state in a dipole trap and compare it to a numerical calculation. A small number of Cs atoms in a Nd:YAG optical dipole trap is illuminated by a weak probe laser. The probe laser frequency is scanned over the 62S1/2 − 62P3/2-transition at 852 nm, while the fluorescence is recorded.
The AC-Stark splitting of the transition is clearly resolved in the spectra. The light shifts of the Zeeman sublevels in the excited states vary both in magnitude and sign, whereas the degeneracy of the ground state is not lifted for linearly polarized dipole traps. This leads to a strong dependency of the fluorescence spectra on the probe laser polarization.
A numerical calculation of the AC-Stark shift, taking into account about 10 higher levels, agrees well with the measurements. It allows the determination of "magic dipole trap wavelenghts", where, depending on dipole trap polarisations, the light shift of certain transitions vanishes.
The main difference between ion and neutral atom traps is the dependence of the trapping potential on the internal state of the atom. This AC-Stark splitting of the levels is important for state selective detection and manipulation of neutral atoms in optical dipole traps.