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The tuning of atom pair interaction by means of magnetic fields has been proven to be of tremendous help for fundamental research. However, its variability is limited: The interaction within the whole ensemble is effected simultaneously and similarly. Also, frequency standard experiments may ask for a BEC of the clock element in a preparation step, e.g., to efficiently load an optical lattice. Here, the scattering length cannot be tuned by magnetic fields, but laser fields may allow for selecting a scattering length arbitrarily.
In a molecular beam experiment, we have demonstrated such a laser induced manipulation for the example of two sodium atoms, one atom being in the ground state, and the other in an excited state. We also developed a quantitative description, which confirms our observations [1]. Of course, the manipulation of the interaction of two ground state atoms is of much higher interest. In a second, similar experiment, we give a proof of concept for the laser induced manipulation of two ground state atoms. But, in order to verify the validity of a quantitative model for this case, we simulate in detail line shapes, but full agreement with experimental observations is not yet obtained. Good interaction potentials should soon allow for predictions of the scattering length depending on frequency and intensity of a manipulation laser. [1] Chr. Samuelis et.al.: Eur. Phys. J. D 26, 307 (2003) |