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In all BECs realized so far, the dominant interaction stems from the isotropic contact potential due to s--wave scattering. Many new interesting features are predicted for a BEC where anisotropic, long-range interactions like the dipole--dipole interaction become important [1]. An ideal candidate for observing effects of the magnetic dipole interaction is atomic chromium with a large magnetic moment of 6 B. Currently achievable phase space densities in our crossed optical dipole trap are above 0.1.
We present the progress towards a quantum degenerate gas of chromium atoms and report on our recent determination of the sign and the magnitude of the s- wave scattering length of Cr atoms [2], the investigation of the dipolar relaxation processes in a magnetically trapped chromium gas [3] and a detailed study of Feshbach resonances in Chromium. [1] see for example: Stefano Giovanazzi, Axel Görlitz, and T. Pfau, Phys. Rev. Lett. 89, 130401 (2002) and references therein [2] P. Schmidt, S. Hensler, J. Werner, A. Griesmaier, A. Görlitz, T. Pfau, and A. Simoni, Phys. Rev. Lett. 91, 193201 (2003) [3] S. Hensler, J. Werner, A. Griesmaier, P.O. Schmidt, A. Görlitz, T. Pfau, S. Giovanazzi, K. Rzazewski, Appl. Phys. B 77, 765-772 (2003) |