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Comparing contact and dipolar interaction in a Bose-Einstein condensate

Axel Griesmaier·Jürgen Stuhler·Tobias Koch·Marco Fattori·Tilman Pfau·Stefano Giovanazzi
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Abstract

We have measured the relative strength $ε_dd$ of the magnetic dipole-dipole interaction compared to the contact interaction in a chromium Bose-Einstein condensate. We analyze the asymptotic velocities of expansion of a dipolar chromium BEC with different orientations of the atomic magnetic dipole moments. By comparing them with numerical solutions of the hydrodynamic equations for dipolar condensates, we are able to determine $ε_dd = 0.159\pm0.034$ with high accuracy. Since the absolute strength of the dipole-dipole interaction is known exactly, the relative strength of the dipoledipole interaction can be used to determine the s-wave scattering length $a = 5.08\pm1.06\cdot10^-9 m = 96\pm20 a0$ of 52Cr. This is fully consistent with our previous measurements on the basis of Feshbach resonances.

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Axel Griesmaier, Jürgen Stuhler, Tobias Koch, Marco Fattori, Tilman Pfau, Stefano Giovanazzi. 2006-08-07. Comparing contact and dipolar interaction in a Bose-Einstein condensate. https://doi.org/10.1103/physrevlett.97.250402

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