Griesmaier Axel, Stuhler Jürgen, Koch Tobias, Fattori Marco, Pfau Tilman, Giovanazzi Stefano
Physikalisches Institut, Universität Stuttgart, 70550 Stuttgart, Germany.
Phys Rev Lett. 2006 Dec 22;97(25):250402. doi: 10.1103/PhysRevLett.97.250402. Epub 2006 Dec 21.
We have measured the relative strength epsilon dd of the magnetic dipole-dipole interaction compared with the contact interaction in a dipolar chromium Bose-Einstein condensate. We analyze the asymptotic velocities of expansion of the condensate with different orientations of the atomic magnetic moments. By comparing the experimental results with numerical solutions of the hydrodynamic equations for dipolar condensates, we obtain epsilon dd = 0.159+/-0.034. We use this result to determine the s-wave scattering length a = (5.08+/-1.06 x 10(-9)) m = (96+/-20) a0 of 52Cr. This is fully consistent with our previous measurements on the basis of Feshbach resonances and therefore confirms the validity of the theoretical approach used to describe the dipolar Bose-Einstein condensate.
我们测量了在偶极铬玻色-爱因斯坦凝聚体中，与接触相互作用相比，磁偶极-偶极相互作用的相对强度εdd。我们分析了具有不同原子磁矩取向的凝聚体的渐近膨胀速度。通过将实验结果与偶极凝聚体的流体动力学方程的数值解进行比较，我们得到εdd = 0.159±0.034。我们利用这一结果确定了52Cr的s波散射长度a = (5.08±1.06×10⁻⁹) m = (96±20) a₀。这与我们之前基于费什巴赫共振的测量结果完全一致，因此证实了用于描述偶极玻色-爱因斯坦凝聚体的理论方法的有效性。
