エキゾティック原子の量子気体の理論

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During this year, I improved the numerical methods for describing the dynamics of ultracold dipolar Fermi gases and obtained compelling new results regarding the Einstein-de Haas effect in such systems. This was necessary because the first results I had obtained turned out to be flawed by unexpected artifacts, therefore I meticulously identified all sources of numerical errors and developed measures to overcome them. With the resulting improved numerical setup, I studied the dynamics of two-dimensional dipolar Fermi gases with two spin components, focussing on the so-called Einstein-de Haas (EdH) Effect, the transfer of magnetization into orbital angular momentum. My results show that in a Fermi gas, the EdH effect appears together with an additional process, a twisting motion, where both spin components rotate in opposite directions with considerably larger individual angular momenta than the full system. Using energy functionals I found out that this is the result of Fermi surface deformation, induced by the anisotropic dipole-dipole interactions and therefore absent in a BEC. A main consequence of this twisting motion is that the EdH effect might be easier to detect experimentally in a Fermi gas. A second feature of this twisting motion is its sensitivity to changes in the s-wave scattering length or an external magnetic field, which can lead to a reversal of the relative rotation. This could prove very useful for experimental research of ultracold dipolar gases such as Dysprosium, where the values of s-wave scattering lengths remain unknown so far.