论文标题
平坦带Bose-Einstein冷凝水的繁殖力重新审视
Supefluidity of flat band Bose-Einstein condensates revisited
论文作者
论文摘要
我们考虑了多型Bogoliubov理论中平坦带玻色的凝结物（BEC）的超流量，声音的速度和激发部分。超流量的重量是通过引入相绕组并将自由能相对于它最小化而计算得出的。我们发现，超流体重量是由于冷凝水密度和化学潜力的变化而产生的，这是对先前文献中忽略的相位扭曲的变化。我们还指出，声音速度和激发部分与量子度量和量子距离的轨道位置非依赖性的概括成正比，仅在特殊情况下仅在特殊情况下仅降低到通常的量子指标（fubini-study Metric）和Hilbert-Schmidt量子。我们得出了二阶扰动校正对声音速度对广义量子度量的依赖性的校正，并表明它与数值计算很好地比较。我们的结果提供了平坦的BEC和量子几何形状之间的一致联系，并且物理可观察的物体独立于轨道位置，并完整的公式用于评估Bogoliubov理论中的超流体重量。我们讨论了Bogoliubov理论在评估超流量重量时的局限性。
We consider the superfluid weight, speed of sound and excitation fraction of a flat band Bose-Einstein condensate (BEC) within multiband Bogoliubov theory. The superfluid weight is calculated by introducing a phase winding and minimizing the free energy with respect to it. We find that the superfluid weight has a contribution arising from the change of the condensate density and chemical potential upon the phase twist that has been neglected in the previous literature. We also point out that the speed of sound and the excitation fraction are proportional to orbital-position-independent generalizations of the quantum metric and the quantum distance, and reduce to the usual quantum metric (Fubini-Study metric) and the Hilbert-Schmidt quantum distance only in special cases. We derive a second order perturbation correction to the dependence of the speed of sound on the generalized quantum metric, and show that it compares well with numerical calculations. Our results provide a consistent connection between flat band BEC and quantum geometry, with physical observables being independent of the orbital positions as they should, and complete formulas for the evaluation of the superfluid weight within the Bogoliubov theory. We discuss the limitations of the Bogoliubov theory in evaluating the superfluid weight.
