论文标题
BEC-BCS跨界的Ultracold Atomic Fermi超流体中的沉重极性物质：形式主义和应用
Heavy polarons in ultracold atomic Fermi superfluids at the BEC-BCS crossover: formalism and applications
论文作者
论文摘要
我们研究了从Bose-Einstein冷凝物（BEC）到跨界的成对两组分式费米气体中的重杂质的系统，该系统通过功能确定性方法（FDA）的扩展（FDA）。 FDA是一种精确的数值方法，用于研究Anderson \ Textquoteright S正交性灾难（OC）的表现，该灾难（OC）是沉浸在理想费米气体中的静态杂质系统中。在这里，我们将FDA扩展到由BCS平均场波函数描述的密切相关的超流体背景。与理想的费米气体情况相反，BCS超流体中的配对差距可阻止OC并导致频谱中的真正偏极信号。因此，我们确切的可解决模型可以更深入地了解极化物理。此外，我们发现偏振子频谱可用于测量超流体配对间隙，在磁性杂质的情况下，亚gap yu-shiba-rusinov（ysr）结合状态的能量。可以通过最先进的冷原子实验来检查我们的理论预测。
We investigate the system of a heavy impurity embedded in a paired two-component Fermi gas at the crossover from a Bose-Einstein condensate (BEC) to a Bardeen--Cooper--Schrieffer (BCS) superfluid via an extension of the functional determinant approach (FDA). FDA is an exact numerical approach applied to study manifestations of Anderson\textquoteright s orthogonality catastrophe (OC) in the system of a static impurity immersed in an ideal Fermi gas. Here, we extend the FDA to a strongly correlated superfluid background described by a BCS mean-field wavefunction. In contrast to the ideal Fermi gas case, the pairing gap in the BCS superfluid prevents the OC and leads to genuine polaron signals in the spectrum. Thus, our exactly solvable model can provide a deeper understanding of polaron physics. In addition, we find that the polaron spectrum can be used to measure the superfluid pairing gap, and in the case of a magnetic impurity, the energy of the sub-gap Yu-Shiba-Rusinov (YSR) bound state. Our theoretical predictions can be examined with state-of-art cold-atom experiments.
