论文标题
Fermi Polaron重新访问：二极子分子过渡和共存
Fermi polaron revisited: polaron-molecule transition and coexistence
论文作者
论文摘要
我们使用良好的变分方法在三维（3D）费米子系统中重新审视二极化的分子转变。发现该分子在最低的粒子孔激发上本质上不稳定，并且在强耦合方面，它只能近似具有有限的总动量的杂质系统的基态。因此，可以将二极化 - 分子转变重新解释为具有不同总成绩的单个杂质系统之间的一阶转变。在过渡附近的某些交互窗口中，两个状态在分散曲线中以局部最小值的形式出现，表明它们可以在现实的系统中共存。我们进一步证实了在存在有限的杂质浓度的情况下并且在低温下的二极子分子共存，这直接导致光滑的二极化 - 分子转变，如最近3D超低费米气体的实验中所观察到的。我们的结果为北极子和分子之间的竞争和转化提供了明确的物理图片，并阐明了低维度的费米极化物特性。
We revisit the polaron-molecule transition in three-dimensional(3D) fermion systems using the well-established variational approach. The molecule is found to be intrinsically unstable against lowest-order particle-hole excitations, and it can only approximate the ground state of impurity system with finite total momentum in the strong coupling regime. The polaron-molecule transition can therefore be reinterpreted as a first-order transition between single impurity systems with different total momenta. Within certain interaction window near their transition, both states appear as local minima in the dispersion curve, indicating they can coexist in a realistic system. We have further confirmed the polaron-molecule coexistence in the presence of a finite impurity concentration and at low temperature, which directly leads to a smooth polaron-molecule transition as observed in recent experiments of 3D ultracold Fermi gases. Our results have provided an unambiguous physical picture for the competition and conversion between polaron and molecule, and also shed light on Fermi polaron properties in low dimensions.
