论文标题
超低费米气体中的非热磁性
Non-Hermitian Ferromagnetism in an Ultracold Fermi Gas
论文作者
论文摘要
我们为激发分支中排斥相互作用的费米气体开发了一种非热有效理论。壳上的$ t $ -matrix用作复杂值的相互作用项，该项描述了激发分支中原子与有吸引力分支的两体无弹性衰减之间的排斥相互作用。要查看该模型的特征，我们已经在弱耦合方面解决了排斥性费米极性偏极的激发特性以及时间依赖性的数量密度。这些数量获得的分析表达式在定性上与最近的实验达成了良好的一致性。通过计算随机相近似中的动态横向自旋敏感性，我们表明具有非零极化的铁磁系统会发生动力不稳定性，并且倾向于异质相。
We develop a non-Hermitian effective theory for a repulsively interacting Fermi gas in the excited branch. The on-shell $T$-matrix is employed as a complex-valued interaction term, which describes a repulsive interaction between atoms in the excited branch and a two-body inelastic decay to the attractive branch. To see the feature of this model, we have addressed, in the weak coupling regime, the excitation properties of a repulsive Fermi polaron as well as the time-dependent number density. The analytic expressions obtained for these quantities qualitatively show a good agreement with recent experiments. By calculating the dynamical transverse spin susceptibility in the random phase approximation, we show that a ferromagnetic system with nonzero polarization undergoes a dynamical instability and tends towards a heterogeneous phase.
