论文标题
在二维中对费米极化问题问题的有效变异方法，无论是在均衡的范围内还是超出平衡
Efficient variational approach to the Fermi polaron problem in two dimensions, both in and out of equilibrium
论文作者
论文摘要
我们开发了一种非高斯变化方法，使我们能够研究二维费米极化子的平衡和远程平衡物理。该方法提供了对二极异性到全分子相变的无偏分析，而无需依赖粒子孔激发总数中的截断。我们的结果 - 包括基态能量和准粒子残基 - 与已知的蒙特卡洛计算符合定性一致。与常规数值方法相比，非高斯状态的主要优点是，它们使我们能够探索长时间的极性发展进化，尤其是研究固态和超速原子实验都可以访问的各种光谱特性。我们设计了两种类型的射频光谱，以测量偏振子和分子光谱功能。根据参数状态，我们发现杂质附近的这些光谱函数和费米密度曲线在排斥性和有吸引力的极性分支之间显示长寿命的振荡，或者表现出对分子状态的快速松弛动力学。
We develop a non-Gaussian variational approach that enables us to study both equilibrium and far-from-equilibrium physics of the two-dimensional Fermi polaron. This method provides an unbiased analysis of the polaron-to-molecule phase transition without relying on truncations in the total number of particle-hole excitations. Our results -- which include the ground state energy and quasiparticle residue -- are in qualitative agreement with the known Monte Carlo calculations. The main advantage of the non-Gaussian states compared to conventional numerical methods is that they enable us to explore long-time polaron evolution and, in particular, study various spectral properties accessible to both solid-state and ultracold atom experiments. We design two types of radiofrequency spectroscopies to measure polaronic and molecular spectral functions. Depending on the parameter regime, we find that these spectral functions and fermionic density profiles near the impurity display either long-lived oscillations between the repulsive and attractive polaron branches or exhibit fast relaxational dynamics to the molecular state.
