Bour Shahin, Lee Dean, Hammer H-W, Meißner Ulf-G
Helmholtz-Institut für Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universität Bonn, 53115 Bonn, Germany.
Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA.
Phys Rev Lett. 2015 Oct 30;115(18):185301. doi: 10.1103/PhysRevLett.115.185301. Epub 2015 Oct 27.
We investigate the attractive Fermi polaron problem in two dimensions using nonperturbative Monte Carlo simulations. We introduce a new Monte Carlo algorithm called the impurity lattice Monte Carlo method. This algorithm samples the path integral in a computationally efficient manner and has only small sign oscillations for systems with a single impurity. As a benchmark of the method, we calculate the universal polaron energy in three dimensions in the scale-invariant unitarity limit and find agreement with published results. We then present the first fully nonperturbative calculations of the polaron energy in two dimensions and density correlations between the impurity and majority particles in the limit of zero-range interactions. We find evidence for a smooth crossover transition from fermionic quasiparticle to molecular state as a function of the interaction strength.
我们使用非微扰蒙特卡罗模拟研究二维中的吸引费米极化子问题。我们引入了一种新的蒙特卡罗算法，称为杂质晶格蒙特卡罗方法。该算法以计算高效的方式对路径积分进行采样，并且对于具有单个杂质的系统只有很小的符号振荡。作为该方法的基准，我们在尺度不变的幺正极限下计算三维中的通用极化子能量，并发现与已发表的结果一致。然后，我们给出了二维中极化子能量以及在零程相互作用极限下杂质与多数粒子之间密度关联的首次完全非微扰计算。我们发现了作为相互作用强度函数，从费米子准粒子到分子态的平滑交叉转变的证据。
