Dipartimento di Fisica, Università di Trento and CNR-INO BEC Center, I-38050 Povo, Trento, Italy.
Phys Rev Lett. 2013 Nov 27;111(22):220405. doi: 10.1103/PhysRevLett.111.220405.
We consider a bilayer geometry where a single impurity moves in a two-dimensional plane and is coupled, via dipolar interactions, to a two-dimensional system of fermions residing in the second layer. Dipoles in both layers point in the same direction oriented by an external field perpendicular to the plane of motion. We use quantum Monte Carlo methods to calculate the binding energy and the effective mass of the impurity at zero temperature as a function of the distance between layers as well as of the in-plane interaction strength. In the regime where the fermionic dipoles form a Wigner crystal, the physics of the impurity can be described in terms of a polaron coupled to the bath of lattice phonons. By reducing the distance between layers this polaron exhibits a crossover from a free-moving to a tightly bound regime where its effective mass is orders of magnitude larger than the bare mass.
我们考虑一个双层几何结构，其中单个杂质在二维平面中移动，并通过偶极相互作用与位于第二层的二维费米子系统耦合。两层中的偶极子都指向由垂直于运动平面的外部磁场定向的相同方向。我们使用量子蒙特卡罗方法来计算在零温度下杂质的结合能和有效质量作为层间距离以及平面内相互作用强度的函数。在费米子偶极子形成维格纳晶体的区域，杂质的物理性质可以用与晶格声子浴耦合的极化子来描述。通过减小层间距离，这个极化子表现出从自由运动到紧密束缚的转变，其有效质量比裸质量大几个数量级。
