Natalia Matveeva, Stefano Giorgini
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 the effective mass of this polaron exhibits a crossover from a free-moving to a tightly-bound regime where the impurity, apart from rare hopping events, remains localized within a length scale smaller than the lattice spacing.
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http://arxiv.org/abs/1306.5588
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