Two-dimensional Bose polaron using diffusion Monte Carlo method

We investigate the properties of a mobile impurity immersed in a two-dimensional (2D) Bose gas at zero temperature using quantum Monte Carlo (QMC) methods. The repulsive boson-boson and impurity-boson interactions are modeled by hard-disk potentials with positive scattering lengths a and b, respectively, taken to be equal to the scattering lengths. We calculate the polaron energy and effective mass for the density parameter na(2) << 1 and the ratio a/b. We find that at low densities perturbation theory adequately describes the simulation results. As the impurity-boson interaction strength increases, the polaron mass is enhanced. Additionally, we calculate the structural properties of the Bose system, such as the impurity-boson pair-correlation function and the change of the density profile around the impurity.