We study the properties of Bose polarons in two dimensions using quantum Monte Carlo techniques. Results for the binding energy, the effective mass, and the quasiparticle residue are reported for a typical strength of interactions in the gas and for a wide range of impurity-gas coupling strengths. A lower and an upper branch of the quasiparticle exist. The lower branch corresponds to an attractive polaron and spans from the regime of weak coupling where the impurity acts as a small density perturbation of the surrounding medium to deep bound states which involve many particles from the bath and extend as far as the healing length. The upper branch corresponds to an excited state where due to repulsion a low-density bubble forms around the impurity but might be unstable against decay into many-body bound states. Interaction effects strongly affect the quasiparticle properties of the polaron. In particular, in the strongly correlated regime, the impurity features a vanishing quasiparticle residue, signaling the transition from an almost free quasiparticle to a bound state involving many atoms from the bath.

中文翻译：

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二维气体中的强耦合玻色子极化子

我们使用量子蒙特卡洛技术研究二维玻色子极化子的性质。报告了结合能，有效质量和准粒子残基的结果，表明了气体中典型的相互作用强度以及各种杂质-气体偶联强度。存在准粒子的下部和上部分支。下分支对应于有吸引力的极化子，并跨越弱耦合机制，其中杂质充当周围介质的小密度扰动到深结合状态，深结合状态涉及浴液中的许多颗粒，并延伸至愈合长度。上分支对应于激发态，在该激发态中，由于排斥，在杂质周围形成低密度的气泡，但可能不稳定，无法衰变成多体结合态。相互作用效应强烈影响极化子的准粒子性质。特别地，在强相关机制中，杂质具有消失的准颗粒残基，表明从几乎自由的准颗粒过渡到包含许多来自镀液原子的结合态。