Localization of an impurity particle on a boson Mott insulator background

TL;DR

This paper studies how an impurity particle localizes in a three-dimensional bosonic Mott insulator lattice, identifying the critical interaction strength for polaron formation and exploring effects of lattice anisotropy and fluctuations.

Contribution

It provides exact results for impurity localization thresholds in a Mott insulator and analyzes the influence of lattice anisotropy, higher bands, and fluctuations.

Findings

Exact localization threshold in perfect Mott insulator

Effects of anisotropy and fluctuations on localization

Experimental feasibility via RF spectroscopy

Abstract

We investigate the behavior of a single particle hopping on a three dimensional cubic optical lattice in the presence of a Mott insulator of bosons in the same lattice. We calculate the critical interaction strength between the impurity and background bosons, beyond which there is bound state (polaron) formation. We give exact results in the limit of a perfect Mott insulator, where polaron formation is equivalent to impurity localization. We calculate the effects of lattice anisotropy, higher impurity bands, and fluctuations of the Mott insulator on the localization threshold. We argue that our results can be checked experimentally by RF spectroscopy of impurity particles.