# Interaction induced single impurity tunneling in a binary mixture of trapped ultracold bosons

## TL;DR

This paper studies how a single impurity boson tunnels in a trapped ultracold mixture, revealing interaction-induced tunneling effects and entanglement dynamics sensitive to interspecies interactions.

## Contribution

It demonstrates that impurity tunneling is highly dependent on interspecies interactions and uncovers the role of entanglement in the tunneling process.

## Key findings

- Single impurity tunnels to neighboring sites after interaction quench
- Tunneling is suppressed without Bose gas interactions
- Strong entanglement develops during tunneling process

## Abstract

We investigate the tunneling dynamics of an ultracold bosonic impurity species which interacts repulsively with a second, larger Bose gas. Both species are held in a finite-sized quasi-one-dimensional box potential. In addition, the impurity bosons experience a periodic potential generated by an optical lattice. We initially prepare our binary mixture in its ground state, such that the impurities and Bose gas are phase separated and the impurities localize pairwise in adjacent sites of the periodic potential, by tuning the interaction strengths and the lattice depth correspondingly. The dynamics is initiated by suddenly lowering the repulsive interspecies interaction strength, thereby entering a different regime in the crossover diagram. For specific post-quench interspecies interaction strengths we find that a single impurity tunnels first to the neighbouring empty site and depending on the quench strength can further tunnel to the next neighbouring site. Interestingly, this effect is highly sensitive to the presence of the Bose gas and does not occur when the Bose gas does not interact with the impurity species throughout the dynamics. Moreover, we find that the tunneling process is accompanied by strong entanglement between the Bose gas and the impurity species as well as correlations among the impurities.