Interaction Driven Interband Tunneling of Bosons in the Triple Well

TL;DR

This paper investigates how strongly interacting bosons in a triple-well potential can exhibit enhanced interband tunneling, revealing new tunneling phenomena beyond the single-band approximation through numerical analysis.

Contribution

It demonstrates the existence of interband tunneling windows in strongly repulsive bosons, incorporating higher band effects and providing a generalized basis for explanation.

Findings

Enhanced tunneling occurs in strong interaction regimes due to higher band contributions.

Interband tunneling enables single-boson and two-boson correlated tunneling processes.

Robustness of interband tunneling against potential deformations is confirmed.

Abstract

We study the tunneling of a small ensemble of strongly repulsive bosons in a one-dimensional triple-well potential. The usual treatment within the single-band approximation suggests suppression of tunneling in the strong interaction regime. However, we show that several windows of enhanced tunneling are opened in this regime. This enhanced tunneling results from higher band contributions, and has the character of interband tunneling. It can give rise to various tunneling processes, such as single-boson tunneling and two-boson correlated tunneling of the ensemble of bosons, and is robust against deformations of the triple well potential. We introduce a basis of generalized number states including all contributing bands to explain the interband tunneling, and demonstrate various processes of interband tunneling and its robustness by numerically exact calculation.