The role of interaction-induced tunneling in the dynamics of polar lattice bosons

TL;DR

This paper investigates how interaction-induced tunneling influences the non-ergodic dynamics of dipolar bosons in optical lattices, revealing that it can enhance delocalization and cause a decoupling of ergodic and non-ergodic states.

Contribution

It highlights the significant role of dipole-induced density-dependent tunneling, often neglected, in the dynamics of polar lattice bosons, especially in shallow lattices.

Findings

Interaction-induced tunneling can overcome localization in shallow lattices.

Delocalization increases with dipolar strength, contrary to typical expectations.

Near certain dipole strengths, Hilbert space decouples into ergodic and non-ergodic sectors.

Abstract

Inter-site dipolar interactions induce, even in absence of disorder, an intriguing non-ergodic dynamics for dipolar bosons in an optical lattice. We show that the inherent dipole-induced density-dependent tunneling, typically neglected, plays a crucial role in this dynamics. For shallow-enough lattices, the delocalization stemming from the interaction-induced hopping overcomes the localization induced by inter-site interactions. As a result, in stark contrast to the more studied case of hard-core bosons, delocalization is counter-intuitively strengthen when the dipolar strength increases. Furthermore, the quasi-cancellation between bare and interaction-induced tunneling may lead, near a lattice-depth-dependent value of the dipole strength, to an exact decoupling of the Hilbert space between ergodic hard-core states and strongly non-ergodic soft-core ones. Our results show that interaction-induced hopping should play a crucial role in future experiments on the dynamics of polar lattice gases.