Role of interaction-induced tunneling in the dynamics of polar lattice bosons

Intersite dipolar interactions induce, even in absence of disorder, an intriguing nonergodic 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 intersite interactions. As a result, in stark contrast to the more studied case of hard-core bosons, delocalization is counterintuitively strengthened when the dipolar strength increases. Furthermore, the quasicancellation 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 nonergodic 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.

Automated summary

Intersite dipolar interactions induce nonergodic dynamics for dipolar bosons in an optical lattice, even without disorder. The neglected inherent dipole-induced density-dependent tunneling plays a crucial role in this dynamics. Delocalization is strengthened with increasing dipolar strength, in contrast to the case of hard-core bosons. Interaction-induced hopping should play a crucial role in future experiments on the dynamics of polar lattice gases.