Dynamically generated flat-band phases in optical kagome lattices

TL;DR

This paper explores the dynamic behavior of ultracold fermions in optical kagome lattices, revealing the formation of flat-band insulators, stripe phases, and oscillating topological currents, highlighting new possibilities for atomtronic applications.

Contribution

It introduces the concept of dynamically generated flat-band phases and topological states in optical kagome lattices, expanding understanding of nonequilibrium quantum transport in engineered lattice geometries.

Findings

Discovery of a dynamically generated flat-band insulator.

Observation of a dynamical stripe phase with weak repulsion.

Identification of oscillating topological chiral currents.

Abstract

Motivated by recent advances in the realization of complex two-dimensional optical lattices, we investigate theoretically the quantum transport of ultracold fermions in an optical kagome lattice. In particular, we focus on its extensively degenerate localized states (flat band). By loading fermions in a partial region of the lattice and depleting the mobile atoms at the far boundary of the initially unoccupied region, we find a dynamically generated flat-band insulator, which is also a population-inverted state. We further show that inclusion of weak repulsion leads to a dynamical stripe phase for two-component fermions in a similar setup. Finally, by preparing a topological insulating state in a partially occupied kagome lattice, we find that the topological chiral current decays but exhibits an interesting oscillating dynamics during the nonequilibrium transport. Given the broad variety of lattice geometries supporting localized or topological states, our work suggests new possibilities to use geometrical effects and their dynamics in atomtronic devices.