Two-Dimensional Dynamics of Ultracold Atoms in Optical Lattices

TL;DR

This paper investigates the dynamics of ultracold bosonic atoms in two-dimensional optical lattices with different geometries, revealing how interactions and lattice topology influence transport and relaxation behaviors.

Contribution

It provides a comparative analysis of atom dynamics on square and hexagonal lattices under strong interactions, highlighting topology-dependent relaxation phenomena.

Findings

Square lattice shows insulating behavior with weak interactions.

Strong interactions cause slow relaxation on square lattice.

Hexagonal lattice exhibits relaxation to equilibrium regardless of interaction strength.

Abstract

We analyze the dynamics of ultracold atoms in optical lattices induced by a sudden shift of the underlying harmonic trapping potential. In order to study the effect of strong interactions, dimensionality and lattice topology on transport properties, we consider bosonic atoms with arbitrarily strong repulsive interactions, on a two-dimensional square lattice and a hexagonal lattice. On the square lattice we find insulating behavior for weakly interacting atoms and slow relaxation for strong interactions, even when a Mott plateau is present, which in one dimension blocks the dynamics. On the hexagonal lattice the center of mass relaxes to the new equilibrium for any interaction strength.