Tunable anisotropic superfluidity in an optical kagome superlattice

TL;DR

This paper investigates the phase diagram of the Bose-Hubbard model on a kagome lattice with a tunable superlattice structure, revealing anisotropic superfluid phases and their signatures in experiments.

Contribution

It introduces a detailed analysis of anisotropic superfluidity in a tunable kagome superlattice using Quantum Monte Carlo and Landau theory, highlighting novel phase behaviors.

Findings

Discovery of Mott phases with non-integer filling and stripe order

Identification of anisotropic superfluid phases with direction-dependent superfluid density

Observation of changing superfluid anisotropy with particle number and hopping strength

Abstract

We study the phase diagram of the Bose-Hubbard model on the kagome lattice with a broken sublattice symmetry. Such a superlattice structure can naturally be created and tuned by changing the potential offset of one sublattice in the optical generation of the frustrated lattice. The superstructure gives rise to a rich quantum phase diagram, which is analyzed by combining Quantum Monte Carlo simulations with the Generalized Effective Potential Landau Theory. Mott phases with non-integer filling and a characteristic order along stripes are found, which show a transition to a superfluid phase with an anisotropic superfluid density. Surprisingly, the direction of the superfluid anisotropy is changing between different symmetry directions as a function of the particle number or the hopping strength. Finally, we discuss characteristic signatures of anisotropic phases in time-of-flight absorption measurements.