Beyond mean-field study of a binary bosonic mixture in a state-dependent honeycomb lattice

TL;DR

This study uses advanced numerical simulations to analyze a binary bosonic mixture in a honeycomb lattice, confirming mean-field theory's applicability and exploring correlation effects, but finds no evidence of the twisted superfluid pattern.

Contribution

It provides a detailed beyond-mean-field analysis of a binary bosonic mixture in a honeycomb lattice, clarifying the origin of the twisted superfluid state.

Findings

Mean-field theory is applicable within the experimental parameter range.

Correlation effects can cause asymmetries in measurements.

No evidence of twisted superfluid patterns was observed.

Abstract

We investigate a binary mixture of bosonic atoms loaded into a state-dependent honeycomb lattice. For this system, the emergence of a so-called twisted-superfluid ground state was experimentally observed in [Soltan-Panahi et al., Nat. Phys. 8, 71 (2012)]. Theoretically, the origin of this effect is not understood. We perform numerical simulations of an extended Bose-Hubbard model adapted to the experimental parameters employing the Multi-Layer Multi-Configuration Time-Dependent Hartree method for Bosons. Our results confirm the overall applicability of mean-field theory within the relevant parameter range. Beyond this, we provide a detailed analysis of correlation effects correcting the mean-field result. These have the potential to induce asymmetries in single shot time-of-flight measurements, but we find no indication of the patterns characteristic of the twisted superfluid. We comment on the restrictions of our model and possible extensions.