Superfluid Fraction of a 2D Bose-Einstein Condensate in a Triangular Lattice
Abstract
We experimentally investigate the superfluid properties of a two-dimensional, weakly interacting Bose-Einstein condensate in the zero-temperature regime, when it is subjected to a triangular optical lattice potential. We implement an original method, which involves solving the hydrodynamic continuity equation to extract the superfluid fraction tensor from the measured in situ density distribution of the fluid at rest. In parallel, we apply an independent dynamical approach that combines compressibility and sound velocity measurements to determine the superfluid fraction. Both methods yield consistent results in good agreement with simulations of the Gross-Pitaevskii equation as well as with the Leggett bounds determined from the measured density profiles.
Keywords
Cite
@article{arxiv.2511.04575,
title = {Superfluid Fraction of a 2D Bose-Einstein Condensate in a Triangular Lattice},
author = {F. Rabec and G. Brochier and S. Wattellier and G. Chauveau and Y. Li and S. Nascimbene and J. Dalibard and J. Beugnon},
journal= {arXiv preprint arXiv:2511.04575},
year = {2025}
}