Quantum geometry and flat band Bose-Einstein condensation
Abstract
We study the properties of a weakly interacting Bose-Einstein condensate (BEC) in a flat band lattice system by using multiband Bogoliubov theory, and discover fundamental connections to the underlying quantum geometry. In a flat band, the speed of sound and the quantum depletion of the condensate are dictated by the quantum geometry, and a finite quantum distance between the condensed and other states guarantees stability of the BEC. Our results reveal that a suitable quantum geometry allows one to reach the strong quantum correlation regime even with weak interactions.
Cite
@article{arxiv.2104.14257,
title = {Quantum geometry and flat band Bose-Einstein condensation},
author = {Aleksi Julku and Georg M. Bruun and Päivi Törmä},
journal= {arXiv preprint arXiv:2104.14257},
year = {2021}
}
Comments
This document includes a letter "Quantum geometry and flat band Bose-Einstein condensation" and a longer article "Excitations of a Bose-Einstein condensate and the quantum geometry of a flat band". The former presents the main, and the latter the details of the calculations, considers physical quantities not studied in the letter, and provides a substantially extended discussion of the subject