Interaction-Enhanced Group Velocity of Bosons in the Flat Band of an Optical Kagome Lattice

Geometric frustration of particle motion in a kagome lattice causes the single-particle band structure to have a flat s-orbital band. We probe this band structure by exciting a Bose-Einstein condensate into excited Bloch states of an optical kagome lattice, and then measuring the group velocity thro...

Full description

Saved in:
Bibliographic Details
Published inarXiv.org
Main Authors Leung, Tsz-Him, Schwarz, Malte N, Shao-Wen, Chang, Brown, Charles D, Unnikrishnan, Govind, Stamper-Kurn, Dan
Format Paper Journal Article
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 12.07.2020
Subjects
Band structure of solids
Band theory
Bose-Einstein condensates
Bosons
Group velocity
Kagome lattice
Particle motion
Physics - Atomic Physics
Physics - Quantum Gases
Online AccessGet full text

Cover

More Information
Summary:Geometric frustration of particle motion in a kagome lattice causes the single-particle band structure to have a flat s-orbital band. We probe this band structure by exciting a Bose-Einstein condensate into excited Bloch states of an optical kagome lattice, and then measuring the group velocity through the atomic momentum distribution. We find that interactions renormalize the band structure of the kagome lattice, greatly increasing the dispersion of the third band that, according to non-interacting band theory, should be nearly non-dispersing. Measurements at various lattice depths and gas densities agree quantitatively with predictions of the lattice Gross-Pitaevskii equation, indicating that the observed distortion of band structure is caused by the disortion of the overall lattice potential away from the kagome geometry by interactions.
ISSN:2331-8422
DOI:10.48550/arxiv.2007.05928