Quantum Geometry and Flat Band Bose-Einstein Condensation

Aleksi Julku, Georg M. Bruun, Päivi Törmä

Research output: Contribution to journalArticleScientificpeer-review

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We study the properties of a weakly interacting Bose-Einstein condensate (BEC) in a flat band lattice system by using the 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.

Original languageEnglish
Article number170404
Number of pages6
JournalPhysical Review Letters
Issue number17
Publication statusPublished - 22 Oct 2021
MoE publication typeA1 Journal article-refereed


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