Abstract
Mean-field Bloch bands of a Bose-Einstein condensate in a honeycomb optical lattice are computed. We find that the topological structure of the Bloch bands at the Dirac point is changed completely by atomic interaction of arbitrary small strength: the Dirac point is extended into a closed curve and an intersecting tube structure arises around the original Dirac point. These tubed Bloch bands are caused by the superfluidity of the system. Furthermore, they imply the inadequacy of the tight-binding model to describe an interacting Boson system around the Dirac point and the breakdown of adiabaticity by interaction of arbitrary small strength.
- Received 2 May 2011
DOI:https://doi.org/10.1103/PhysRevLett.107.065301
© 2011 American Physical Society
Synopsis
Dirac points multiply in the presence of a BEC
Published 1 August 2011
According to calculations, unexpected physics emerges when a Bose-Einstein condensate is confined to a hexagonal optical lattice.
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