Vortex lattices of bosons in deep rotating lattices

Daniel S. Goldbaum

Daniel S. Goldbaum, Erich J. Mueller

We study vortex-lattice phases for a Bose gas trapped in a rotating optical-lattice near the superfluid--Mott-insulator transition. We find a series of abrupt structural phase transitions where vortices are pinned with their cores only on plaquettes or only on sites. We discuss connections between these vortex structures and the Hofstadter-butterfly spectrum of free particles on a rotating lattice.

Rajiv Bhat, Lincoln D. Carr, Murray Holland

Ahmed S. Hassan, Azza M. El-Badry, Alyaa A. Mahmoud +2 more

M. Centelles, M. Guilleumas, M. Barranco +2 more

Using mean field theory, we have studied Bose-Fermi mixtures in a one-dimensional optical lattice in the case of an attractive boson-fermion interaction. We consider that the fermions are in the degenerate regime and that the laser intensities are such that quantum coherence across the condensate is ensured. We discuss the effect of the optical lattice on the critical rotational frequency for vortex line creation in the Bose-Einstein condensate, as well as how it affects the stability of the boson-fermion mixture. A reduction of the critical frequency for nucleating a vortex is observed as the strength of the applied laser is increased. The onset of instability of the mixture occurs for a sizably lower number of fermions in the presence of a deep optical lattice.

Masahito Ueda, Hiroki Saito