Dresden 2011 – scientific programme

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A: Fachverband Atomphysik

A 17: Ultra-cold atoms, ions and BEC IV (with Q)

A 17.4: Talk

Wednesday, March 16, 2011, 17:15–17:30, BAR 205

Spinor Bose-Einstein condensates in optical superlattices — •Andreas Wagner and Christoph Bruder — University of Basel

We examine spinor Bose-Einstein condensates in optical superlattices theoretically using a Bose-Hubbard hamiltonian which takes spin effects into account. Assuming that a small number of spin-one bosons is loaded in an optical potential, we study single-particle tunneling which occurs when one lattice site is ramped up relative to a neighbouring site. Spin-dependent effects modify the tunneling events in a qualitative and a quantitative way. We use a double-well potential as a unit cell of a one-dimensional superlattice and a four-well square-shaped potential as a unit cell of a two-dimensional superlattice. Homogeneous and inhomogeneous magnetic fields lead to spin-flip transitions and various other effects. E.g. it is possible for the four-well potential to observe spin-ordered states and non-trivial tunneling events, i.e. events at which at one site the particle number increases although the potential energy increases simultaneously. Finally, we investigate the bipartite entanglement between single sites and the remainder of the system and construct states of maximal entanglement.