Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 30: Matter At Low Temperature: Quantum Liquids, Bose-Einstein Condensates, Ultra-cold Atoms, ... 1
TT 30.6: Vortrag
Mittwoch, 28. März 2012, 16:30–16:45, H 3005
Spin-1 Bosons in Optical Superlattices — •Andreas Wagner1, Andreas Nunnenkamp1, Eugene Demler2, and Christoph Bruder1 — 1University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland — 2Harvard University, Cambridge, MA 02138, USA
We examine spinor Bose-Einstein condensates in optical period-2 superlattices theoretically using a Bose-Hubbard Hamiltonian which takes spin effects into account. The system shows quantum phase transitions between Mott-insulating and superfluid phases. In particular, we study the spin-dependent effects on the phase diagram.
Within the Mott phase the extended superlattice corresponds to an array of isolated double-well potentials. For these systems we study single-particle tunneling which occurs when one lattice site is ramped up relatively to a neighboring site [1]. Spin-dependent effects modify the
tunneling events in a qualitative and a quantitative way. Depending on the asymmetry of the double well different types of magnetic order occur, making the system of spin-1 bosons in an optical superlattice a model for mesoscopic magnetism. Homogeneous and inhomogeneous magnetic fields are applied and the effects of the linear and the quadratic
Zeeman shifts are examined.We also investigate the bipartite entanglement between the sites and construct states of maximal entanglement. The entanglement in our system is due to both orbital and spin degrees of freedom. We calculate the contribution of orbital and spin entanglement and show that the sum of these two terms gives a lower bound for the total entanglement.
A. Wagner, C. Bruder, and E. Demler, arXiv:1110.1968