Bulletin of the American Physical Society
43rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 57, Number 5
Monday–Friday, June 4–8, 2012; Orange County, California
Session P2: Synthetic Gauge Fields and Optical Lattices |
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Chair: Congjun Wu, University of California, San Diego Room: Grand Ballroom GF |
Thursday, June 7, 2012 2:00PM - 2:12PM |
P2.00001: Experimental Realization of Strong Effective Magnetic Fields in an Optical Lattice Yu-Ao Chen, Monika Aidelsburger, Marcos Atala, Sylvain Nascimbene, Stefan Trotzky, Immanuel Bloch Ultracold atoms in an optical lattice are promising candidates to study quantum many-body phenomena, such as the integer or fractional quantum Hall effect. Here we report about the experimental realization of strong effective magnetic fields with ultracold atoms using Raman assisted tunneling in an optical superlattice. We studied the nature of the frustrated ground state in the presence of an effective staggered magnetic field from its momentum distribution and directly revealed the quantum cyclotron orbit of a single atom exposed to the magnetic field. [Preview Abstract] |
Thursday, June 7, 2012 2:12PM - 2:24PM |
P2.00002: BEC in Spin-orbit Coupled Optical Lattices: Flat Band and Instability Chuanwei Zhang, Yongping Zhang We investigate the dynamics of a Bose-Einstein condensate (BEC) in the presence of spin-orbit coupling and a one dimensional optical lattice. We show that the combination of the experimentally already realized spin-orbit coupling and the optical lattice potential yields a flat ground state Bloch energy band. The dynamical and Landau instabilities of the BEC in the spin-orbit coupled optical lattice are also investigated. [Preview Abstract] |
Thursday, June 7, 2012 2:24PM - 2:36PM |
P2.00003: Phase-Sensitive Detection for Unconventional Bose-Einstein Condensations Zi Cai, Luming Duan, Congjun Wu We propose a phase-sensitive detection scheme to identify the unconventional $p_{x}\pm ip_{y}$ symmetry of the condensate wavefunctions of bosons, which have already been proposed and realized in high bands in optical lattices. Using the impulsive Raman operation combining with time-of-flight imaging, the off-diagonal correlation functions in momentum space give rise to the relative phase information between different components of condensate wavefunctions. This scheme is robust against the interaction and interband effects, and provides smoking gun evidence for unconventional Bose-Einstein condensations with nontrivial condensation symmetries. [Preview Abstract] |
Thursday, June 7, 2012 2:36PM - 2:48PM |
P2.00004: Topological phase transition in an $sp$- orbital chain Xiaopeng Li, Erhai Zhao, W. Vincent Liu We study an $sp$- orbital chain. The existence of edge states is discovered for this system. The quantum phases of the chain filled with fermions (half filling) are studied with exact diagonalization. We find a topological phase of fermions with edge states occupied. The topological phase is robust against small interactions. With sufficiently strong interaction the fermion system undergoes a topological phase transition to a inter-chain paired phase. [Preview Abstract] |
Thursday, June 7, 2012 2:48PM - 3:00PM |
P2.00005: The Peierls substitution in an engineered lattice potential Karina Jimenez-Garcia, Lindsay LeBlanc, Ross Williams, Matthew Beeler, Abigail Perry, Ian Spielman Artificial gauge fields open new possibilities to realize quantum many-body systems with ultracold atoms, by constructing Hamiltonians usually associated with electronic systems. In the presence of a periodic potential, artificial gauge fields may bring ultracold atoms closer to the quantum Hall regime. Here, we present a one-dimensional lattice derived purely from effective Zeeman-shifts generated by a combination of Raman coupling and radiofrequency magnetic fields. In this lattice the tunneling matrix element is generally complex. We control both the amplitude and the phase of this tunneling parameter, experimentally realizing the Peierls substitution for ultracold neutral atoms. [Preview Abstract] |
Thursday, June 7, 2012 3:00PM - 3:12PM |
P2.00006: Gauge Field Induced Momentum Transport in an Optical Lattice Patrick Windpassinger, Julian Struck, Malte Weinberg, Christoph Oelschlaeger, Juliette Simonet, Klaus Sengstock We present the experimental realization of a widely tuneable artificial gauge field for ultracold atoms in a one-dimensional optical lattice. We can simulate any Peierls phase ranging from zero to $2\pi$ in the tunneling matrix elements between nearest neighbours by applying an external periodic force to the atoms which is time-irreversible. This way it is possible to prepare ground state superfluids as well as out-of-equilibrium states at arbitrary, finite quasi momentum. We investigate the different time scales for adiabatic transport and relaxations mechanisms in the momentum space of the lattice. Extending these ideas to two-dimensional non-rectangular optical lattices it is possible to realize staggered magnetic field configurations with very large fluxes per plaquette. These results present a new step towards the emulation of strong field physics in optical lattices which may result in the realization of exotic phases like quantum hall states and other topological ordered phases with ultracold atoms. [Preview Abstract] |
Thursday, June 7, 2012 3:12PM - 3:24PM |
P2.00007: Bose Hubbard Model in a Synthetic Magnetic Field: Novel Chiral Mott Insulator State Arun Paramekanti, Maheswar Maji, Arya Dhar, Tapan Mishra, Ramesh Pai, Subroto Mukerjee Motivated by recent developments in realizing synthetic gauge fields for ultracold atoms, we study the Bose Hubbard model in the presence of half a magnetic flux quantum per lattice plaquette. We show, using density matrix renormalization group calculations and Monte Carlo simulations, that this ``fully frustrated'' Bose Hubbard model supports a novel Chiral Mott insulator phase with staggered loop currents for intermediate Hubbard repulsion on a two-leg ladder. This Chiral Mott insulator is flanked by a superfluid with staggered currents at weak repulsion, and an ordinary Mott insulator at strong repulsion. We discuss physical pictures for the Chiral Mott insulator as a vortex supersolid or an exciton condensate, and present a variational wavefunction which captures its essential correlations. We discuss observables, such as the gap, the momentum distribution, and loop current order across the phase diagram and propose interference measurements to detect the Chiral Mott state. [Preview Abstract] |
Thursday, June 7, 2012 3:24PM - 3:36PM |
P2.00008: Towards the observation of a Dicke type phase transition in spin-orbit coupled BECs Peter Engels, Chris Hamner, JiaJia Chang Spin-orbit coupling plays a major role in many condensed matter systems. Utilizing Raman coupling between two hyperfine states it is possible to add spin-orbit coupling to atomic systems as well. This is an important step toward investigating condensed matter physics with ultra cold atoms. Motivated by recent theoretical results we experimentally investigate a Dicke-model type phase transition in spin-orbit coupled $^{87}$Rb BECs. We report on recent and ongoing work. [Preview Abstract] |
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