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 G5: Dipolar Quantum Gases |
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Chair: Jonathan Weinstein, University of Nevada, Reno Room: Garden 3 |
Wednesday, June 6, 2012 8:00AM - 8:12AM |
G5.00001: Towards Bose-Einstein condensation of Erbium atoms Kiyotaka Aikawa, Albert Frisch, Michael Mark, Alexander Rietzler, Johannes Schindler, Erik Zupanic, Simon Baier, Rudolf Grimm, Francesca Ferlaino Ultracold dipolar gases offer a promising playground for exploring a wide variety of novel quantum phases as well as quantum magnetism. Recent advances in laser cooling technique have opened up a possibility to reach ultracold temperature with highly magnetic rare-earth atoms. Here, we present our results towards Bose-Einstein condensation of Erbium atoms. By using a broad transition at 401 nm for Zeeman slowing and a narrow transition at 583 nm for a magneto-optical trap (MOT), we obtained up to $3\times 10^8$ atoms at a temperature of 15 $\mu $K. Typically $1\times 10^7$ atoms are directly loaded from a MOT into an optical dipole trap operating at 1064 nm. The results show that our approach gives a good starting condition for evaporative cooling. [Preview Abstract] |
Wednesday, June 6, 2012 8:12AM - 8:24AM |
G5.00002: Novel bond order phase of dipolar fermions Satyan Bhongale, Ludwig Mathey, Shan-Wen Tsai, Charles Clark, Erhai Zhao Cold atoms provide a promising platform to solve problems that, although computationally infeasible, are of immense importance to condensed matter physics and material science. Ultra-cold bosonic atoms have been quite successful in emulating the Bose-Hubbard model. Experiments are now underway towards mapping out the unknown phase diagram of the Fermi-Hubbard model. Recent experimental advances in cooling dipolar gases to quantum degeneracy provide an unprecedented opportunity to engineer Hubbard-like models with long range interactions. Here we show that two new and exotic types of order emerge generically in dipolar fermion systems: bond order solids of $p$- and $d$-wave symmetry. Similar, but manifestly different, phases of two-dimensional correlated electronic systems have previously only been hypothesized. Our results suggest that these phases can be constructed flexibly with dipolar fermions, using currently available experimental techniques, providing detectable experimental signatures. [Preview Abstract] |
Wednesday, June 6, 2012 8:24AM - 8:36AM |
G5.00003: Quantum degenerate Bose-Fermi mixture of chemically different atomic species with widely tunable interactions Jee Woo Park, Cheng-Hsun Wu, Ibon Santiago, Tobias Tiecke, Sebastian Will, Peyman Ahmadi, Martin Zwierlein We have created a quantum degenerate Bose-Fermi mixture of $^{23}$Na and $^{40}$K with widely tunable interactions via broad interspecies Feshbach resonances. Over thirty Feshbach resonances between $^{23}$Na and $^{40}$K were identified, including $p$-wave multiplet resonances. The large and negative triplet background scattering length between $^{23}$Na and $^{40}$K causes a sharp enhancement of the fermion density in the presence of a Bose condensate. As explained via the asymptotic bound-state model (ABM), this strong background scattering leads to wide Feshbach resonances observed at low magnetic fields. Our work opens up the prospect to create chemically stable, fermionic ground state molecules of $^{23}$Na--$^{40}$K where strong, long-range dipolar interactions would set the dominant energy scale. [Preview Abstract] |
Wednesday, June 6, 2012 8:36AM - 8:48AM |
G5.00004: Probing Quantum Magnetism with Polar Molecules via Interaction Induced Dephasing Salvatore R. Manmana, Kaden R.A. Hazzard, Ana Maria Rey We show that strongly correlated many body states of quantum magnetic models can be dynamically generated even under current experimental conditions [1] at low filling factors and at temperatures above quantum degeneracy. This opens the way to verify a recent theoretical prediction [2] that the molecules' rotational states can be used to directly emulate quantum spins with strong ($>1$kHz) ``spin-spin'' interactions. We do this by considering the dynamics of fully polarized initial states which are easily realized in current experiments. Our analytic and DMRG calculations show that the dynamic experiments can quantitatively verify and characterize the spin model (XXZ) description of the system. As an outlook we propose how to experimentally generate interesting entangled states with polar molecules.\\[4pt] [1] A. Chotia et al., arXiv:1110.4420\\[0pt] [2] A.V. Gorshkov et al., PRL 107, 115301 (2011); PRA 84, 033619 (2011). [Preview Abstract] |
Wednesday, June 6, 2012 8:48AM - 9:00AM |
G5.00005: Controlling molecular scattering in optical lattices and fields Goulven Qu\'em\'ener, John Bohn Experimental physicists accomplished striking progress in preparing ultracold polar molecules in a precise quantum state [1]. Soon enough, one can envision ``ideal'' experiments of molecular physics where all quantum states of molecules can be addressed and detected. In addition, ultracold polar molecules benefit from a vast tool set of controls. Molecular chemical reactions can be enhanced by electric fields [2] or can be suppressed by optical lattices [3]. If the molecules have a magnetic dipole moment, they can also be controlled by magnetic fields. Starting from these ideas, we want to investigate what would be a scattering event between two molecules in an optical lattice, and in the presence of an electric and magnetic field. We will choose, as a probe example, the OH molecule which has either an electric and magnetic dipole moment. We will compare the effect of these additional external controls on the differential cross section and ask if we can trace back some information on the inter-molecular potential. \\[4pt] [1] Ni et al.,Science 322,231(2008).\\[0pt] [2] Qu\'em\'ener et al., Phys. Rev. A 81, 022702 (2010); Ni et al., Nature 464, 1324 (2010).\\[0pt] [3] Qu\'em\'ener et al., Phys. Rev. A 81, 060701(R)(2010); Phys. Rev. A 83, 012705 (2011); de Miranda et al., Nature Physics 7, 502 (2011). [Preview Abstract] |
Wednesday, June 6, 2012 9:00AM - 9:12AM |
G5.00006: The Molecular Hubbard Hamiltonian: field regimes and molecular species M.L. Wall, E. Bekaroglu, L.D. Carr The Molecular Hubbard Hamiltonian (MHH) is a lattice many-body Hamiltonian describing the low energy physics of $^1\Sigma$ heteronuclear alkali dimers loaded into an optical lattice. We present an overview of the derivation of this Hamiltonian, focusing in particular on how its parameters may be tuned experimentally. We also present a thorough exposition of the scales of the problem down to 1Hz, which allows for truncation of long-ranged terms in the MHH to a consistent level of approximation. The most experimentally relevant species KRb, LiCs, and RbCs access very different regimes of the MHH, and so will have different many-body features. We exemplify this point with Matrix Product State (MPS) simulations of the MHH for these species in near-term experimental configurations. [Preview Abstract] |
Wednesday, June 6, 2012 9:12AM - 9:24AM |
G5.00007: Tunable Holstein model with cold polar molecules Felipe Herrera, Roman V. Krems We show that ultracold polar molecules trapped on an optical lattice can be used for quantum simulation of the Holstein polaron model. Rotational excitation of molecules on the lattice produces excitons that are coupled to lattice phonons due to long-range dipole - dipole interactions. We show that the properties of the excitons and the phonons as well as the exciton-phonon couplings can be controlled by applying a dc electric field and by varying the intensity of the trapping laser field. We discuss the application of polar molecules on an optical lattice for quantum simulation of non-Markovian open quantum systems. We also explore the possibilty of realizing a transition from the strongly coupled Holstein polaron limit to the polaron regime described by the Su-Schrieffer-Heeger model. Reference: F. Herrera and R. V. Krems, Phys. Rev. A 84, 051401(R) (2011) [Preview Abstract] |
Wednesday, June 6, 2012 9:24AM - 9:36AM |
G5.00008: Correlation functions of dipolar gases at zero and non-zero temperatures Christopher Ticknor, Andrew Sykes We study phase and density fluctuations in a quasi2D dipolar gas. We employ the Hartee-Fock-Bogoliubov (HFB) method to study finite temperature phase coherence. We use this method to study the Berezinskii-Kosterlitz-Thouless (BKT) transition. We contrast the results for dipolar-interactions to contact-interactions and compare our predictions against recent experiments. Additionally, we present analytic expressions for the correlation functions at zero temperature. We observe the formation of a roton in the excitation spectrum as one varies the ratio between 2D-confinement-width and correlation (healing) length. We study the effect of this roton on the few-body correlation functions in the system. [Preview Abstract] |
Wednesday, June 6, 2012 9:36AM - 9:48AM |
G5.00009: Ultracold collisions between optically trapped sodium and rubidium atoms Dajun Wang, Ting-Fai Lam, Xiaoke Li, Fudong Wang, Dezhi Xiong NaRb molecule is a nice candidate for studying quantum gases with dipolar interactions because of its large electric dipole moment (3.3 Debye) and stability against exchange chemical reactions. We have constructed an all optical setup for producing ultracold Na and Rb atoms to obtain collisional and molecular spectroscopy information necessary for producing ground-state NaRb molecules. After loading an optical dipole trap directly from the two-species magneto-optical traps, evaporative cooling is applied by lowering the dipole trap potential. Heteronuclear photoassociation is then performed in the optical dipole trap near the Na (3S) + Rb (5P) asymptote. Progress toward the observation of Feshbch resonances between Na and Rb atoms will also be discussed. We are supported by Hong Kong RGC CUHK 403111. [Preview Abstract] |
Wednesday, June 6, 2012 9:48AM - 10:00AM |
G5.00010: Controling Interactions of Ultracold Er Atoms with Feshbach Resonances Svetlana Kotochigova, Alexander Petrov Here we pursue ideas for using anisotropic dipole-dipole and dispersion interactions to control collisional properties of ultracold magnetic Erbium (Er) atoms by using Feshbach resonances (FR). This kind of control will allow for converting a weakly interaction gas of atoms to a strongly interacting gas that can exhibit novel collective many-body states. Alternatively, interactions can be turn off all together to create an ideal gas, for which thermodynamic properties are known analytically. Feshbach resonances can also be used to create a BEC and associate atoms into highly magnetic molecules. For fermionic magnetic atoms the BCS-BEC phase transition and universal behavior of infinitely-strong interacting atoms can be studied. Finally, Efimov physics for the complex non-alkali atoms can be explored. The most interesting collision experiment occurs when magnetic Er atoms are prepared in the energetically-lowest Zeeman state $j=6$ and projection $m=-6$ at nanokelvin temperatures, as Feshbach resonances can be observed. Resonances in magnetic atoms must rely on anisotropic couplings to bound state with non-zero partial wave $\ell$. This is in contrast to collisions of alkali-metal atoms. Anisotropic interactions are much weaker there and, in addition, the hyperfine interaction between the electron and nuclear spin gives sufficient complexity so that most FR are due to $s$-wave bound states. [Preview Abstract] |
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