Bulletin of the American Physical Society
46th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 60, Number 7
Monday–Friday, June 8–12, 2015; Columbus, Ohio
Session T7: New Developments in Optical Lattices |
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Chair: Mukund Vengalatorre, Cornell University Room: Delaware CD |
Friday, June 12, 2015 8:00AM - 8:12AM |
T7.00001: Exploring the N\'{e}el phase using a compensated optical lattice Tsung-Lin Yang, Seth T. Coleman, Pedro M. Duarte, Russell A. Hart, Randall G. Hulet We have realized the Fermi-Hubbard model with fermionic $^{6}$Li atoms in a three-dimensional optical lattice. The red-detuned optical lattice is compensated by three additional blue-detuned laser beams which overlap each of the lattice beams, but are not retro-reflected. Using the compensated optical lattice, we have reached temperatures low enough to produce short-range antiferromagnetic (AF) spin correlations, which we detect via Bragg scattering of light. Previously, we reached temperatures down to 1.4 times that of the AFM phase transition,\footnote{R. A. Hart, P. M. Duarte et al., arXiv:1407.5932, to be published in Nature.} more than a factor of 2 below temperatures obtained previously in 3D optical lattices with fermions. However, the alignment stability of the lattice beams and the lack of tunability of the relative size of the lattice and compensating beam sizes hindered the optimization of the temperature. We have implemented an improved experimental setup which allows us to adjust the lattice beam waist ratios with better long-term stability. We will report on the status of these efforts and our progress on cooling deep into the N\'{e}el phase. [Preview Abstract] |
Friday, June 12, 2015 8:12AM - 8:24AM |
T7.00002: Fulde-Ferrell superfluids without spin-imbalance in three-dimensional driven spinful fermionic optical lattices Chunlei Qu, Zhen Zheng, Xubo Zou, Chuanwei Zhang Spin-imbalanced ultra-cold Fermi gases have been widely studied recently as a platform for exploring the long-sought Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluid phases, but so far conclusive evidence has not been found. Here we propose to realize an FF superfluid without spin imbalance in a three-dimensional (3D) fermionic cold atom optical lattice, where $s$- and $p$-orbital bands of the lattice are coupled by another weak moving optical lattice. Such coupling leads to a spin-independent asymmetric Fermi surface, which, together with the $s$-wave scattering interaction between two spins, yields an FF type of superfluid pairing. Unlike traditional schemes, our proposal does not rely on the spin imbalance (or an equivalent Zeeman field) to induce the Fermi surface mismatch and may provide a completely new route for realizing FF superfluids. [Preview Abstract] |
Friday, June 12, 2015 8:24AM - 8:36AM |
T7.00003: Coherent interaction of a Bose-Einstein condensate with two crossed cavity modes Julian Leonard, Andrea Morales, Philip Zupancic, Tobias Donner, Tilman Esslinger The realization of cavity-mediated long-range interactions in ultracold quantum gases leads to intriguing new many-body phenomena such as quantum phase transitions to self-ordered superradiant states. While such a state has been observed in a one-dimensional setup, extensions to higher dimensions that aim to exploit multimode configurations have only been suggested theoretically. Such systems are expected to exhibit rich phase diagrams with higher broken symmetries, frustration and glassy behavior. report on our latest results on coupling a Bose-Einstein condensate with two crossed cavity modes. The cavities cross under an angle of 60$^{\circ}$, which allows the study of self-ordered phases in different lattice shapes, such as hexagonal and triangular geometries. In addition to this tunable lattice geometry, our setup features a high-resolution imaging system, which will enable us to manipulate and probe the system locally. [Preview Abstract] |
Friday, June 12, 2015 8:36AM - 8:48AM |
T7.00004: Optical flux lattices using multi-frequency radiation Gediminas Juzeliunas, Tomas Andrijauskas, Ian Spielman Ultracold atomic gases are systems exhibiting various condensed matter phenomena. The ultracold atoms are neutral, so under usual circumstance they do not exhibit important magnetic phenomena, like the quantum Hall effect. Possible ways to create artificial magnetic field for ultracold atoms include rotation of an atomic cloud, laser-assisted tunnelling, shaking of optical lattices. Yet it is difficult to reach considerable magnetic fluxes required for achieving the fractional Hall effect. Here we theoretically analyse another way of creating a non-staggered magnetic flux for ultra-cold atoms by using a periodic sequence of short laser pulses providing a multi-frequency perturbation. In particular, we consider a possibility to create a square flux lattice for ultra-cold characterized by two internal states. The energies of the two internal states have opposite gradients in one spatial direction, while the driving consists of periodic in time pulses that couple the internal states and propagate in a direction perpendicular to the energy gradient. The time-depending perturbation effectively creates a square optical lattice affected by a non-staggered magnetic flux. The topological properties of such a lattice have been explored. [Preview Abstract] |
Friday, June 12, 2015 8:48AM - 9:00AM |
T7.00005: Fibonacci Optical Lattices Kevin Singh, Zachary Geiger, Ruwan Senaratne, Shankari Rajagopal, Kurt Fujiwara, David Weld Quasiperiodicity is intimately involved in quantum phenomena from localization to the quantum Hall effect. Recent experimental investigation of quasiperiodic quantum effects in photonic and electronic systems have revealed intriguing connections to topological phenomena. However, such experiments have been limited by the absence of techniques for creating tunable quasiperiodic structures. We propose a new type of quasiperiodic optical lattice, constructed by intersecting a Gaussian beam with a 2D square lattice at an angle with an irrational tangent. The resulting potential, a generalization of the Fibonacci lattice, is a physical realization of the mathematical ``cut-and-project'' construction which underlies all quasiperiodic structures. Calculation of the energies and wavefunctions of atoms loaded into the proposed quasiperiodic lattice demonstrate a fractal energy spectrum and the existence of edge states. [Preview Abstract] |
Friday, June 12, 2015 9:00AM - 9:12AM |
T7.00006: Raman sideband cooling of quantum degenerate $^{6}$Li Ahmed Omran, Martin Boll, Timon Hilker, Katharina Kleinlein, Guillaume Salomon, Immanuel Bloch, Christian Gross The ability of single-site resolved detection in optical lattice experiments had huge impact on the study of strongly correlated bosonic systems. In our experiment we plan to apply similar techniques to fermionic $^{6}$Li. However for strongly correlated fermions there does not yet exist an imaging technique which combines a sufficient ratio of signal to noise while keeping each atom trapped on its original lattice site. In this talk we present our approach, employing Raman sideband cooling. We discuss our progress using a far detuned optical lattice to pin the atomic distribution while performing Raman sideband cooling and simultaneously acquiring fluorescence light for single-atom imaging. We compare this to our results of a near resonant lattice, only 85 GHz detuned with respect to the $D_1$ transition of $^{6}$Li. [Preview Abstract] |
Friday, June 12, 2015 9:12AM - 9:24AM |
T7.00007: A Fermi Gas Microscope with Lithium-6 Maxwell Parsons, Sebastian Blatt, Christie Chiu, Florian Huber, Anton Mazurenko, Markus Greiner We demonstrate atom-resolved imaging of fermionic lithium-6 in an optical lattice. Lithium, with its fast dynamics and tunable interactions, is an ideal species for studying quantum many-body physics with ultracold atoms. However, lithium's large recoil energy and its unresolved excited state hyperfine structure make sub-Doppler laser cooling challenging. To solve this challenge, we have extended the technique of Raman sideband cooling to lithium in a very deep optical lattice. We load atoms into a single layer of a three-dimensional optical lattice with 566 nm lattice spacing, approximately 10 $\mu$m below a super-polished substrate that forms the last element of an imaging system with 0.85 numerical aperture. The lattice is then ramped to a depth of approximately 3 mK, where trap frequencies are on the order of 1 MHz. In this deep lattice we perform an alternating sequence of imaging and Raman sideband cooling pulses to image the atoms while keeping them pinned to their lattice sites. [Preview Abstract] |
Friday, June 12, 2015 9:24AM - 9:36AM |
T7.00008: A Quantum Gas Microscope for Ultracold Fermions Lawrence Cheuk, Matthew Nichols, Melih Okan, Thomas Lompe, Martin Zwierlein Ultracold atoms in optical lattices are ideal systems to study model quantum many-body physics in a clean and well-controlled environment. Experiments at Harvard and MPQ Munich using bosonic $^{87}$Rb atoms in optical lattices have demonstrated the ability to detect and address atoms at the single-site level, revealing microscopic density distributions and correlations difficult to extract from bulk measurements. The goal of our experiment is to achieve such single-site control for a quantum gas of fermions. This allows for exploring physics that arise in strongly-correlated fermionic systems. In this talk, we present results of site-resolved fluorescent imaging of fermionic $^{40}$K with high fidelity. [Preview Abstract] |
Friday, June 12, 2015 9:36AM - 9:48AM |
T7.00009: Optical Lattice Experiments with Lithium-7 Ivana Dimitrova, William Lunden, Niklas Jepsen, Jesse Amato-Grill, Yichao Yu, Wolfgang Ketterle The light mass of bosonic lithium makes it a potentially lucrative platform for exploring superexchange-driven physics in an optical lattice. The light mass of bosonic lithium makes it a potentially lucrative platform for exploring superexchange-driven physics in an optical lattice. We report on the observation of the superfluid-to-Mott insulator transition in our system and the restoration of coherence; the technical challenges related to the high recoil energy of lithium; and our first investigations using the system. [Preview Abstract] |
Friday, June 12, 2015 9:48AM - 10:00AM |
T7.00010: ABSTRACT WITHDRAWN |
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