Bulletin of the American Physical Society
42nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 56, Number 5
Monday–Friday, June 13–17, 2011; Atlanta, Georgia
Session B3: Novel Techniques with Cold Atoms |
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Chair: Gretchen Campbell, JQI and NIST Room: A703 |
Tuesday, June 14, 2011 10:30AM - 10:42AM |
B3.00001: Resonance Imaging and Coherent Transport of Atoms in an Optical Lattice Jae Hoon Lee, Enrique Montano, Poul Jessen We describe experimental progress towards a resonance imaging protocol for optical lattices, aimed at robust preparation, addressing and transport of atoms with sub-wavelength resolution. Our setup consists of a 3D optical lattice, and a superimposed long-period (30 to 80 lattice sites) 1D ``superlattice'' that creates a position dependent shift of the transition frequency between two spin states in the ground manifold. We show that isolated planes of atoms can be prepared by flipping resonant spins with a microwave pulse and removing the remaining non-resonant spins. A second microwave pulse in a translated superlattice subsequently allows us to probe these planes with a resolution of better than 400nm. We further show that composite pulse techniques can reduce the sensitivity of the preparation to small variations in the relative position and intensity of the lattices. Finally, we explore the use of microwave pulses to drive coherent motion between lattice sites. [Preview Abstract] |
Tuesday, June 14, 2011 10:42AM - 10:54AM |
B3.00002: Probing an ultracold atomic crystal with matter waves Bryce Gadway, Daniel Pertot, Jeremy Reeves, Dominik Schneble We explore the scattering of matter waves from ultracold atoms held in an optical lattice. By ``shining'' a one-dimensional Bose gas onto an atomic Mott insulator (target), we observe Bragg diffraction peaks that reveal the target's crystalline structure. We find a systematic dependence of the Bragg peak intensity on the degree of atom localization, and recover a transition to coherent momentum and energy exchange (``Newton's cradle'') in the limit of free target atoms. Neutral-atom diffraction can serve as a novel experimental technique for probing atomic many-body systems. [Preview Abstract] |
Tuesday, June 14, 2011 10:54AM - 11:06AM |
B3.00003: Momentum-resolved spectroscopy of ultracold fermions in optical lattices Christoph Becker, S\"oren G\"otze, Jannes Heinze, Jasper Krauser, Bastian Hundt, Nick Fl\"aschner, Dirk-S\"oren L\"uhmann, Klaus Sengstock The periodic dispersion of electrons in crystals gives rise to many important phenomena in solid-state physics. To characterize such systems a measurement of the energies and fillings is required for the lowest bands. Ultracold fermionic atoms in optical lattices show essentially the same physics, however, with much better control over the system parameters. This includes especially the arbitrary tuning between different lattice depths: From weak to strong lattices, conductive and insulating phases can be realized. We present a spectroscopy method which is sensitive to both, form and filling of the different bands fully momentum-resolved. Thus, we can measure the full band structure and therefore extract very accurately all derived properties as e.g. the tunneling energy. Our sensitivity is promising for the extension of these studies to observe interaction shifts due to additional bosonic atoms as well as changes in the density of states for interacting fermionic gases. [Preview Abstract] |
Tuesday, June 14, 2011 11:06AM - 11:18AM |
B3.00004: Photon-assisted tunneling in an optical superlattice Sylvain Nascimbene, Monika Aidelsburger, Marcos Atala, Yu-Ao Chen, Stefan Trotzky, Immanuel Bloch We will present recent experimental results on photon-assisted tunneling of ultracold atoms in double-well potentials created by an optical superlattice. By shaking periodically the trapping potential, single atoms are transferred from one lattice site to another when the driving frequency matches the energy difference between wells. In the case of two atoms per double well, resonance conditions are modified by interactions and lead to the appearance of new features such as fractional photon resonances. We will also present the extension of this study to 1D gases, namely the study of ac-driven tunneling between neighbouring tubes, which is closely related to the observation of Shapiro steps in ac-driven Josephson junctions. Finally we will show that this technique can be used as a powerful probe of the spectral function of 1D gases, with the advantage of the absence of interaction effects in the final state. [Preview Abstract] |
Tuesday, June 14, 2011 11:18AM - 11:30AM |
B3.00005: Synthetic single beam heterodyne interferometry (SSHI) for continuous, high bandwidth, minimally destructive detection of ultracold atoms Mary Locke, Chad Fertig We demonstrate a new method, ``synthetic single beam heterodyne interferometry'' (SSHI), to continuously monitor rapid population dynamics in ultracold atomic clouds at the minimum destruction limit (i.e., with signal-to-noise determined solely by the maximum allowable spontaneous scattering rate and the measurement bandwidth). Similar to frequency modulation spectroscopy (FMS), SSHI encodes atom dynamics into the time-dependent shift of the optical phase of one spectral component relative to a second in a single laser beam. Unlike FMS, SSHI does not suffer from residual amplitude modulation (RAM) noise, is highly insensitive to intensity fluctuations, and does not require modulation frequencies of 100's of GHz to reach the minimum destruction regime. In SSHI, a large signal size is made compatible with low spontaneous scattering by passing only a weak laser through the atoms, subsequently interfering it with a bright beam that does not pass through the atoms. Unlike a true separated beams interferometer, however, SSHI is completely insensitive to mirror shake anywhere on any beam path. Details of the theory and measured performance of our scheme will be presented. [Preview Abstract] |
Tuesday, June 14, 2011 11:30AM - 11:42AM |
B3.00006: Discrete interferometer with individual trapped atoms Andreas Steffen, Andrea Alberti, Wolfgang Alt, Noomen Belmechri, Sebastian Hild, Michal Karski, Artur Widera, Dieter Meschede Coherent control and delocalization of individual atoms is a pivotal challenge in quantum technologies. As a new step on this road, we present an individual atom interferometer that is capable of splitting a trapped Cs atom by up to 10 $\mathrm{\mu m}$, allowing us to measure potential gradients on the microscale. The atom is confined in a 1D optical lattice, which is capable of performing discrete state-dependent shifts to split the atom by the desired number of sites. We establish a high degree of control, as the initial atom position, vibrational state and spin state can all be prepared with above 95\% fidelity. To unravel decoherence effects and phase influences, we have explored several basic interferometer geometries, among other things demonstrating a positional spin echo to cancel background effects. As a test case, an inertial force has been applied and successfully measured using the atomic phase. This will offer us a new tool to investigate the interaction between two atoms in a controlled model system. [Preview Abstract] |
Tuesday, June 14, 2011 11:42AM - 11:54AM |
B3.00007: Investigating the Effect of Density Inhomogenity on Photoemission Spectroscopy Tara Drake, John Gaebler, Rabin Paudel, J. Stewart, Deborah Jin Ultracold atomic gases realize clean and controllable model systems for investigating many-body quantum physics. However, trapped gases are intrinsically spatially inhomogeneous in their density, and in many cases, one would like to compare measurements of these systems with theoretical understanding for a homogeneous gas. In particular, density inhomogeneity can complicate the interpretation of data taken in momentum space, as the original spatial information is lost during time of flight expansion. The effect of density inhomogeneity due to a harmonic trapping potential is studied in a degenerate gas of 40K atoms. Using a method to select only the atoms in the center of the trap, we study how a more homogenous sample changes what can be seen in time of flight experiments, including photoemission spectroscopy. [Preview Abstract] |
Tuesday, June 14, 2011 11:54AM - 12:06PM |
B3.00008: Enabling Nanotechnology with Focused Ion Beams from Laser Cooled Atoms A.V. Steele, B. Knuffman, J. Orloff, M. Maazouz, J.J. McClelland The Magneto-Optical Trap Ion Source (MOTIS) being developed at NIST has the potential to enable numerous advances in nanoscale science. In a MOTIS, atoms are captured into a MOT, photoionized, and accelerated to an energy of a few hundred eV to a few tens of kV. A beam formed in this way can be brought to a tight focus, competitive with the commercial focused ion beam machines deployed widely today. Additionally, the unique characteristics of this source, coupled with the user's choice of ion from the long and growing list of laser-coolable atomic species suggest that the MOTIS has the potential to advance the state of the art in applications such as imaging, nanofabrication, secondary ion mass spectrometry, and others. I will present high-resolution images from our lithium and chromium MOTIS-based focused ion beams and discuss applications which we will pursue with these new tools. [Preview Abstract] |
Tuesday, June 14, 2011 12:06PM - 12:18PM |
B3.00009: Sub-wavelength optical trapping and manipulation using far-field optics Jeff Thompson, Tobias Tiecke, Alexey Gorshkov, Liang Jiang, Mikhail Lukin Coherent optical fields provide a powerful tool for trapping and manipulating quantum systems like atoms, ions and electron and nuclear spins in solid state systems. Diffraction sets a fundamental limit on the size of a beam focus, which appears to prohibit optical trapping or high-fidelity addressing of individual, identical atoms separated by a distance of order $\lambda$ or less. In this poster, we will present several methods for trapping and manipulating atoms with sub-wavelength spatial resolution. In principle, these techniques allow spatial resolutions approaching a few nanometers, using only far-field optics. Sub-wavelength optical dipole traps have several potential applications. The high curvature of the nonlinear traps may help to trap atoms near surfaces, e.g., in the evanescent field of an optical waveguide or micro-cavity. Also, pairs or clusters of atoms may be trapped near each other to execute high-fidelity fast quantum logic gates or mesoscopic quantum simulation. [Preview Abstract] |
Tuesday, June 14, 2011 12:18PM - 12:30PM |
B3.00010: Field Ionization of Cold Atoms near the Wall of a Single Carbon Nanotube Anne Goodsell, Trygve Ristroph, J.A. Golovchenko, Lene Vestergaard Hau We observe the capture and ?eld-ionization of individual atoms near the side wall of a single charged suspended nanotube. Our studies are carried out with a pulsed source of laser-cooled rubidium atoms. The interactions of cold atoms with nanostructures reveal extraordinary behaviors. Extremely large cross sections for ionization from the atomic beam are observed due to the nanotube's small radius, extended length, and the peculiar dynamics of a polarizable neutral atom near an extended, almost infinitely thin, charged wire. We observe the dynamics of both the capture and ionization process for individual atoms interacting with a single charged nanotube. The effects of the field strength on both processes are clearly distinguished in the data, as are prompt and delayed ionizations related to the locations at which they occur. The system can be used directly as a chip-integrated neutral atom detector with single atom sensitivity, high temporal and spatial resolution, and species selectivity. [Preview Abstract] |
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