Bulletin of the American Physical Society
47th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 61, Number 8
Monday–Friday, May 23–27, 2016; Providence, Rhode Island
Session A1: DAMOP Prize SessionFocus Undergraduate
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Chair: David Weiss, Pennsylvania State University Room: Ballroom A |
Tuesday, May 24, 2016 8:00AM - 8:05AM |
A1.00001: Opening Remarks Opening remarks for the the DAMOP16 Conference. [Preview Abstract] |
Tuesday, May 24, 2016 8:05AM - 8:35AM |
A1.00002: Davisson-Germer Prize Talk: Many-Body Physics with Atomic Fermions Invited Speaker: Randall Hulet Ultracold atomic gases confined to optical lattices have proven to be highly versatile and tunable systems for realizing novel quantum states of matter. We are using Fermi gases of $^6$Li atoms in our laboratory to explore several goals related to the strong correlations that arise in these systems. We have realized the Hubbard model, which has long been suspected of containing the essential ingredients of high temperature superconductivity. We measured the compressibility of the Mott insulating phase that occurs near half filling (1 atom/site), thus demonstrating the excitation gap of the Mott insulator. Progress in this field, however, has been hampered by an inability to cool to low enough temperatures to achieve the most ambitious goals. To address this problem, we have developed the compensated optical lattice method to enable evaporative cooling in the lattice. With this method, we have cooled the Mott insulator sufficiently far to observe short-range antiferromagnetic correlations using Bragg scattering of light. We are currently exploring new methods for entropy storage and redistribution to achieve even lower entropy in the antiferromagnetic phase. Motivated by the enhancement of quantum correlations in low dimensions, we are also exploring Fermi gases in quasi-one-dimension (1D). A deep 2D optical lattice produces an array of 1D tubes which can be weakly coupled by reducing the lattice depth, thus increasing the lattice hopping $t$ between them. We observe a crossover from 1D-like to 3D-like behavior in the phase separation of a spin-imbalanced Fermi gas with increasing $t$. While this crossover occurs at a value of $t$ that depends on interaction, we find that the crossover location is universally dependent upon the scaled hopping $t / \varepsilon_\mathrm{b}$, where $\varepsilon_\mathrm{b}$ is the pair binding energy. Finally, I will also report progress on measuring the speed of sound of the charge and spin modes in a 1D Fermi gas. [Preview Abstract] |
Tuesday, May 24, 2016 8:35AM - 9:05AM |
A1.00003: Will Allis Prize Talk: Electron Collisions -- Experiment, Theory and Applications Invited Speaker: Klaus Bartschat Electron collisions with atoms, ions, and molecules represent one of the very early topics of quantum mechanics. In spite of the field's maturity, a number of recent developments in detector technology (e.g., the "reaction microscope" or the "magnetic-angle changer") and the rapid increase in computational resources have resulted in significant progress in the measurement, understanding, and theoretical/computational description of few-body Coulomb problems. Close collaborations between experimentalists and theorists worldwide continue to produce high-quality benchmark data, which allow for thoroughly testing and further developing a variety of theoretical approaches. As a result, it has now become possible to reliably calculate the vast amount of atomic data needed for detailed modelling of the physics and chemistry of planetary atmospheres, the interpretation of astrophysical data, optimizing the energy transport in reactive plasmas, and many other topics -- including light-driven processes, in which electrons are produced by continuous or short-pulse ultra-intense electromagnetic radiation. In this talk, I will highlight some of the recent developments that have had a major impact on the field. This will be followed by showcasing examples, in which accurate electron collision data enabled applications in fields beyond traditional AMO physics. Finally, open problems and challenges for the future will be outlined. [Preview Abstract] |
Tuesday, May 24, 2016 9:05AM - 9:35AM |
A1.00004: Maria Goeppert Mayer Prize Talk: Superfluid Atom Circuits Invited Speaker: Gretchen Campbell We have performed a series of experiments with ring-shaped Bose-Einstein Condensates, with and without the addition of a “weak link” barrier. Weak connections between superconductors or superfluids can differ from classical links due to quantum coherence, which allows for flow without resistance. The properties of a weak link are characterized by a single function, the current-phase relationship. In recent experiments, we have developed a technique to directly measure the current-phase relationship of the weak link. The weak link is created using a laser beam that acts as a barrier across one side of the ring condensate. By rotating the barrier, we can control the current around the ring. When the weak link is rotated at at low rotation rates, we observe phase slips between well-defined, quantized current states, and have demonstrated that the system exhibits hysteresis. At higher rotation rates we have directly measured the onset of resistive flow across the weak link. Such measurements may open new avenues of research in quantum transport. More recently, we have studied the behavior of the ring BEC when the radius is expanded at supersonic rates. Because information can propagate only at the speed of sound, the supersonic expansion creates causally disconnected regions, whose phases evolve at different rates. Such experiments may allow us to study cosmic inflation at laboratory scales. [Preview Abstract] |
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