Bulletin of the American Physical Society
16th Annual Meeting of the Northwest Section of the APS
Volume 60, Number 6
Thursday–Saturday, May 14–16, 2015; Pullman, Washington
Session B8: Ultracold Atomic Gases and More |
Hide Abstracts |
Chair: Peter Engels, Washington State University Room: Smith Center for Undergraduate Education (CUE) 202 |
Friday, May 15, 2015 3:30PM - 4:00PM |
B8.00001: Spin diffusion and instabilities in a nondegenerate Bose gas Invited Speaker: Jeffrey McGuirk Coherence and quantum symmetries can lead to non-classical diffusion in ultra-cold gases. I will present results from studies of longitudinal spin diffusion of two pseudo-spin domains in a trapped $^{87}$Rb sample above quantum degeneracy, including investigations of the effect of coherence in the domain wall on the dynamics of the system. Coherence in the domain wall leads to transverse-spin-mediated longitudinal spin diffusion that is slower than classical predictions, as well as altering the domains' oscillation frequency. This spin system also shows an instability in the longitudinal spin dynamics as the longitudinal and transverse spin components couple, and a conversion of longitudinal spin to transverse spin is observed, resulting in an increase in the total amount of coherence in the system. [Preview Abstract] |
Friday, May 15, 2015 4:00PM - 4:12PM |
B8.00002: Roton minimum-like excitations in a Bose-Einstein condensate M.A. Khamehchi, M.E. Mossman, Peter Engels We report on experiments utilizing Bragg spectroscopy to probe the excitation spectrum of a spin-orbit coupled BEC. The spin-orbit coupling is induced by a Raman dressing scheme. The resulting dispersion relation features an interesting minimum at nonzero quasimomentum, reminiscent of the roton minimum known e.g. from superfluid helium systems. The current status of the experiment and our progress toward understanding the implications of this roton-like minimum will be discussed. [Preview Abstract] |
Friday, May 15, 2015 4:12PM - 4:24PM |
B8.00003: Engineering dispersion relations: Floquet-Bloch States in a Bose-Einstein Condensate Maren Mossman, M.A. Khamehchi, Peter Engels Bose-Einstein Condensates (BECs) provide a flexible platform to model a wide variety of condensed matter phenomena. To this goal, periodically driven optical lattices are a premier tool to create interesting band structures. By applying both static and moving lattices to a BEC, we investigate Floquet-Bloch states formed in these systems. In our scheme, the $s$ band and the $p_x$ band of a static lattice are coupled through a moving lattice, forming a hybrid $s$-$p_x$ band. The dispersion minimum is shifted away from zero quasimomentum, leading to an artificial gauge field for the atoms. We report our findings as well as future directions of these experiments. [Preview Abstract] |
Friday, May 15, 2015 4:24PM - 4:36PM |
B8.00004: Energy and structural properties of $N$-boson clusters with Efimov character Yangqian Yan, D. Blume The low-energy spectrum of $N$-boson clusters with pairwise zero-range interactions is believed to be governed by a three-body parameter. We study the ground state of $N$-boson clusters with infinite two-body scattering length by performing {\em{ab initio}} path-integral Monte Carlo simulations. To prevent Thomas collapse, we choose different three-body regulators. We first compare our results with the zero-range theory at the three-body level. The energy and structural properties of the models considered are in better agreement with the zero-range theory than those of two-body finite-range interaction models. We then calculate the energy of larger clusters and compare with predictions from the literature. Finally, we obtain structural properties and compare with those of two-body finite-range interaction models. [Preview Abstract] |
Friday, May 15, 2015 4:36PM - 4:48PM |
B8.00005: Trapped unitary two-component Fermi gases with up to ten particles X.Y. Yin, D. Blume The properties of two-component Fermi gases with zero-range interactions are universal. We use an explicitly correlated Gaussian basis set expansion approach to investigate small equal-mass two-component Fermi gases under spherically symmetric external harmonic confinement. At unitarity, we determine the ground state energy for systems with up to ten particles interacting through finite-range two-body potentials for both even and odd number of particles. We extrapolate the energies to the zero-range limit using a novel scheme that removes the linear and, in some cases, also the quadratic dependence of the ground state energies on the two-body range. Our extrapolated zero-range energies are compared with results from the literature. We also calculate structural properties and the two-body Tan contact. [Preview Abstract] |
Friday, May 15, 2015 4:48PM - 5:00PM |
B8.00006: Tunneling dynamics of two interacting one-dimensional particles Seyed Ebrahim Gharashi, D. Blume We present our results on simulation of the cold atom tunneling experiments by the Heidelberg group [G. Z\"urn {\em{et al.}}, Phys. Rev. Lett. {\bf{108}}, 075303 (2012), G. Z\"urn {\em{et al.}}, Phys. Rev. Lett. {\bf{111}}, 175302 (2013)] on one or two $^6$Li atoms confined by a potential that consists of an approximately harmonic optical trap plus a linear magnetic field gradient. At the single particle level, we find that the WKB approximation may not be used as a reliable tool to extract the trapping potential parameters from tunneling data. We use our numerical calculations along with the experimental single particle tunneling rates to reparametrize the trapping potential. For two interacting atoms on the upper branch, we reproduce the experimental results. For infinitely strong interaction strength, we compare the time dynamics with that of two identical fermions and discuss the implications of fermionization for the dynamics. For two attractively interacting atoms on the molecular branch, we find qualitative agreement with experimental results. Pair tunneling dominates for strongly attractive interactions while single-particle tunneling dominates for weak interactions. [Preview Abstract] |
Friday, May 15, 2015 5:00PM - 5:12PM |
B8.00007: It may be possible to Make Compact Gamma Ray Lasers Richard Kriske This author had previously advanced a theory that Capillary Action may have a Quantum Mechanical explanation that would allow it to be used for all sorts of exotic devices and to explain a great number of unknown phenomena. This author proposed that ``holes'' travel downward in a Capillary tube, and this semiconductor mechanism was actually responsible for the workings of Capillary tubes. It may be that Anti-electrons also can be made to travel down Capillary tubes, in that they are mathematically similar to ``holes.'' If this is the case, then perhaps molecules of Antimatter could also travel through Capillary tubes, and a powerful yet small Gamma Ray Laser could be constructed. In order to generate X-ray Lasers, there needs to be a large and cumbersome Particle Accelerator and Wigglers in the Case of the Free Electron Laser. The Gamma Ray Laser would be much smaller, but could use input of Anti-Electrons from a particle accelerator of Positronium. A Gamma Ray Laser would be the most easily used Laser for a probe of the Nucleus, and as a device for developing ``Laser Forced Nuclear Fission'' and Fusion devices. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700