Bulletin of the American Physical Society
2014 Annual Meeting of the Mid-Atlantic Section of the APS
Volume 59, Number 9
Friday–Sunday, October 3–5, 2014; University Park, Pennsylvania
Session C7: Atomic, Molecular and Optical Physics I |
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Chair: Donald Priour, Youngstown State University Room: Life Sciences Building 013 |
Saturday, October 4, 2014 10:30AM - 11:06AM |
C7.00001: Engineering Strongly Correlated States with Ultracold Atoms Invited Speaker: Vito Scarola Optical lattices containing ultracold alkali atoms represent nearly ideal manifestations of Hubbard models. As a result, they are being used to study poorly understood quantum states of matter. Some of the work in my group uses numerical modeling to help guide experiments in these searches. I will review our recent work that compares with ongoing optical lattice experiments trying to emulate the Fermi-Hubbard model in particular. The Fermi-Hubbard model is thought to capture some of the essential features of high temperature superconductors. I will discuss recent progress in using optical lattices to probe the controversial phase diagram of the Fermi-Hubbard model. I will also discuss a proposal to generalize current experimental setups beyond conventional Hubbard models to engineer exotic quantum states. We find that optical lattice experiments can use synthetics gauge fields to realize fractionalized collective excitations. [Preview Abstract] |
Saturday, October 4, 2014 11:06AM - 11:18AM |
C7.00002: Controlling the Interactions of Ultracold Atoms Using Anharmonic Optical Potentials Jessie Hirtenstein Ultracold atoms, when trapped by laser light, interact with each other differently according to the geometry of the potential well in which they are held. We are studying how the shape of a confining potential made of light affects the quantized energy levels of a pair of atoms. We have developed a numerical code that runs on American University's high-performance computing system and found the energies of two atoms by constructing and diagonalizing the Hamiltonian matrix. The simulations allow us to study how the energies change as a function of the trap shape and atom-atom coupling parameter. Our results should find application to laboratory experiments on ultracold atoms, bringing us a step closer to controlling the quantum world. [Preview Abstract] |
Saturday, October 4, 2014 11:18AM - 11:30AM |
C7.00003: Tuning and Locking a Diode Laser for a Magneto-Optical Trap Rachel Livingston, Matthew Gift, John Huckans, Ju Xin The purpose of a MOT is to utilize the atomic structure of rubidium-87 to manipulate a sample into an ultra-cold atom cloud in a vacuum sealed environment via a laser array. The extended cavity diode lasers used in this experiment must be tuned using an absorption spectroscopy system which utilizes the Doppler effect of light through a rubidium cell as the extended cavity of the diode laser is scanned across the rubidium absorption peaks with a piezo stack. The laser is then locked with a lock-in amplifier to ensure the frequency remains stable. When the lasers are locked they will be ready for use in the creation of a MOT. The light will be red-detuned so as to excite atoms moving towards each beam. When an atom absorbs the photon it will lose momentum along the photon's axis of motion, then spontaneously emit a photon of the observed frequency in a random direction. The isotropic nature of the emitted photons creates a randomly-directed recoil momentum in the affected atoms and reduces the average energy of the sample as a whole. With the orthogonal laser set-up and in conjunction with an anti-Helmholtz magnetic field this will create a point where the least energetic atoms will form an ultra-cold cloud with a temperature on the order of 200 microkelvins. [Preview Abstract] |
Saturday, October 4, 2014 11:30AM - 11:42AM |
C7.00004: Coherent individual addressing of neutral atom qubits in a 3D optical lattice Yang Wang, Xianli Zhang, Theodore A. Corcovilos, Aishwarya Kumar, David S. Weiss A collection of neutral atoms in a 3D optical lattice is a candidate quantum computer.We have recently demonstrated the ability to perform arbitrary single qubit rotations on target atoms in a 5x5x5 array, without affecting quantum information stored in other atoms. This is an important step in the demonstration of scalability in neutral atom quantum computers. [Preview Abstract] |
Saturday, October 4, 2014 11:42AM - 11:54AM |
C7.00005: Momentum-dependent 3-body loss in out-of-equilibrium 1D Bose gases Laura Zundel, Lin Xia, Jean-Felix Riou, David Weiss We measure the 3-body loss rates for out-of-equilibrium one-dimensional Bose gases of varying average energies and infer that the three body collision cross section depends strongly on the momentum distributions. We present a loss model based on momentum dependent correlations and show that it describes the data well. Calculating correlations in out-of-equilibrium many-body systems remains a theoretical challenge. These experiments provide insight into how these correlations evolve. [Preview Abstract] |
Saturday, October 4, 2014 11:54AM - 12:06PM |
C7.00006: Classical Study of Atomic Bound State Dynamics in Circularly Polarized Ultrastrong Fields Sui Luo, Patrick Grugan, Barry Walker We investigate hydrogen-like atoms in ultrastrong fields up to 1000 a.u. ($3\times10^{22}W/cm^{2}$). We find the influence of the magnetic component (B$\_$laser) of the external ultrastrong field introduces perturbations for the bound states of the atom. For intensities up to $1\times10^{19}W/cm^{2}$ the changes in the trajectory energies and Poincare plots are on the order of a few percent. While small, the changes from B$\_$laser with circular polarized (CP) light can result in a several fold decrease in the ionization probability at the highest intensities for the bound states, where ionization approaches 50$\%$. For these highest intensities, we find the Lorentz force from B$\_$laser exerts a force on the bound electron perpendicular to the rotating plane of the CP light. Since these trajectories are then aligned away from the minimum in the potential barrier it is stabilized against tunneling ionization. The results provide a classical understanding for ionization in ultrastrong fields and indicate relativistic effects in ultrastrong field ionization may most easily seen with CP field. [Preview Abstract] |
Saturday, October 4, 2014 12:06PM - 12:18PM |
C7.00007: Experimental Resolution of 100 keV to MeV Photoionization from Ultrahigh Intensity Ionization of Atoms Barry Walker, Patrick Grugan, Siyu Luo, Sui Luo Recent work on the ionization of atoms by ultrahigh intensities ($2\times10^{19} W/cm^{2}$) has shown that photoelectrons are strongly forward scattered and atomic shell structure plays a significant role in the energy resolved photoelectron spectrum and angular distribution [1]. The energy and angular resolutions for these previous experiments were $30\%$ and $4 ^{\circ}$, respectively. The experiments were unable to determine the yield of photoelectrons beyond 2 MeV or observe potential dynamics due to excitation from photoelectron rescattering with the parent ion in the ultrastrong field. We will discuss the recent results and a new magnetic spectrometer, currently under construction, that will allow for better angular and energy resolution of the 100 keV to MeV photoelectrons. Additional benefits of the new system include the ability to resolve photoelectrons above 4 MeV, an order of magnitude improvement in the signal to noise, and an increased sample density at the laser focus creating the ultrahigh intensity. \\[4pt] [1] N. Ekanayake, et al PRL 110, 203003 (2013) [Preview Abstract] |
Saturday, October 4, 2014 12:18PM - 12:30PM |
C7.00008: The linear stability of the principle relative equilibria in the Coulomb $(n+1)$ body problem Charles Jaffe, John E. Martin, III The linear stability of the principle relative equilibria of the Coulomb $(n+1)$-body problem is studied. The $n$ particles are the electrons having a charge of -1 and the $(n+1)^{th}$ particle is the nucleus having a positive charge $Z$ equal to the atomic number. The mass of the nucleus is over three orders of magnitude greater than that of the electrons. Treating the $n$ electrons as identical particles allows the introduction of symmetry variables. This block diagonalizes the Jacobian matrix and consequently factors the characteristic polynomial. [Preview Abstract] |
Saturday, October 4, 2014 12:30PM - 12:42PM |
C7.00009: Polarization Studies of Highly Oriented Carbon Dioxide Super Rotors Matthew J. Murray, Hannah M. Ogden, Carlos Toro, Qingnan Liu, Amy S. Mullin Controlling molecular motion could enable manipulation of energy flow between molecules.~ We have used a high power optical centrifuge IR spectrometer to investigate energy transfer between molecular super rotors with oriented angular momenta.~ The polarizable electron cloud of the molecules interacts with the electric field of linearly polarized light that angularly accelerates over the time of the optical pulse.~ This process drives molecules into high angular momentum states that are oriented with the optical field and have energies far from equilibrium.~ High resolution transient IR spectroscopy reveals the dynamics of collisional energy transfer for these super excited rotors.~ We make time-dependent measurements of individual rotational states of carbon dioxide ranging from J$=$0 to J$=$100.~ Polarization-dependent studies show that the initial angular momentum orientation persists even after thousands of collisions, indicating that molecules in an optical centrifuge behave as quantum gyroscopes. [Preview Abstract] |
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