Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 57, Number 11
Friday–Saturday, October 26–27, 2012; Socorro, New Mexico
Session B5: Atomic, Molecular, and Optical Physics |
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Chair: James Thompson, University of Colorado Boulder Room: Macey Center Silver |
Friday, October 26, 2012 10:40AM - 10:52AM |
B5.00001: Creating a Classical Model for Helium in a Strong Laser Field Ryan Sandberg, Grayson Tarbox, Justin Peatross, Michael Ware We present a computational model of the electrons in helium as they interact with an intense laser field. This work provides computational insight into an experiment measuring radiation from electrons with large wave packets. While this system is inherently quantum mechanical, many of its interesting features can be modeled using classical point charges. We present the model and show that it provides single and double ionization intensities for helium consistent with quantum mechanics. [Preview Abstract] |
Friday, October 26, 2012 10:52AM - 11:04AM |
B5.00002: Modeling Photoemission of Electrons in a High-Intensity Laser Focus Grayson Tarbox, Ryan Sandberg, Justin Peatross, Michael Ware We computationally model the interactions of electrons in a helium atom with an intense laser field. First quantized and second quantized theories differ in their predictions for how these electrons radiate while interacting with a strong laser field. It turns out that a classical model for electrons in helium captures many features found in the second quantized radiation theory. We use this type of classical model to study the expected volume wherein electrons are anticipated to achieve a significant red shift in their emission spectrum and also to explore radiation during the ionization process. We then determine the expected number of detectable photons to compare with the results of an ongoing experiment. [Preview Abstract] |
Friday, October 26, 2012 11:04AM - 11:16AM |
B5.00003: Radius of Laguerre Gaussian Beam Basil Davis The transverse structure of the Gouy phase shift in light beams carrying orbital angular momentum is analyzed. It is shown that the Gouy radius $r_G$ characterizing the transverse structure grows as $\sqrt{2p+|\ell|+1}$ with the nodal number $p$ and photon angular momentum number $\ell$. The Gouy radius is shown to be closely related to the root-mean-square radius of the beam, and the divergence of the radius away from the focal plane is determined. Finally, the rotation of the Poynting vector in the context of the Gouy radius is examined. [Preview Abstract] |
Friday, October 26, 2012 11:16AM - 11:28AM |
B5.00004: Ultracold Neutral Plasmas at Room Temperature Joshua Wilson, Stephen Rupper, Scott Bergeson, Nathan Heilmann Under certain conditions, the characteristics of ultracold neutral plasmas can be reproduced at room temperature. At high enough density the disorder-induced heating temperature is much greater than room temperature, meaning that the equilibrium ion temperature is determined by the ion density. We produce these plasmas using strong-field ionization of neon atoms in a jet. We have developed an interferometric method for determining the average plasma density as a function of time and observe the plasma expanding on time scales as short as 5 ns. We show that the ultracold neutral plasma expansion model can be used to extract the electron temperature with good reliability. [Preview Abstract] |
Friday, October 26, 2012 11:28AM - 11:40AM |
B5.00005: Quantum dynamics of molecular energy transfer using coupled operator algebras Tim Wendler, Gus Hart, Manuel Berrondo The Schrodinger equation for the time-evolution operator is sufficient for calculating quantum dynamics of the perturbed harmonic vibrational states of a single chemical bond. It is shown to be easily extended to more complex molecular energy transfers such as molecular collisions and chemical reactions through the coupling of algebras. This application of Lie algebra, called the vibron model, is shown to produce results in the following 3 examples: 1) Carbon dioxide absorbing energy from an external electromagnetic field, 2) Collinear inelastic collision of a diatomic molecule with in incoming atom, and 3) Collinear reactive collision of the deuterium with methane. [Preview Abstract] |
Friday, October 26, 2012 11:40AM - 11:52AM |
B5.00006: Determining Thin Film Roughness with Extreme Ultraviolet Light Cody Petrie, Stephen Harman, Steven Turley Understanding surface roughness is essential in ultraviolet (EUV) optics. The wavelength of EUV light is shorter than that of ultraviolet light, and as a result is more sensitive to surface roughness. At the shortest EUV wavelengths, the reflection and transmission are so sensitive to roughness that atomic force microscopy (AFM), and electron microscopy techniques are not sufficiently accurate to predict the effects roughness on the optical properties of thin-film mirrors. We have sputtered two single-layer uranium oxide films of thicknesses 44 $\pm$ 3nm and 408 $\pm$ 10nm to demonstrate an optical techniques for accurately determining surface properties of these films. We measured non-specular reflectance from these surfaces over several decades of intensity and compared these to calculations of scattering from rough surfaces. These measurements were consistent with AFM measurements of surface height, but had detail beyond what could be determined from AFM measurements alone. [Preview Abstract] |
Friday, October 26, 2012 11:52AM - 12:04PM |
B5.00007: Optical Constants of Uranium Oxide Thin Films, 1.25 to 6 eV Jordan Bell, David Allred The optical constants of uranium oxides are important for many applications including homeland security. Uranium forms many different oxides in many phases, making it difficult to study. In an effort to investigate optical properties of various uranium oxides, we used DC magnetron reactive sputtering (also utilizing a novel approach to improve thickness uniformity) to deposit three films, of approximate average thickness 44 nm, 114 nm, and 413 nm. We analyzed the films by multiangle spectroscopic ellipsometry, giving optical constants of roughly 1.8 to 2.2 for n, and 0 to 0.5 for k, over the range of 1.25 to 6.2 eV. The band gaps of the various materials are around 3.1 eV for direct band gaps, and 2 and 2.8 eV for indirect band gaps. [Preview Abstract] |
Friday, October 26, 2012 12:04PM - 12:16PM |
B5.00008: Enhanced Spin Squeezing Through Quantum Control of Qudits Leigh Norris, Collin Trail, Ivan Deutsch, Poul Jessen Spin squeezed states have applications in metrology and quantum information processing. Most spin squeezing research to date has focused on ensembles of qubit spins. We explore squeezed state production in an ensemble of spin f$>$1/2 alkali atoms (qudits). Collective interactions are achieved through coherent quantum feedback of a laser probe, interacting with the ensemble through Faraday interaction. This process is enhanced with control of the atomic qudits, both before and after the collective interaction. Initial preparation increases the collective squeezing parameter through enhancement of resolvable quantum fluctuations, but comes at the price of increased decoherence. We find an optimal state preparation, achieving an increased squeezing parameter while remaining robust to decoherence. After the collective interaction, qudit control maps generated entanglement to different pseudo-spin subspaces where it is metrologically useful, e.g., the clock transition or the stretched state for magnetometry. These considerations highlight the unique capabilities of our platform: we can transfer correlations between subspaces to explore a wider variety of nonclassical states, with ultimate application in sensors or quantum information processors. [Preview Abstract] |
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