Bulletin of the American Physical Society
43rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 57, Number 5
Monday–Friday, June 4–8, 2012; Orange County, California
Session U5: Matter-Wave Interferometry II and Cold Plasmas |
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Chair: Scott Bergeson, Brigham Young University Room: Garden 3 |
Friday, June 8, 2012 10:30AM - 10:42AM |
U5.00001: Using a lens for matter waves in an atom interferometer Raisa Trubko, Ivan Hromada, William Holmgren, Alexander Cronin We demonstrate the use of a lens for matter waves that increased our interference fringe contrast from 16{\%} to 24{\%}. To create our lens, we used a static electric field gradient inside our three nanograting Mach-Zehnder atom interferometer. We discovered that our lens (f = -500m) can compensate for misalignments, such as imperfect grating period. We explore how the (de)focusing effect can influence our precision measurements of atomic polarizability, and how such a lens can be useful in other layouts such as a Talbot Lau interferometer. We gratefully acknowledge NSF support for this work. [Preview Abstract] |
Friday, June 8, 2012 10:42AM - 10:54AM |
U5.00002: ABSTRACT HAS BEEN MOVED TO P7.00010 |
Friday, June 8, 2012 10:54AM - 11:06AM |
U5.00003: Electric and Magnetic Field Sensing with a Charged Particle Moire Deflectometer Roger Bach, Herman Batelaan, Glen Gronniger We report on the realization of a charged particle Moir\'{e} deflectometer and it ability to sense electric and magnetic fields. To the best of our knowledge this is the first realization of such a device. Our Moir\'{e} deflectometer is based on the classical propagation of an electron beam through a set of three identical nanofabricated gratings. This device can be used with or without collimation of the electron beam. Fields between the gratings shift the beam, resulting in a change in the total transmitted intensity. The scalability and sensitivity will be discussed as well as some of the complications. [Preview Abstract] |
Friday, June 8, 2012 11:06AM - 11:18AM |
U5.00004: An ionizing time domain matter-wave interferometer Nadine Doerre, Philipp Haslinger, Philipp Geyer, Jonas Rodewald, Stefan Nimmrichter, Klaus Hornberger, Markus Arndt We discuss an optical matter-wave interferometer for clusters and complex molecules that uses absorptive ionization gratings in combination with Talbot-Lau interferometry in the time domain. We show recent results and present the future perspectives of the experiment. In this setup, a particle cloud passes alongside a mirror that reflects three equally timed UV lasers pulses. Electrons are detached from the particles in the antinodes of the formed standing wave gratings via single photon absorption. The created ions are extracted and only neutral particles remain in the interferometer, thus absorptive light gratings for matter waves can be realized. In contrast to material grating setups, this experiment operates in a pulsed mode, which makes the longitudinal motion of the particles negligible. This new kind of interferometer is a universal tool which will on the one hand allow us to explore the wave nature of massive particles, potentially up to a million atomic mass units and more. In combination with deflectometry and spectroscopy on the other hand, it offers the possibility to determine molecular properties, such as polarizabilities, electric and magnetic moments, absorption and ionization cross sections with high precision. [Preview Abstract] |
Friday, June 8, 2012 11:18AM - 11:30AM |
U5.00005: Progress Toward a Cold Ion Interferometer James Archibald, Erickson Christopher, Jarom Jackson, Dallin Durfee We describe progress on a cold ion matter-wave interferometer. The ions are generated by laser-cooling strontium and then photo-ionizing the atoms with a two-photon transition to an auto- ionizing state in the continuum. Each ion's quantum wave will be split and recombined using stimulated Raman transitions between the hyperfine ground states of Sr$^{87+}$. The interferometer phase will be determined by measuring the fraction of ions exiting in each hyperfine state. We will discuss the theory of operation, experimental methods, and potential applications of the device. [Preview Abstract] |
Friday, June 8, 2012 11:30AM - 11:42AM |
U5.00006: Minimizing the effects of disorder-induced heating through electron screening in ultracold plasmas Mary Lyon, Scott Bergeson Strong coupling in plasmas is characterized by the ratio of the nearest-neighbor Coulomb potential energy to the average kinetic energy of the ions. In ultracold plasmas, which are produced by photoionizing laser-cooled atoms, the initial strong coupling parameter is large, due to the low initial temperature of the system. The value of the strong coupling parameter at equilibrium is limited by the relaxation of the ions due to nearest-neighbor interactions, which is called disorder-induced heating (DIH). The effects of DIH can be moderated through electron shielding. Electron screening extends the DIH time and reduces the ion equilibration temperature, thus decreasing the overall effect of DIH on the ion motion. However electron screening also softens the ion-ion interaction strength. The net result is a decrease in the strong coupling of the plasma. We report measurements of this effect due to electron screening and compare these measurements to simulations. [Preview Abstract] |
Friday, June 8, 2012 11:42AM - 11:54AM |
U5.00007: The long time dynamics of a molecular ultracold plasma Hossein Sadeghi Esfahani, Jonathan Morrison, Nicolas Saquet, Markus Schulz-Weiling, Edward Grant Higher-order charged-particle interactions play a significant role in the creation and decay of a molecular ultracold plasma. Describing the forces at work requires the simultaneous consideration of plasma hydrodynamics and coupled collisional rate processes. Accordingly, we present model calculations that account for the effects of inelastic and reactive collisions on the spatial distribution of plasma density and associated hydrodynamic forces. As the plasma shape evolves to depart from a Gaussian sphere, the expanding electron gas exerts non-linear radial force on the ions, which creates a non-uniform radial hydrodynamic velocity field and causes further changes to plasma shape over time. Experimental data and simulation results show good agreement in decay parameters, but differ on expansion rate and thus electron temperature. [Preview Abstract] |
Friday, June 8, 2012 11:54AM - 12:06PM |
U5.00008: Ultracold neutral plasma resonant response to few-cycle radiofrequency pulses Truman Wilson, Wei-Ting Chen, Jacob Roberts Ultracold neutral plasmas exhibit a resonant response to applied radiofrequency (RF) fields in the frequency range of several MHz to hundreds of MHz for achievable densities. In typical experiments a single-frequency RF field is applied to the plasma as it expands. When the plasma density drops enough to be in resonance with the applied field, the resonant response is observed as an increase in electron evaporation rate. In contrast, we have conducted measurements where short bursts of RF were applied to the plasma, with pulse durations as short as two cycles studied in detail. We still observed a density-dependent resonant response with these short pulses. The usual description of the increase in evaporation rate being due to local resonant heating of electrons in the plasma is inconsistent with the timescale of the response and other factors. Instead, our results are consistent with rapid energy transfer from collective motion of the entire electron cloud to electrons in high-energy orbits. In addition to providing a potentially more robust way to measure ultracold neutral plasma densities, these measurements demonstrate the importance of collective motion in the energy transport and evaporation rate in these systems. [Preview Abstract] |
Friday, June 8, 2012 12:06PM - 12:18PM |
U5.00009: Creation and interrogation of a correlated molecular plasma Jonathan Morrison, Nicolas Saquet, Ed Grant Since the first realization of a correlated molecular plasma formed in a super-sonic beam expansion [1], much work has been devoted to characterizing fundamental parameters of the plasma: the ambipolar expansion rate is driven by electron kinetic energy and has been observed [2] to be lower than ultracold atomic plasmas produced in magneto-optical traps. Molecular dissipation mechanisms present a unique channel for directing energy away form electron kinetic energy. The importance of the entire Rydberg level manifold must be considered to accurately describe these systems [3], increasing the importance of molecular processes both at early, and later instances of the plasma lifetime. \\[4pt] [1] Morrison, J.P. \textit{et al}. Phys. Rev. Lett. \textbf{101} 205005, 2008.\\[0pt] [2] Morrison, J.P. \textit{et al}. Phys. Rev. A. \textbf{79} 062706, 2009.\\[0pt] [3] Morrison, J.P. \textit{et al}. J. Phys. B. \textbf{45} 025701, 2012. [Preview Abstract] |
Friday, June 8, 2012 12:18PM - 12:30PM |
U5.00010: Ultracold neutral plasmas at room temperature Joshua Wilson, Stephen Rupper, Daniel Thrasher, Nathan Heilmann, Scott Bergeson 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] |
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