Bulletin of the American Physical Society
39th Annual Meeting of the APS Division of Atomic, Molecular, and Optical Physics
Volume 53, Number 7
Tuesday–Saturday, May 27–31, 2008; State College, Pennsylvania
Session I3: Focus Session: Searches for Relativity Violations (Co-Sponsored by GPMFC) |
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Chair: Neil Russell, Northern Michigan University Room: Keller Building 104 |
Thursday, May 29, 2008 8:00AM - 8:36AM |
I3.00001: Theory and Status of Lorentz Violation Invited Speaker: Einstein's theories of special and general relativity are a key component of our best existing description of nature at the fundamental level. However, tiny deviations from the laws of relativity could arise from a unified theory of quantum physics and gravity. The resulting experimental effects are described by a theory called the Standard-Model Extension. The SME predicts observable signals now being sought in a variety of experiments using high-sensitivity AMO techniques. In this talk, some basic ideas about relativity violations will be described and a status report on the experimental searches will be given. [Preview Abstract] |
Thursday, May 29, 2008 8:36AM - 8:48AM |
I3.00002: Searching for Lorentz violation with new Ives-Stilwell tests Michael Hohensee, David F. Phillips, Ronald L. Walsworth Ives-Stilwell measurements have been used to measure relativistic time dilation effects and place constraints upon directional and frame-dependent anisotropies of the speed of light. Over the past seventy years, great improvements have been made upon the original 1938 experiment of Ives and Stilwell, but are now approaching the practical limits of what can be achieved by such tests at reasonable scales. Common to every measurement has been reliance upon optical transitions and continuous wave spectroscopy. We propose using coherent two-photon processes and coherent pulsed spectroscopic techniques to move beyond existing scaling limits. [Preview Abstract] |
Thursday, May 29, 2008 8:48AM - 9:00AM |
I3.00003: Atom interferometric test of the isotropy of Post-Newtonian gravity. Sheng-wey Chiow, Sven Herrmann, Holger Mueller, Steven Chu We present a test of the local Lorentz invariance of post-Newtonian gravity by monitoring Earth's gravity with a Mach-Zehnder atom interferometer. The interferometer is realized in an atomic fountain that launches Cs-atoms, cooled by Raman sideband cooling in an optical lattice. With pulse separation times of 400\,ms, a resolution of up to $8 \times 10^{-9}\,$g$/\sqrt{Hz}$ was obtained, the highest reported so far. Here we analyze a continuous 60\,h measurement of the local gravitational acceleration g obtained from this setup and two measurement runs from a previous setup (A. Peters et al. Metrologia 38, 2001). In addition to the modulation of local g due to tidal forces, we search for a modulation of local g with Earth's rotation as it would be caused by anisotropic gravity. Expressed within the standard model extension (SME) or Nordtvedt's anisotropic universe model, the analysis limits four coefficients describing anisotropic gravity at the ppb level and three others, for the first time, at the 10\,ppm level. Also, we use the SME to explicitly include possible violation of Lorentz invariance in electrodynamics. This demonstrates how the experiment actually compares the isotropy of two sectors of the SME, i.e. gravity and electromagnetism. [Preview Abstract] |
Thursday, May 29, 2008 9:00AM - 9:12AM |
I3.00004: Gravitationally Coupled Atoms as a Probe of Lorentz Symmetry Jay D. Tasson, V. Alan Kostelecky A feasible means of searching for new physics at the Planck scale is provided by possible violations of Lorentz symmetry. At our present low energies, effects of such violations are described by the Standard-Model Extension (SME). In this talk, I will discuss new sensitivities to Lorentz violation stemming from gravitational couplings in the fermion sector of the SME. Such sensitivities are attainable in several experiments, including atom interferometer and Equivalence Principle tests. [Preview Abstract] |
Thursday, May 29, 2008 9:12AM - 9:48AM |
I3.00005: Modern Optical Tests of Special Relativity Invited Speaker: ``The speed of light is finite and does not depend on the motion of either source or observer''. This is the fundamental statement underlying Albert Einstein's theory of Special Relativity. First formulated early in the 20th century, this theory now is one of the cornerstones of our scientific understanding of the world and tightly woven into the fabric of modern physical theories. Due to this outstanding role, it always has been of prime importance to experimentally verify the validity of the underlying theory. Today, further incentive for such tests is provided by new theoretical attempts -- such as string theory or loop quantum gravity -- aiming at unifying the forces of nature, which indeed suggest small violations of Lorentz-Invariance. This talk will discuss modern tests based on optical methods, which are especially well suited for the task at hand. A specific example is a modern version of the classic Michelson-Morley experiment testing the isotropy of light propagation, where the measurement is performed by monitoring the resonance frequency of an optical resonator continuously rotating on a precision turntable. This currently allows a sensitivity at the $\Delta c / c = 10^{-17}$ level for a direction dependent variation of the speed of light, with the potential for improvements in precision by up to three orders of magnitude in the near future. [Preview Abstract] |
Thursday, May 29, 2008 9:48AM - 10:00AM |
I3.00006: New Limits on Coupling of Fundamental Constants to Gravity by Absolute Frequeny Measurements of $^{87}$Sr Optical Lattice Clocks Sebastian Blatt, Gretchen K. Campbell, Andrew D. Ludlow, Jan W. Thomsen, Michael J. Martin, Martin M. Boyd, Jun Ye We have measured the $^{87}$Sr ${{^1}\mathrm{S}_0}$-${{^3}\mathrm{P}_0}$ clock transition at $\nu_{\mathrm{Sr}} = 429\,228\,004\,229\,873.83\pm 0.37$~Hz, limited by statistical uncertainty of the Sr/Cs comparison. Three international laboratories agree on the absolute frequency at the $1\times 10^{-15}$ (Boulder, Paris) to $4\times 10^{-15}$ (Boulder, Paris, Tokyo) level, making $\nu_{\mathrm{Sr}}$ the best agreed-upon optical frequency to date. We analyze the global Sr frequency record to test Local Position Invariance by obtaining the best limits to date on coupling of fundamental constants to the ambient gravitational potential. [Preview Abstract] |
Thursday, May 29, 2008 10:00AM - 10:12AM |
I3.00007: Molecular Optical Lattice Clock Tanya Zelevinsky, Svetlana Kotochigova, Jun Ye Ultracold homonuclear molecules present a model-independent system for precision measurements, such as tests of time variations of the proton-electron mass ratio. These measurements would complement those utilizing atomic clocks or astronomical observations. Creation and manipulation of dimers based on ultracold bosonic alkaline-earth-metal atoms appears particularly attractive due to the simplicity of the zero-spin ground state molecular potentials. Furthermore, recent success with precision and accuracy of optical lattice clocks based on these atoms shows the potential of achieving extremely low systematic uncertainties in the tight-confinement regime in the lattice. We discuss specific schemes for obtaining the cold molecular sample, including the magic-frequency optical lattice technique for molecular vibrational transitions. [Preview Abstract] |
Thursday, May 29, 2008 10:12AM - 10:24AM |
I3.00008: Cavity Tests of Higher-Order Lorentz Violation Matthew Mewes Resonant cavities provide some of the best tests of Lorentz invariance in electromagnetism. In the past, experiments have primarily focused on low-order Lorentz-violating operators of renormalizable dimension. New work has extended the existing phenomenology to operators of arbitrary dimension. In this talk, I will discuss potential searches for these new higher-order violations of Lorentz invariance using electromagnetic resonant cavities. [Preview Abstract] |
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