Bulletin of the American Physical Society
46th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 60, Number 7
Monday–Friday, June 8–12, 2015; Columbus, Ohio
Session C2: Focus Session: Tests of Fundamental Physics |
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Sponsoring Units: GPMFC Chair: Brian Odom, Northwestern University Room: Union ABC |
Tuesday, June 9, 2015 2:00PM - 2:30PM |
C2.00001: Francis M. Pipkin Award Talk - Precision Measurement with Atom Interferometry Invited Speaker: Holger M\"uller Atom interferometers are relatives of Young's double-slit experiment that use matter waves. They leverage light-atom interactions to masure fundamental constants, test fundamental symmetries, sense weak fields such as gravity and the gravity gradient, search for elusive ``fifth forces,'' and potentially test properties of antimatter and detect gravitational waves. We will discuss large (multiphoton-) momentum transfer that can enhance sensitivity and accuracy of atom interferometers several thousand fold. We will discuss measuring the fine structure constant to sub-part per billion precision and how it tests the standard model of particle physics. Finally, there has been interest in light bosons as candidates for dark matter and dark energy; atom interferometers have favorable sensitivity in searching for those fields. As a first step, we present our experiment ruling out chameleon fields and a broad class of other theories that would reproduce the observed dark energy density. [Preview Abstract] |
Tuesday, June 9, 2015 2:30PM - 2:42PM |
C2.00002: Limits on dark energy scalars using atom interferometry Paul Hamilton, Matt Jaffe, Philipp Haslinger, Ethan Simmons, Justin Khoury, Holger M\"{u}ller Dark energy makes up 70\% of the mass-energy of the universe yet its identity remains unknown. Using atom interferometry we tightly constrain dark energy models based on scalar fields which become heavily screened in the presence of macroscopic matter. These ``chameleon'' fields were proposed as a form of quintessence which would be undetectable to macroscopic experiments searching for fifth forces. Combined with an ultra-high vacuum environment, the small mass of individual atoms prevents screening and makes them ideal test masses for detecting small forces from chameleons.\footnote{Burrage et al., arXiv:1408.1409} We use our recently developed optical cavity atom interferometer\footnote{Hamilton et al., arXiv:1409.7130, accepted to Phys. Rev. Lett.} to limit anomalous accelerations below $10^{-6} \textit{g}$ at millimeter-scale distances from a spherical source mass. This rules out a large range of chameleon theories consistent with the cosmological dark-energy density. With feasible improvements in sensitivity, we could detect chameleon fields with couplings up to the expected limit of the Planck mass scale. Adding a second source mass would also allow the measurement of the gravitational Aharonov-Bohm effect.\footnote{Hohensee et al., Phys. Rev. Lett. \textbf{108}, 230404 (2012)} [Preview Abstract] |
Tuesday, June 9, 2015 2:42PM - 2:54PM |
C2.00003: Testing the foundations of quantum mechanics with multi-path interferometers Robert Keil, Thomas Kauten, Thomas Kaufmann, Benedikt Pressl, Rene Heilmann, Alexander Szameit, Gregor Weihs Born's rule is one of the fundamental axioms of quantum mechanics and states that the probability density equates the squared magnitude of the wavefunction. Axioms in physics can't be theoretically proven, but only tested against experiments. Born's rule dictates the absence of higher order interference. Therefore, it can be tested by measuring the output signal of a multi-path interferometer with individually blockable paths. In this contribution, we present our latest results in this respect, improving previous experiments by two orders of magnitude in accuracy and precision. To this end, we implemented a five-path Mach-Zehnder interferometer in free space with improved power and phase stabilisation and increased photon flux. After compensating for the systematic effect of detector nonlinearities, we could bound the relative magnitude of higher order interferences to better than 10$^{\mathrm{-4}}$. In order to reduce this bound further, we have started working towards optically integrated interferometers, which promise reduced footprint and superior stability. Our first attempt in this direction is a semi-integrated solution. In this Michelson-configuration, external micromirrors are individually moved to modulate the effective transmission of each interferometer arm. We present our preliminary results obtained from this waveguide interferometer, discuss its current limitations and indicate ways to overcome them. [Preview Abstract] |
Tuesday, June 9, 2015 2:54PM - 3:06PM |
C2.00004: Atom Interferometry with Ultracold Quantum Gases in a Microgravity Environment Jason Williams, Jose D'Incao, Sheng-wey Chiow, Nan Yu Precision atom interferometers (AI) in space promise exciting technical capabilities for fundamental physics research, with proposals including unprecedented tests of the weak equivalence principle, precision measurements of the fine structure and gravitational constants, and detection of gravity waves and dark energy. Consequently, multiple AI-based missions have been proposed to NASA, including a dual-atomic-species interferometer that is to be integrated into the Cold Atom Laboratory (CAL) onboard the International Space Station. In this talk, I will discuss our plans and preparation at JPL for the proposed flight experiments to use the CAL facility to study the leading-order systematics expected to corrupt future high-precision measurements of fundamental physics with AIs in microgravity. The project centers on the physics of pairwise interactions and molecular dynamics in these quantum systems as a means to overcome uncontrolled shifts associated with the gravity gradient and few-particle collisions. We will further utilize the CAL AI for proof-of-principle tests of systematic mitigation and phase-readout techniques for use in the next-generation of precision metrology experiments based on AIs in microgravity. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. [Preview Abstract] |
Tuesday, June 9, 2015 3:06PM - 3:18PM |
C2.00005: Testing the quantum superposition principle: matter waves and beyond Hendrik Ulbricht New technological developments allow to explore the quantum properties of very complex systems, bringing the question of whether also macroscopic systems share such features, within experimental reach. The interest in this question is increased by the fact that, on the theory side, many suggest that the quantum superposition principle is not exact, departures from it being the larger, the more macroscopic the system [1]. Testing the superposition principle intrinsically also means to test suggested extensions of quantum theory, so-called collapse models. We will report on three new proposals to experimentally test the superposition principle with nanoparticle interferometry [2], optomechanical devices [3] and by spectroscopic experiments in the frequency domain [4, 5]. We will also report on the status of optical levitation and cooling experiments with nanoparticles in our labs, towards an Earth bound matter-wave interferometer to test the superposition principle for a particle mass of one million amu (atomic mass unit). \\[4pt] [1] Bassi, A., et al., Rev. Mod. Phys. 85, 471 (2013).\\[0pt] [2] Bateman, J., et al., Nat. Comm. 5, 4788 (2014).\\[0pt] [3] Xuereb, A. et al., Sci. Rep. 3, 3378 (2013)\\[0pt] [4] Bahrami, M. et al., Phys. Rev. Lett. 112, 210404 (2014)\\[0pt] [5] Bera, S. et al., Sci. Rep. 5, 7664 (2015) [Preview Abstract] |
Tuesday, June 9, 2015 3:18PM - 3:48PM |
C2.00006: Hunting for dark matter with GPS and atomic clocks Invited Speaker: Andrei Derevianko Atomic clocks are arguably the most accurate scientific instruments ever build. Modern clocks are astonishing timepieces guaranteed to keep time within a second over the age of the Universe. The cosmological applications of atomic clocks so far have been limited to searches of the uniform-in-time drift of fundamental constants. We point out that a transient in time change of fundamental constants (translating into clocks being sped up or slowed down) can be induced by dark matter objects that have large spatial extent, and are built from light non-Standard Model fields. The stability of this type of dark matter can be dictated by the topological reasons. We argue that correlated networks of atomic clocks, such as atomic clocks onboard satellites of the GPS constellation, can be used as a powerful tool to search for the topological defect dark matter. In other words, one could envision using GPS as a 50,000 km-aperture dark-matter detector. Similar arguments apply to terrestrial networks of atomic clocks. Details: A. Derevianko and M. Pospelov, Nature Phys. 10, 933 (2014) [Preview Abstract] |
Tuesday, June 9, 2015 3:48PM - 4:00PM |
C2.00007: Progress on the Global Network of Optical Magnetometers to search for Exotic physics (GNOME) D.F. Jackson Kimball, G. DeCamp, S. Thulasi, D. Fuentes, I. Viegas, S. Pustelny, P. Wlodarczyk, W. Gawlik, D. Budker, N. Leefer, A. Wickenbrock, S. Afach, L. Zhivun, C. Pankow, J. Smith, J. Read, R. Folman, M.P. Ledbetter, M. Pospelov, Y.K. Semertzidis, Y. Shin, T.W. Kornack, J. Stalnaker We discuss progress on the design and construction of a network of geographically separated, time-synchronized ultrasensitive atomic comagnetometers to search for correlated transient signals heralding new physics. The {\textbf{G}}lobal {\textbf{N}}etwork of {\textbf{O}}ptical {\textbf{M}}agnetometers to search for {\textbf{E}}xotic physics (GNOME) would be sensitive to nuclear and electron spin couplings to various exotic fields generated by astrophysical sources. To date, no such search has ever been carried out, making the GNOME a novel experimental window on new physics. A specific example of new physics detectable with the GNOME, presently unconstrained by astrophysical observations and laboratory experiments, is a network of domain walls of light pseudoscalar fields. [Preview Abstract] |
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