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 B8: Focus Session: Fundamental Constants |
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Sponsoring Units: GPMFC Chair: Mikhail Kozlov, PNPI Gatchina Russia Room: Franklin CD |
Tuesday, June 9, 2015 10:30AM - 11:00AM |
B8.00001: Fundamental Constants and Tests with Simple Atoms Invited Speaker: Joseph Tan Precise measurements with simple atoms provide stringent tests of physical laws, improving the accuracy of fundamental constants---a set of which will be selected to fully define the proposed New International System of Units. This talk focuses on the atomic constants (namely, the Rydberg constant, the fine-structure constant, and the proton charge radius), discussing the impact of the proton radius obtained from the Lamb-shift measurements in muonic hydrogen [A. Antognini, \textit{et al}., Science \textbf{339}, 417 (2013)]. Significant discrepancies persist despite years of careful examination: the slightly smaller proton radius obtained from muonic hydrogen requires the Rydberg constant and the fine-structure constant to have values that disagree significantly with the CODATA recommendations. After giving a general overview, I will discuss our effort to produce one-electron ions in Rydberg states, to enable a different test of theory and measurement of the Rydberg constant. [Preview Abstract] |
Tuesday, June 9, 2015 11:00AM - 11:12AM |
B8.00002: Towards an improved measurement of the proton size from precision spectroscopy of atomic hydrogen Lothar Maisenbacher, Axel Beyer, Ksenia Khabarova, Arthur Matveev, Randolf Pohl, Thomas Udem, Theodor W. H\"{a}nsch, Nikolai Kolachevsky Precision spectroscopy of atomic hydrogen has long been successfully used to provide stringent tests on fundamental theories and precisely determine physical constants. The current limit originates from the uncertainty in the value of the proton r.m.s.$\,$charge radius $r_p$. Moreover, the value of $r_p$ extracted from laser spectroscopy of muonic hydrogen\footnote{R. Pohl et al., Nature 466, 213 (2010)} is ten times more accurate than any other determination, but disagrees by 7$\sigma$ with the recommended CODATA 2010 value. Here, we report on our progress towards an improved absolute frequency measurement of the 2S-4P (one-photon) transition in atomic hydrogen, which combined with the much more precisely known 1S-2S transition frequency\footnote{C.\,G. Parthey et al., PRL 107, 203001 (2011)} allows a more precise extraction of $r_p$ from electronic hydrogen. To suppress the first order Doppler shift, we use a cryogenic beam of atoms optically excited to the 2S state and actively stabilized counter-propagating laser beams. Interference effects due to spontaneous emission\footnote{M. Horbatsch and E.$\,$A. Hessels, PRA 82, 052519 (2010)} were studied and we show how to experimentally suppress the corresponding line center shifts. [Preview Abstract] |
Tuesday, June 9, 2015 11:12AM - 11:24AM |
B8.00003: Progress towards measuring the $2S_{1/2}$ to $2P_{1/2}$ interval in hydrogen A.C. Vutha, N. Bezginov, I. Ferchichi, E.A. Hessels There is a large discrepancy between the CODATA value for the proton charge radius, and its determinations from muonic hydrogen measurements. This discrepancy is referred to as the \emph{proton radius puzzle}. Improved measurements on atomic hydrogen can elucidate the origins of this discrepancy. We have constructed an experiment to measure the Lamb shift ($n=2, S_{1/2} \to P_{1/2}$) in a fast beam of atomic hydrogen. Using a novel separated-oscillatory-fields method and high signal-to-noise ratio detection, we can measure the center of this transition with a statistical uncertainty approaching $10^{-5}$ of its natural linewidth. We report on our studies of systematic effects, and on our progress towards a new measurement of the proton charge radius. [Preview Abstract] |
Tuesday, June 9, 2015 11:24AM - 11:36AM |
B8.00004: Progress towards measuring the Rydberg Constant Using Circular Rydberg Atoms in an Intensity-Modulated Optical Lattice Andira Ramos, Kaitlin Moore, Georg Raithel Recent significant disagreement with the previously established size of the proton demonstrates a need to reconsider the current value of the Rydberg constant, the effects of the nuclear charge distribution and QED in hydrogen-like atoms. An experiment is in progress to obtain a measurement of the Rydberg constant by studying circular Rydberg atoms, which exhibit very small QED shifts and electron wavefunctions which do not overlap with the nucleus. Cold Rydberg atoms are trapped using a ponderomotive potential. To drive the transitions, a novel type of spectroscopy is used which utilizes an optical-lattice field that is intensity-modulated at the frequencies of atomic transitions [1]. The method is free of typical spectroscopic selection rules and has been shown to drive transitions up to fifth order [2]. Combined with optical Rydberg-atom trapping, the method enables the measurement of narrow, sub-THz transitions between long-lived circular Rydberg levels. Energy shifts affecting this precision measurement will also be discussed. \\[4pt] [1] K.R. Moore, S.E. Anderson, G. Raithel;~Forbidden atomic transitions driven by an intensity-modulated laser trap. Nature Communications~(FIX)\\[4pt] [2] K.R. Moore, G. Raithel; Nonlinear and Magic Ponderomotive Spectroscopy (in preparation). [Preview Abstract] |
Tuesday, June 9, 2015 11:36AM - 12:06PM |
B8.00005: Precision measurements in gravitational physics with cold atom interferometry Invited Speaker: Guglielmo M. Tino I will describe experiments we are conducting for precision tests of gravitational physics using cold atom interferometry. In particular, I will report on the measurement of the Newtonian gravitational constant [1] and of the gravity-field curvature [2] with a Rb Raman interferometer, and on experiments based on Bloch oscillations of Sr atoms in optical lattices for gravity measurements at small spatial scales [3] and for testing the Einstein equivalence principle [4]. Future prospects for experiments in space will be also discussed [5]. \\[4pt] [1] G. Rosi, F. Sorrentino, L. Cacciapuoti, M. Prevedelli, G. M. Tino, \textit{Precision Measurement of the Newtonian Gravitational Constant Using Cold Atoms}, Nature 510, 518 (2014).\\[0pt] [2] G. Rosi, L. Cacciapuoti, F. Sorrentino, M. Menchetti, M. Prevedelli, G. M. Tino, \textit{Measurement of the gravity-field curvature by atom interferometry}, Phys. Rev. Lett. 114, 013001 (2015)\\[0pt] [3] F. Sorrentino, A. Alberti, G. Ferrari, V. V. Ivanov, N. Poli, M. Schioppo, G. M. Tino, \textit{Quantum sensor for atom-surface interactions below 10 }$\mu m$, Phys. Rev. A 79, 013409 (2009).\\[0pt] [4] M.G. Tarallo, T. Mazzoni, N. Poli, D.V. Sutyrin, X. Zhang, G. M. Tino, \textit{Test of Einstein Equivalence Principle for 0-Spin and Half-Integer-Spin Atoms: Search for Spin-Gravity Coupling Effects}, Phys. Rev. Lett. 113, 023005 (2014).\\[0pt] [5] G. M. Tino et al., \textit{Precision Gravity Tests with Atom Interferometry in Space}, Nuclear Physics B (Proc. Suppl.) 243--244, 203 (2013). [Preview Abstract] |
Tuesday, June 9, 2015 12:06PM - 12:18PM |
B8.00006: Quantum Tests of the Universality of Free Fall Dennis Schlippert, Henning Albers, Christian Meiners, Logan L. Richardson, Etienne Wodey, Hendrik Heine, Dipankar Nath, Christian Schubert, Wolfgang Ertmer, Ernst M. Rasel Searches for violations of the Universality of Free Fall (UFF) mark an important approach in reconciling quantum mechanics and general relativity. In this respect, matter wave interferometers resemble a novel test method that differs fundamentally from experiments employing macroscopic test masses. We report on a quantum test of the UFF at the 100 ppb level using two different chemical elements, \textsuperscript{39}K and \textsuperscript{87}Rb [1]. We show recent improvements of the experiment aiming towards a ppb test, focusing on both, the stability, and the systematic uncertainty aided by the use of a common optical dipole trap. We furthermore present future strategies for tests of the UFF aiming for accuracies of $10^{-13}$ and beyond in large scale apparatuses on ground and in space.\\[4pt] [1] D. Schlippert \emph{et al.,} \emph{Phys. Rev. Lett.} \textbf{112,} 203002 (2014) [Preview Abstract] |
Tuesday, June 9, 2015 12:18PM - 12:30PM |
B8.00007: Simultaneous Dual-Species Atom Interferometry Alexis Bonnin, Nassim Zahzam, Yannick Bidel, Alexandre Bresson In the context of testing the Weak Equivalence Principle (WEP) with matter-wave accelerometers, some projects under development aim to compare the acceleration of two different atomic species during few seconds of free fall in order to achieve highly sensitive measurements.\footnote{S. Dimopoulos et al., Phys. Rv. Lett. 98, 111102 (2007)}$^,$\footnote{H. M\"{u}ntiga et al., Phys Rev. Lett. 110, 093602 (2013)}$^,$\footnote{R. Geiger et al., Nature Commun. 2, 474 (2011)} A simultaneous interrogation of both atomic species is crucial to fully take advantage of a differential measurement. We report the realization of an atom interferometer based on Raman transitions which simultaneously interrogates both isotopes of Rubidium.\footnote{A. Bonnin et al., Phys. Rev. A 88, 043615 (2013)} The simultaneous aspect of our experiment allows the resolution of the differential accelerometer to remain lower than 7.10$^{-9}g$ even with vibration levels up to 3.10$^{-3}g$ thanks to common-mode vibration noise rejection. These results exhibit a rejection ratio of 90 dB. An atom based test of the WEP has been carried out leading to a differential free fall measurement between both isotopes of $\Delta g/g=(1.2 \pm 3.2)\times 10^{-7}$. [Preview Abstract] |
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