Bulletin of the American Physical Society
47th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 61, Number 8
Monday–Friday, May 23–27, 2016; Providence, Rhode Island
Session J5: Precision Measurements |
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Chair: Michael Romalis, Princeton University Room: 551AB |
Wednesday, May 25, 2016 2:00PM - 2:12PM |
J5.00001: Prospects for Lorentz- and CPT-violation searches with atomic spectroscopy experiments Arnaldo J. Vargas, V. Alan Kosteleck\'y It has been suggested that tiny deviations from Lorentz and CPT symmetry might be low-energy signals for a theory that correctly describes gravity at the quantum level. One interesting option is to use atomic spectroscopy experiments to search for these tiny deviations. The prospects for finding evidence for Lorentz violation in this way are studied within the framework of the Standard-Model Extension. The discussion considers commonly measured atomic transitions in experiments both with conventional matter and with more exotic atoms such as antihydrogen, muonium, and muonic hydrogen. Potential signals are identified and the relation between these signals and Lorentz-violation operators of arbitrary mass dimension is explained. Where available, constraints from existing data are obtained. [Preview Abstract] |
Wednesday, May 25, 2016 2:12PM - 2:24PM |
J5.00002: Lorentz- and CPT-violating signals in Penning traps Yunhua Ding, Alan Kosteleck\'y CPT and Lorentz symmetries are fundamental properties of the Standard Model. However, violation of these symmetries is possible in an underlying unified theory such as strings. This talk will focus on possible experimental effects for Lorentz and CPT violations. In particular, observable signals in measurements of anomaly and cyclotron frequencies of particles and antiparticles in a Penning trap will be discussed. New constraints from existing data will be presented and prospective sensitivities in future experiments will be outlined. [Preview Abstract] |
Wednesday, May 25, 2016 2:24PM - 2:36PM |
J5.00003: Strongly enhanced effects of Lorentz symmetry violation in highly charged ions Marianna Safronova, V. A. Dzuba, V. V. Flambaum, S.G. Porsev, T. Pruttivarasin, M. A. Hohensee, H. H\"affner It has been suggested that Lorentz symmetry may be violated in theories aiming at unifying gravity with other fundamental interactions. While the energy scale of such strongly Lorentz symmetry-violating physics is much higher than that currently attainable by particle accelerators, the observable, but extremely small, Lorentz-violating effects may appear in low-energy experiments carried out with very high precision. In the atomic experiments testing local Lorentz invariance (LLI) of the electron motion in Coulomb potential of a nucleus, one searches for variations of the atomic energy levels when the orientation of the electronic wave function is rotated with respect to the standard reference frame. We carried out a systematic theoretical investigation of the sensitivity of a wide range of atomic systems to LLI violation. We find large sensitivities to LLI violating physics in Yb$^+$ [1] and a number of highly charged ions that should allow improvements of LLI tests in the electron-photon sector by several orders of magnitude.\\ \noindent [1] V. A. Dzuba, V. V. Flambaum, M. S. Safronova, S. G. Porsev, T. Pruttivarasin, M. A. Hohensee, H. H\"{a}ffner, Nature Physics, advanced online publication, doi:10.1038/nphys3610 (2016). [Preview Abstract] |
Wednesday, May 25, 2016 2:36PM - 2:48PM |
J5.00004: QED calculations in heavy many-electron atoms and one-electron quasi-molecules I. I. Tupitsyn, M. S. Safronova, M. G. Kozlov, S. G. Porsev, V. M. Shabaev Construction of simple one-electron approach to one-loop QED operator is an important task for the relativistic quantum theory of atoms and molecules. In this work we used two modifications [1,2] of the model QED potential approach to calculations of the Lamb shift in many-electron atoms and one-electron quasi-molecules. The model potential is constructed as a sum of local and nonlocal (separable) potentials. The nonlocal part of the model potential was introduced to reproduce exactly the diagonal elements [2] and also off-diagonal elements [1] of the one-loop {ab initio} QED operator. The one-particle model QED operator was introduced in the Dirac-Fock and CI+MBPT relativistic calculations of the heavy and super-heavy atoms and in the calculations of the diatomic quasi-molecules. The comparison of the data obtained in different approaches to the one-loop QED operator is presented. Model QED potential is applied to calculate Lamb shift in the U$^{91+}$-U$^{92+}$ dimer. The results are compared with Ref. [3].\\ {[1]} V.M. Shabaev, I.I. Tupitsyn, and V.A. Yerokhin, Phys.~Rev.~A {\bf 88}, 012513 (2013).\\ {[2]} I.I. Tupitsyn and E.V. Berseneva, Opt. Spectrosc. {\bf 114}, 682, (2013).\\{[3]} A.N. Artemyev and A. Surzhykov, Phys.~Rev.~Lett. {\bf 114}, 243004 (2015). [Preview Abstract] |
Wednesday, May 25, 2016 2:48PM - 3:00PM |
J5.00005: Theory of force detection using optically levitated nanoparticles Brandon Rodenburg, Levi Neukirch, Robert Pettit, Nick Vamivakas, Mishkat Bhattacharya Levitated nanoparticles offer the potential of being incredibly well isolated from the environment. This isolation makes such systems excellent candidates for tests of quantum mechanics at the macroscale and as versatile platforms for ultrasensitive metrology. Systems involving an optical cavity mode to provide the trapping field, as well as cooling mechanism of the particle's center of mass motion are well understood theoretically and provide a canonical system for the field of quantum optomechanics. However, techniques based on measurement based parametric cooling and feedback stabilization have made it possible to trap and manipulate a nanoparticle without the need for an optical cavity, even at extremely high vacuum where gas damping cannot stabilize the motion of the particle. For these cavityless systems, a fully quantum theory has recently been developed. In this talk we will present recent work that we have carried out to apply this theory to the use of such devices as force sensors, including a discussion of the ultimate limits placed on the sensitivity by the sources of fundamental quantum noise. [Preview Abstract] |
Wednesday, May 25, 2016 3:00PM - 3:12PM |
J5.00006: In Situ Magnetic Field Measurement using the Hanle Effect Jarom Jackson, Dallin Durfee We have developed a simple method of in situ magnetic field mapping near zero points in magnetic fields. It is ideal for measuring trapping parameters such the field gradient and curvature, and should be applicable in most experiments with a magneto-optical trap (MOT) or similar setup. This method works by probing atomic transitions in a vacuum, and is based on the Hanle effect, which alters the polarization of spontaneous emission in the presence of a magnetic field. Unlike most techniques based on the Hanle effect, however, we look only at intensity. Instead of measuring polarization we use the change in directional radiation patterns caused by a magnetic field. Using one of the cooling beams for our MOT, along with a linear polarizer, a narrow slit, and an inexpensive webcam, we measure the three dimensional position of a magnetic field zero point within our vacuum to within ±1 mm and the gradient through the zero point to an accuracy of 4%. [Preview Abstract] |
Wednesday, May 25, 2016 3:12PM - 3:24PM |
J5.00007: Progress Towards the Detection of Faraday Rotation on Spin Polarized $^{\mathrm{\mathbf{3}}}$\textbf{He} Joshua Abney, Mark Broering, Wolfgang Korsch Off-resonance Faraday rotation can offer a method to measure the nuclear spin optical rotation of the $^{\mathrm{3}}$He nucleus and gain access to new information about the atomic polarizability of the Helium atom. The interaction of the polarization state of light with the nuclear spin of the helium atom is very weak and has never been detected. A sensitive triple modulation technique has been developed which can detect the expected rotation angle on the order of 100 nrad. Once a Faraday rotation signal is observed, the next step is to separate the magnetic and electric contributions to the rotation by utilizing their different frequency dependencies. Recent studies involved optimizing several parameters which impact $^{\mathrm{3}}$He target polarization. Progress towards detecting nuclear spin optical rotation on $^{\mathrm{3}}$He will be reported. [Preview Abstract] |
Wednesday, May 25, 2016 3:24PM - 3:36PM |
J5.00008: Bloch oscillations for large momentum transfer and high precision in an ytterbium Bose-Einstein condensate interferometer. Benjamin Plotkin-Swing, Katherine McAlpine, Daniel Gochnauer, Brendan Saxberg, Subhadeep Gupta The narrow momentum and position spread of a Bose-Einstein condensate (BEC) can help improve atom interferometric measurements. In earlier work, we demonstrated a contrast interferometer with ytterbium (Yb) BECs\footnote{A.O. Jamison, B. Plotkin-Swing, S. Gupta, Phys. Rev. A 90, 06}. Here, we report progress towards implementing a second generation Yb BEC interferometer with the goal of measuring h/m, where h is Planck's constant and m is the mass of a Yb atom, in order to determine the fine structure constant $\alpha$. The use of the non-magnetic Yb atom and the symmetric geometry of the interferometer make the measurement immune to several error sources. We have produced Yb BECs in a new apparatus, and are currently installing and testing the laser pulse atom-optics needed for the interferometry sequence. The precision of our measurement scales with N$^{2}$, where 2N is the number of photon recoils separating the interfering momentum states in the interferometer. We will discuss our progress towards realizing Bloch oscillations (BO) pulses for large N. Using an extension of our previous analysis$^{2}$, we will also discuss the role of diffraction phases in our interferometer due to the BO pulses. [Preview Abstract] |
Wednesday, May 25, 2016 3:36PM - 3:48PM |
J5.00009: Measuring the fine structure constant with Bragg diffraction and Bloch oscillations Chenghui Yu, Brian Estey, Richard Parker, Jordan Dudley, Holger Müller We have demonstrated a new scheme for atom interferometry based on large-momentum-transfer Bragg beam splitters and Bloch oscillations [1]. In this new scheme, we have achieved a resolution of $\delta\alpha/\alpha$=0.25ppb in the fine structure constant measurement, which gives up to 4.4 million radians of phase difference between freely evolving matter waves. We have suppressed many systematic effects known in most atom interferometers with Raman beam splitters such as light shift, Zeeman effect shift as well as vibration. We have also simulated multi-atom Bragg diffraction to understand sub-ppb systematic effects, and implemented spatial filtering to further suppress systematic effects. We present our recent progress toward a measurement of the fine structure constant, which will provide a stringent test of the standard model of particle physics. [1] Estey et al., PRL 115, 083002 (2015). [Preview Abstract] |
Wednesday, May 25, 2016 3:48PM - 4:00PM |
J5.00010: Atomic ionization due to dark matter scattering on electrons: Implications for DAMA and XENON interpretation Benjamin Roberts, Yevgeny Stadnik, Vladimir Dzuba, Victor Flambaum, Gleb Gribakin, Maxim Pospelov Atoms can become ionized during the scattering of a particle off a bound electron. Such interactions involving WIMP dark matter are a potential explanation for the anomalous $9\sigma$ annual modulation in the DAMA direct detection experiment 1. Conventional wisdom has it that the amplitude for such a process should be exponentially small. We show, however, that due to nonanalytic, cusp-like behaviour of Coulomb functions close to the nucleus this suppression is removed, leading to an effective atomic structure enhancement. Crucially, we show that due to this behavior, the electron relativistic effects give the dominant contribution to such a process, enhancing the cross section by orders of magnitude 2. Ab initio relativistic calculations are therefore necessary for the proper analysis of such a problem. Therefore, we perform high-accuracy relativistic calculations of atomic ionization. We scan the parameter space: the DM mass, the mediator mass, and the effective coupling strength, to determine if there is any region that could potentially explain the DAMA signal 3.~\\ 1. Bernabei et al., Eur.Phys.J.C 73, 2648 (2013); 2. Roberts et al., Phys.Rev.Lett. 116, 023201 (2016); 3. Roberts et al., In Prep. [Preview Abstract] |
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