Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session B09: Precision Tests of Physics Laws |
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Sponsoring Units: GPMFC DAMOP Chair: Dima Budker, UC-Berkeley/Mainz Room: Sheraton Governor's Square 11 |
Saturday, April 13, 2019 10:45AM - 10:57AM |
B09.00001: JILA’s search for the electron electric dipole moment (eEDM): constraining beyond Standard Model physics and time-varying eEDM Tanya S. Roussy, William B. Cairncross, Daniel N. Gresh, Matthew Grau, Kevin C. Cossel, Yan Zhou, Jun Ye, Eric A. Cornell We have performed a measurement of the electron’s permanent electric dipole moment (eEDM) using trapped molecular ions polarized in rotating bias fields. Our initial analysis of the data yielded a mean consistent with zero, assuming no time-variation in the signal. We have recently re-analyzed the data to constrain possible oscillations in the signal over eight orders of magnitude in frequency. This re-analysis allows us to constrain the mass of the hypothetical axion, which (if present) would generate an oscillatory signal in the eEDM channel. In this talk, I will review the essence of our measurement as well as our most recent re-analysis. |
Saturday, April 13, 2019 10:57AM - 11:09AM |
B09.00002: Towards a more sensitive measurement of the permanent electric dipole moment of Radium-225 Roy A Ready Ra-225 is expected to have a greatly enhanced sensitivity to its permanent atomic electric dipole moment (EDM) arising from violation of combined charge-conjugation (C) and parity (P) transformation, and, assuming CPT symmetry, time (T) violation due to its octupole-deformed nucleus. A proof-of-principle measurement of the upper limit of the Ra-225 EDM was carried out in 2014 (PRL 114 233002) and an improved measurement followed in June 2015 (PRC 94 025501). There are three main experimental upgrades that can collectively contribute to a much more sensitive EDM measurement. This work updates the status of the electric field upgrade. Radium atoms are vaporized, trapped, and transported into a science chamber with controlled magnetic and electric fields between two high voltage electrodes in the Ra EDM experimental apparatus at Argonne National Laboratory (ANL). Recently, a new pair of niobium electrodes was conditioned and validated at Michigan State University (MSU) and installed in the apparatus, replacing the original electrodes. |
Saturday, April 13, 2019 11:09AM - 11:21AM |
B09.00003: Towards a search for non-Newtonian gravity with optically-levitated microspheres Charles P Blakemore, Alexander D Rider, Akio Kawasaki, Nadav Priel, Alexander Fieguth, Sandip Roy, Giorgio Gratta The universal law of gravity has undergone stringent tests for more than a century, over length scales ranging from the atomic to the planetary. Of particular interest is the short distance regime, where modifications to Newtonian gravity may arise from axion-like particles and extra dimensions, while constraints on such explanations are mild. We have constructed a precision force sensor based on optically-levitated microspheres with a force sensitivity of ∼10-17 N/√Hz, sufficient to increase the sensitivity of searches for non-Newtonian forces in the 1-100 μm range. Toward a measurement of the gravitational force and its possible modifications, we present results describing a novel trapping system and optics, and the characterization of the levitated microsphere test mass. Various control schemes inherent to the system, such as its 3D force sensitivity and electrically driven microsphere rotation, are also discussed, as they may reduce the effects of background forces. |
Saturday, April 13, 2019 11:21AM - 11:33AM |
B09.00004: A Microfluidic Approach to Producing Gravitational Masses for an Optically Levitated Force Sensor Andrew Kilby, Elizabeth C van Assendelft, Gadi Afek, Alec Emser, Sumita Ghosh, Wenqiang Li, Fernando Monteiro, David C Moore Recent experiments have used optically levitated microspheres in high vacuum to study fundamental forces with novel precision. We describe our search for non-Newtonian gravity at the micron scale using such a force sensor. In particular, we report on our development of a microfluidics-based method for producing a controlled gravitational field. This method yields a monodisperse, mesoscopic emulsion of low-density oil droplets in a higher-density aqueous phase. We report both on our control of this system, as well as our precision limits in optically measuring it in vacuum. |
Saturday, April 13, 2019 11:33AM - 11:45AM |
B09.00005: Room temperature optomechanical squeezing Nancy Aggarwal Quantum fluctuations of light impose a fundamental limit precision optical measurements, laser interferometric detection of gravitational waves (GWs), for example. Current generation GW detectors are limited by quantum noise and plan to improve their sensitivity by injecting squeezed states of light generated by non-linear optical materials. We present an alternative technology for producing squeeze states of light using the radiation pressure interaction of light with a mechanical oscillator. Such optomechanical (OM) squeezed light sources would be widely applicable for future precision measurements because their non-linearity is independent of the laser wavelength. Previously, OM squeezers were limited to cryogenic temperatures. I will present our recent measurement of squeezed light from an OM system at room temperature [1]. Operation of a quantum OM system at room temperature not only makes its integration into complex interferometers more feasible, it also provides a resource for exploring quantum light-matter interactions in a human-perceivable environment.
[1]: https://arxiv.org/abs/1812.09942 |
Saturday, April 13, 2019 11:45AM - 11:57AM |
B09.00006: Progress toward a precessing ferromagnetic needle magnetometer for ultrasensitive torque measurements Tao Wang, Sean Lourette, Sean R O'Kelley, Matin Kayci, Yehuda Benzion Band, Dmitry Budker, Derek F Jackson Kimball, Alexander Sushkov A ferromagnetic needle is predicted to precess about the magnetic field axis at a Larmor frequency Ω when IΩ << Nħ, where I is the moment of inertia of the needle and N is the number of polarized spins in the needle. In this regime the needle behaves as a gyroscope with spin Nħ maintained along the easy axis of the needle by the crystalline and shape anisotropy. If the needle is sufficiently isolated from the environment, a measurement of precession can yield sensitivity to torques well beyond that of existing techniques. Levitation of a micron-scale ferromagnetic particle above a superconductor is one possible method of near frictionless suspension enabling observation of ferromagnetic needle precession and ultrasensitive torque measurements. We discuss experimental investigations of the dynamics of a micron-scale ferromagnetic particle levitated above a superconducting niobium surface with this goal in mind. |
Saturday, April 13, 2019 11:57AM - 12:09PM |
B09.00007: A Laser Heterodyne Polarimeter to Search for VMB with ALPS IIc Hardware Harold Hollis, Gabriel Alberts, Giuseppe Messineo, D. B. Tanner, Guido Mueller An unconfirmed prediction of QED, dating from 1936, is that light propagates with a polarization dependent speed v ≠ c through a background magnetic field, and the resulting vacuum magnetic birefringence (VMB) scales with B2. We describe an experiment for the measurement of VMB and report the early development and testing status of a very sensitive polarimeter. We also outline a full-scale VMB experiment at DESY leveraging the ALPS IIc 100 m high finesse optical cavities and HERA magnet strings. |
Saturday, April 13, 2019 12:09PM - 12:21PM |
B09.00008: Is the Electron Orbital Gyromagnetic Factor Exactly Equal to 1? Ayodeji M Awobode High precision measurements and calculations of the hyperfine and fine structure of the hydrogen atom spectrum were crucial to the development of Quantum Field Theory (QED). High precision measurement of the magnetic moment of the electron have subsequently been important in the testing of QED, with much effort devoted to the accurate measurement of the anomaly (gS – 2) in the spin gyromagnetic factor gS. The g-factor for the electron’s spin magnetic moment gS has been measured to a precision of 2.8 parts in 1013. The spin g-factor is the ratio of the magnetic moment to the spin angular momentum S, measured in units of the Bohr magneton mB. Its agreement with the prediction of Quantum Field Theory provides the most precise confirmation of theory with experiment in all of physics. In contrast, the orbital g-factor gL is known only to about 1 part in 104. Experiments will be described to measure gL to much higher precision and preliminary calculations of relativistic corrections to gL will be presented. Finally, a conceptual analysis of relativistic quantum mechanics will be presented, with comments on the steps needed to calculate gL. |
Saturday, April 13, 2019 12:21PM - 12:33PM |
B09.00009: Relativity, Curved Space-Times, and the Dirac Equation for Atomic Systems Ulrich D Jentschura This talk attempts to contribute to the discussion, and in part, answer, the following questions: Does the equivalence principle hold for antiparticles? Is general relativity compatible with quantum mechanics, and if not, where are the limits of "compatibility"? What kind of gravitational effects could be seen in high-precision spectroscopy, and in g factor measurements, where the experimental accuracy is absolutely stupendous? How can we couple the Dirac equation to curved space-times? Can we observe gravitational, position-dependent effects in atomic physics as opposed to g factor measurements, and would these lead to tiny violations of the Einstein equivalence principle? The talk is based on calculations reported in [Phys. Rev. A vol. 98, 032508 (2018)]. |
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