Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session P01: Precision measurements for fundamental physics, interferometry, and trapped ions |
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Sponsoring Units: DAMOP Chair: Norman Yao, University of California, Berkeley Room: 103 |
Wednesday, March 4, 2020 2:30PM - 2:42PM |
P01.00001: JILA’s search for the electron’s electric dipole moment: a novel approach to searches for new physics Tanya Roussy, William B Cairncross, Daniel A Palken, Benjamin M Brubaker, Daniel N Gresh, Matthew Grau, Kevin Cossel, Kia Boon Ng, Yuval Shagam, Yan Zhou, Victor Flambaum, Jun Ye, Eric A. Cornell We are probing TeV-scale physics with a unique tabletop experiment which combines trapped molecular ions, rotating bias fields, orientation-resolved detection, and over a dozen lasers to both measure the electron’s electric dipole moment and constrain potential dark matter candidates. In this talk I will introduce the essence of our measurement as well as our methods for constraining both dark matter and parity-violating physics. |
Wednesday, March 4, 2020 2:42PM - 2:54PM |
P01.00002: Towards a More Sensitive Measurement of the Atomic Electric Dipole Moment of Radium-225 Roy Ready, Kevin Bailey, Michael N Bishof, Donald William Booth, Matthew R Dietrich, Peter Mueller, Thomas O'Connor, Tenzin Rabga, Jaideep Singh Permanent atomic electric dipole moments (EDMs) violate parity (P) and time reversal (T), and, assuming CPT symmetry, combined charge-conjugation and parity transformation (CP). Observable EDMs are enhanced in large-Z atoms with octupole-deformed, or pear-shaped, nuclei. Radium-225 has a significantly larger octupole deformation than nuclei used in other EDM experiments. In the Ra EDM experiment, radium atoms are vaporized, slowed, trapped, and transported to a science chamber between two high voltage electrodes. The first measurements of the upper limit of the EDM of Radium-225 were carried out in 2014 and 2015. For the second generation of measurements (2019—2020), upgrades to the atom detection method and applied electric field magnitude will improve our measurement sensitivity by up to two orders of magnitude. Additionally, we validated plans for a better longitudinal atom slower by experimentally verifying critical theorized branching ratios. The new slower is expected to provide an order of magnitude improvement in measurement sensitivity. |
Wednesday, March 4, 2020 2:54PM - 3:06PM |
P01.00003: Modeling a dual-Sagnac interferometer for rotation sensing Charles Henry, Stephen G Thomas, Robert Sapp, Charles Clark, Mark Edwards A recent experiment1, performed in the group of Cass Sackett, implemented a dual Sagnac interferometer for rotation sensing using a Bose-Einstein condensate confined in an harmonic potential. The condensate is first split into two pieces using standing-wave Bragg lasers and then allowed to fly apart until the two pieces come to a stop. These two pieces are then split again along a perpendicular direction creating two pairs of condensates moving around a circle in opposite directions. They re-overlap after one trip around the circle at which point they are split a third time and the number of stationary atoms is measured. We have simulated this experiment using a a model based on the Lagrangian Variational Method where the condensate pieces are represented by Gaussian clouds. We have mapped out the region of validity of this model by direct numerical simulation using the 3D Gross-Pitaevskii equation. In addition to performing simulations under experimental conditions where the number of atoms was N=104, we also simulated the interferometer operation for larger condensates where atom-atom interactions must be accounted for. |
Wednesday, March 4, 2020 3:06PM - 3:18PM |
P01.00004: Mechanism for producing smooth flow by stirring a racetrack BEC Mark Edwards, Daniel Fogarty, Charles Clark We studied the production of smooth flow in a Bose-Einstein-condensed (BEC) gas in a racetrack atom-circuit potential. The BEC is confined into a thin horizontal sheet by laser light. The racetrack potential is a channel having two straight channels connected by circular endcaps. The system is assumed to follow the Gross-Pitaevskii model. Flow is produced by stirring the BEC with a rectangular barrier. We have studied in-depth how flow is produced by this stirring. As the barrier strength increases, a backflow develops in the barrier region producing a vortex/anti-vortex pair. The outside vortex circulates like the stir. Above a critical barrier height, the vortices swap places. This generates two disturbances: (1) the vortex/antivortex pair moves off in the anti-stir direction and (2) a compression wave moving the other way. This repeats until the flow produced overtakes the barrier speed. Each new unit of flow creates another pair of disturbances. These disturbances convert the localized circulation of the vortices into macroscopic flow around the racetrack. The flow oscillates around this value until the barrier falls below the critical value determining the final flow. |
Wednesday, March 4, 2020 3:18PM - 3:30PM |
P01.00005: Phase-sensitive amplification and SU(1,1) interferometry via multimode four-wave mixing Erin Knutson, J. Sam Cross, Sara Wyllie, Ryan T Glasser We demonstrate a useful phase dependence in a multi-pump four-wave mixing configuration. We find that, for certain phase values, the intensity noise of an output mode is lower than that of its phase-insensitive counterpart. This lower-noise amplification has been demonstrated previously in atomic four wave mixing, but only with the use of significantly more complex experimental configurations, e.g. dual homodyne detection or cascaded vapor cells. Additionally, our method naturally results in four beams that can be quantum correlated with one another. |
Wednesday, March 4, 2020 3:30PM - 3:42PM |
P01.00006: Search for non-Newtonian gravity with optically-levitated microspheres Charles P Blakemore, Alexander Fieguth, Akio Kawasaki, Denzal Martin, Nadav Priel, Alexander D Rider, Giorgio Gratta The universal law of gravity has undergone stringent tests for a long time over a significant |
Wednesday, March 4, 2020 3:42PM - 3:54PM |
P01.00007: Ultrasensitive torque detection and ultrafast rotation with an optically levitated nanoparticle Jonghoon Ahn, Zhujing Xu, Jaehoon Bang, Peng Ju, Xingyu Gao, Tongcang Li Torque sensors have enabled great accomplishments in physics including the discovery of Coulomb’s law and Cavendish’s first determination of the gravitational constant, and is widely used for studies such as small-scale magnetism and the Casimir effect. Here, we develop an ultrasensitive torque sensor with an optically levitated nanoparticle in vacuum and experimentally demonstrate a torque sensitivity of (4.2 ± 1.2) × 10-27 Nm / sqrt(Hz) at room temperature [1] without the need of comlex nanofabrication or cryogenic cooling. With the optically levitated particles, we are also able to achieve a record high mechanical rotation exceeding 5 GHz [1,2]. Our calculations suggest our torque sensor will allow detection of vacuum friction near a surface under realistic conditions. |
Wednesday, March 4, 2020 3:54PM - 4:06PM |
P01.00008: Towards mass sensing using cavity optomechanics readout Ewa Rej, Mert Yuksel, Warren Fon, Matthew Matheny, Michael Roukes The minute size of nanoelectromechanical systems (NEMS), combined with their large quality factors, has provided a large class of sensors capable of measuring the properties of single molecules. In particular, NEMS have allowed the mass of individual adsorbed molecules, such as protein complexes, to be measured. I will present results showing NEMS based mass spectrometry of individual proteins and explain how the mass resolution is governed by the phase noise of the system, with contributions from the resonator itself, readout circuitry and thermomechanical noise. I will outline our new approach based on a superconducting cavity optomechanics readout scheme for improved sensor performance. The transduction by cavity optomechanics is expected to greatly reduce system phase noise as readout-self heating is minimal. This will directly yield improved resolution in detecting the spatial mass distribution of individual analytes. |
Wednesday, March 4, 2020 4:06PM - 4:18PM |
P01.00009: Searching for scalar dark matter with compact mechanical resonators Jack Manley, Russell Stump, Dalziel Wilson, Daniel Grin, Swati Singh We discuss the viability of laboratory-scale mechanical resonators as detectors for ultralight scalar dark matter. The signal we investigate is an atomic strain due to modulation of the fine structure constant and the lepton mass at the Compton frequency of dark matter particles. The resulting stress can drive an elastic body with breathing modes, producing displacements that are accessible with opto- or electromechanical readout techniques. To address the unknown mass of dark matter particles (which determines their Compton frequency), we consider various resonator designs operating at kHz to MHz frequencies, corresponding to 10-12-10-5 eV particle mass. Current resonant-mass gravitational wave detectors that have been repurposed as dark matter detectors weigh ~103 kg. We find that a large unexplored parameter space can be accessed with ultra-high-Q, cryogenically-cooled, cm-scale mechanical resonators possessing ~107 times smaller mass[1]. |
Wednesday, March 4, 2020 4:18PM - 4:30PM |
P01.00010: Realization of a second-generation scheme for dissipative entanglement of hyperfine beryllium-ion qubits Daniel Cole, Stephen D Erickson, Karl Horn, Florentin Reiter, Panyu Hou, Jenny Wu, Christiane Koch, Andrew C Wilson, Dietrich Leibfried The generation of entanglement using engineered dissipation has recently attracted attention because this approach can be competitive in fidelity and robustness against noise when compared with methods of entanglement generation based on controlled unitary evolution, and can enable optical pumping directly into entangled resource states for quantum protocols [1]. In a dissipative entanglement generation scheme, population is trapped in a target entangled state through evolution according to dissipative dynamics that have the target state as a steady state. We will discuss the generation of entangled states of hyperfine beryllium-ion qubits using engineered dissipation. In particular, we will present experimental realization of a ‘second generation’ scheme for dissipative production of an entangled singlet state that offers an improvement in speed and fidelity, along with reduced experimental complexity [2]. This scheme involves engineering suitable spin-motion couplings in the Hamiltonian, which are then combined with dissipation in the form of pumping to and decay from an electronic excited state. |
Wednesday, March 4, 2020 4:30PM - 4:42PM |
P01.00011: Surface-science studies of electric-field noise from ion-trap electrodes Dustin Hite, Kyle McKay, Phililp Kent, David Pappas Heating of the motional modes of ions in a rf Paul trap is a major obstacle to trapped-ion quantum information processing (QIP). It is caused by electric-field noise from the surface of the trap electrodes, which couples to the ions’ net charge. A better understanding of the physical origin of this surface noise will help to mitigate this heating in trapped-ion QIP applications. To aid in tackling this problem, our group has constructed a one-of-a-kind trapped-ion surface probe, where the ion is used to measure noise from the surfaces of nearby samples positioned into close proximity. This novel surface probe is operated in situ with traditional surface science tools, namely SPM, XPS, and SPA-LEED, where the sample is transferred from instrument to instrument in vacuum. Various treatments to the sample surfaces will elucidate possible origins of the noise. For example, in situ cleaning of the trap electrodes by Ar-ion bombardment reduces this noise by 1 – 2 orders of magnitude. In this talk, I will describe the composition and surface-potential landscape of typical as-fabricated and treated ion-trap electrodes and show results where we have demonstrated the efficacy to use trapped ions as a probe to nearby surfaces. |
Wednesday, March 4, 2020 4:42PM - 4:54PM |
P01.00012: Towards Improved Quantum Simulations and Sensing via Parametric Amplification Matthew Affolter, Elena Jordan, Kevin A. Gilmore, Shaun Burd, John Jacob Bollinger Improving spin coherence is a fundamental challenge in quantum simulations and sensing experiments on trapped ions. Here we discuss preliminary experiments attempting to enhance spin-motion coupling in large ion crystals via parametric amplification without a reduction in the spin coherence. These experiments are performed on 2D crystal arrays of over a hundred Be+ ions confined in a Penning trap. This device has been used to perform quantum simulations and sense displacements of the ion crystal that are small compared to the ground state zero-point fluctuations1. By modulating the trapping potential at twice the center-of-mass mode frequency, we squeeze the motional mode, which can enhance spin-motion coupling while maintaining the spin coherence. This should enable higher fidelity simulations and improve our sensitivity to small displacements. |
Wednesday, March 4, 2020 4:54PM - 5:06PM |
P01.00013: Quantum measurement and many-body dynamics for the Dicke model Yunjin Choi, Shane Kelly, Shan-Wen Tsai The Dicke model (DM) is a well-suited system for exploring enhanced metrology and quantum information processing. An entangled spin-boson cat-state in the DM is obtained when the spin and boson degrees of freedom interact in the strong coupling limit. This entangled spin-boson cat-state is a metrological resource to the spin cat-state in terms of the spin degrees of freedom. However, it is difficult to experimentally explore features of coherence of the entangled spin-boson cat state, and it is hard to control and measure the boson and spin degrees of freedom simultaneously. Treating the spin subsystem as the main system of interest, we consider the bosonic degrees of freedom as an environment that can be controlled and probed to some extent. We investigate a measurement process on the bosonic system to extract partial information about the spin system. The degree to which the spin system is affected by such a measurement can be controlled by the coupling strength between the spin and boson systems. We also discuss the measurement context on the bosonic system to preserve or retrieve coherence of the spin subsystem. |
Wednesday, March 4, 2020 5:06PM - 5:18PM |
P01.00014: Study of the mechanical loss of amorphous mirror coatings for gravitational wave detectors using two level system model Jun Jiang, Alec Mishkin, Kiran Prasai, Riccardo Bassiri, Martin M. Fejer, Hai-Ping Cheng For future generation of laser interferometer gravitational-wave observatory (LIGO), thermal noise from amorphous mirror coatings will be a limiting noise source in the most-sensitive frequency band (about 150 Hz).[CQG 25.11,114041] In our previous studies, two level system (TLS) model was used to study the mechanical loss of the pure and doped amorphous SiO2, Ta2O5 coatings.[JCP 141.5,054501, PRB 93.1,014105, PRB 95.1,014109] With reverse Monte Carlo (RMC) method, we generate amorphous models for both as-deposited and heat treated samples based on measurements of grazing-incidence pair distribution function (GIPDF).[PRL 123.4,045501] In this work, we further refine the RMC models of 50% ZrO2 doped Ta2O5 with first-principles atomic structure relaxation and improve the previous TLS model by correctly taking into account two relaxation times associated with one asymmetrical TLS transition. From the mechanical loss calculation based on these models, we find that annealing will partially eliminate voids (or pores) larger than 200 A3 and smaller than 100 A3 making the atomic structures more uniform, which is correlated with high mechanical loss at low temperature. |
Wednesday, March 4, 2020 5:18PM - 5:30PM |
P01.00015: Atomic Tritium Production and Trapping for Neutrino Mass Measurement in Project 8 Alec Lindman Project 8 is a phased experiment using tritium β decay to investigate the absolute neutrino mass. Good energy precision, high statistics, and well-controlled systematics are required to reach an electron antineutrino mass limit of ≤ 40 meV. Our technique, Cyclotron Radiation Emission Spectroscopy (CRES), has achieved eV-scale resolution at 17.8 keV, near the tritium endpoint. Project 8 was the first to observe the fW-scale radiation from individual electrons. The event rate in CRES scales with volume; we will instrument our fiducial volume with a spatially-resolving antenna array, eliminating pileup. Project 8 will be the first laboratory neutrino mass experiment to use atomic tritium (T). Decay of a T2 molecule excites rovibrational states that smear the observed energy by 1 eV. The decay of T, however, has an energy smearing of ≤ 0.1 eV. Our baseline calls for trapping 30 mK atomic tritium in a 2-T-deep, 10+-m3 superconducting magnetic bottle. I will discuss our approach to this large-volume atomic CRES experiment, focusing on production and handling techniques for recombination-prone tritium atoms. |
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