Bulletin of the American Physical Society
50th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 64, Number 4
Monday–Friday, May 27–31, 2019; Milwaukee, Wisconsin
Session V04: Atomic Clocks and Long-Lived Coherence |
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Chair: Amar Vutha, University of Toronto Room: Wisconsin Center 102AB |
Friday, May 31, 2019 8:00AM - 8:12AM |
V04.00001: Towards accurate predictions of clock transitions in highly charged ions with complex electronic structure Charles Cheung, Marianna Safronova, Sergey Porsev, Mikhail Kozlov, Ilya Tupitsyn Highly charged ions such as Ir$^{17+}$ are attractive candidates for the development of novel atomic clocks with high sensitivity to the variation of the fine-structure constant. The clock transitions are weak and are difficult to identity without accurate theoretical predictions. The cases of Ir$^{16+}$ and Ir$^{17+}$ are particularly difficult due to atomic configurations with holes in the $4f$ shell leading to a very large number of configurations that have to be included within the framework of the configuration interaction (CI) approach. In this work, we developed strategies to identify most important configurations using valence perturbation theory (PT) which can be used to improve and optimize the CI valence space. A parallel version of the code has also been developed, allowing us to perform computations with factor of a 100 larger CI spaces than before within a reasonable computational time. We find that including large number of configurations is necessary for accurate calculations and demonstrate saturation of the CI space for the 15-valent Ir$^{16+}$ and 14-valent Ir$^{17+}$ ions using this method. We calculate low-lying energy levels and transition rates relevant to atomic clock development and compare the results with other values. [Preview Abstract] |
Friday, May 31, 2019 8:12AM - 8:24AM |
V04.00002: Canceling light shifts in two-photon optical clocks using magic polarization Shira Jackson, Amar Vutha Probe laser light shifts represent an important source of uncertainty in optical clocks, especially for clocks operating on highly forbidden transitions or multi-photon transitions. We find magic polarization angles for the probe laser, at which the differential polarizability of the clock states is zero, in calcium and strontium two-photon clocks. Operating the clock at a magic polarization offers a robust and simple way to suppress probe laser light shifts in two-photon clocks. [Preview Abstract] |
Friday, May 31, 2019 8:24AM - 8:36AM |
V04.00003: Isotope shift spectroscopy in neutral strontium Peter Elgee, Neal Pisenti, Hirokazu Miyake, Ananya Sitaram, Nick Mennona, Gretchen Campbell Isotope shift spectroscopy provides a sensitive probe into nuclear physics and recent proposals have suggested using the linearity of King plots to put a bound on new physics. The narrow lines and four stable isotopes of strontium are an attractive platform for such an investigation. We present isotope shift measurements, and a King plot analysis on the $^1$S$_0 \rightarrow ^3$P$_0$ clock transition and the $^1$S$_0 \rightarrow ^3$P$_1$ intercombination line in all four stable isotopes of strontium. This work could help resolve discrepancies between measured and theoretical values for the field shift constants from a similar analysis in Ca$^+$. In addition, it paves the way for using the narrow optical transitions of strontium to put limits on new physics. [Preview Abstract] |
Friday, May 31, 2019 8:36AM - 8:48AM |
V04.00004: Progress of a Cold-Atom CPT Clock based on the Grating Magneto-Optical Trap Rachel Elvin, Gregory W. Hoth, Michael W. Wright, Ben Lewis, Aidan S. Arnold, Paul F. Griffin, Erling Riis We present an experiment that aims to be developed into a portable cold-atom microwave clock. The apparatus is based on a grating magneto-optical trap (GMOT) and the coherent population trapping (CPT) technique, enabling future operation outside of the laboratory environment. The GMOT provides a relatively simple source of cold atomic vapour with good optical access. From one cooling beam incident on a 20 x 20 mm chip made up of three micro-fabricated linear gratings, we can trap and cool $\sim10^{7}$ $^{87}$Rb atoms to $<30~\mu$K when operating the experiment as a clock. We realise our clock signal by adopting CPT in a high-contrast scheme referred to as Lin$\perp$Lin, and by measuring the transmission of the laser probe through the cold atom cloud. A pulsed Raman-Ramsey sequence is implemented to allow for long free evolution times and narrow Ramsey-CPT fringes, whilst also mitigating light-shifts picked up from the interrogation. Here, we will discuss on our efforts in optimising the signal-noise ratio of the Ramsey fringes, characterisation of the detection system as well as some of the systematic shifts we have observed. We report on a signal-noise ratio of approximately 50 and a short-term frequency stability with an Allan deviation of $3\times10^{-11}/\sqrt{\tau}$. [Preview Abstract] |
Friday, May 31, 2019 8:48AM - 9:00AM |
V04.00005: The Optical Rubidium Atomic Frequency Standard: Toward a Rugged Optical Atomic Clock Benjamin Stuhl Ruggedized atomic clocks are necessary for a wide array of applications (e.g., satellite-based navigation and communication). Building upon existing vapor-cell and laser technologies, we describe an optical atomic clock, designed around a simple and manufacturable architecture, that utilizes the 778 nm two-photon transition in rubidium and yields fractional-frequency instabilities of $4 \times 10^{-13} / \sqrt{\tau}$ for $\tau$ from 1 to 10,000 s. We present a stability budget and demonstrate a system design for achieving a fractional-frequency instability of $1 \times 10^{-15}$ that can be maintained on long time scales. [Preview Abstract] |
Friday, May 31, 2019 9:00AM - 9:12AM |
V04.00006: ABSTRACT WITHDRAWN |
Friday, May 31, 2019 9:12AM - 9:24AM |
V04.00007: Interorbital interactions in Ytterbium-171 Oscar Bettermann, Nelson Darkwah Oppong, Giulio Pasqualetti, Luis Riegger, Immanuel Bloch, Simon Foelling Being an alkaline-earth-like atom, Ytterbium features a metastable state, the so-called clock state. This, in conjunction with state-dependent lattices, is a key feature for the realization of two-orbital Hamiltonians such as Kondo-type systems. In our experiment, we investigate the interorbital scattering properties of Ytterbium-171 atoms using clock-line spectroscopy, as well as the lifetime of the interacting states in a three-dimensional optical lattice. For this isotope, we find the interorbital spin-exchange interaction to be antiferromagnetic. We also observe long lifetimes of the interacting states in the lattice, which should be a good starting point for many-body physics with these atoms. This finding complements the known ferromagnetic exchange in Ytterbium-173, which should make both types of spin-exchange interactions available for two-orbital magnetic hamiltonians such as the Kondo model or the Kondo lattice model. [Preview Abstract] |
Friday, May 31, 2019 9:24AM - 9:36AM |
V04.00008: NMR spectroscopy using a solid-state spin sensor with enhanced sensitivity Nithya Arunkumar, Dominik Bucher, David Glenn, Mark Ku, Ronald Walsworth NMR spectroscopy using nitrogen-vacancy (NV) centers is a promising tool for chemical analysis and molecular structure identification, where weak magnetic fields produced by the nuclear spins of the sample are optically measured by the electron spins of the NV center. Conventional, inductively detected NMR can also provide the high spectral resolution, but suffers from poor molecule-number sensitivity and requires millimeter-scale samples. However, NV-NMR spectrometers can observe magnetic signals from sample volumes several orders of magnitude smaller than the most sensitive inductive detectors. But the performance of this ensemble NV magnetometer is limited by the sensitivity of the device. We present a measurement technique to perform high-resolution micron scale NV-NMR spectroscopy with improved sensitivity. We also investigate the influence of the magnetic field and laser power on this measurement technique. [Preview Abstract] |
Friday, May 31, 2019 9:36AM - 9:48AM |
V04.00009: Enhanced spin coherence of rubidium atoms in solid parahydrogen Sunil Upadhyay, Ugne Dargyte, Robert Prater, Vsevolod Dergachev, Sergey Varganov, Timur Tscherbul, David Patterson, Jonathan Weinstein Alkali atoms trapped in solid parahydrogen are optically addressable and have excellent spin coherence properties. They retain these properties at high spin densities, making them a promising platform for applications such as atomic magnetometry in the solid phase. We have identified the physical mechanism that limits the ensemble T$_2^*$ as electrostatic in nature, and are able to achieve significantly longer T$_2^*$ times by using nonclassical spin superposition states. By contrast, we find the spin-echo T$_2$ is limited by interactions that are magnetic in nature. Progress towards identifying the source of this magnetic decoherence will be discussed. [Preview Abstract] |
Friday, May 31, 2019 9:48AM - 10:00AM |
V04.00010: Record long term stability of an optical local oscillator William Milner, Eric Oelker, John Robinson, Colin Kennedy, Tobias Bothwell, Dhruv Kedar, Jun Ye The long term stability of optical local oscillators is of wide scientific interest, from studies of dark matter to applications in time scales. We report on an optical local oscillator based on a cryogenic silicon cavity with improved frequency noise compared with state-of-the-art microwave oscillators at all averaging times up to 5 days. To evaluate the long term stability of our 124 K silicon cavity, a data campaign of over one month was undertaken, which involved daily measurements (of several hours) of the silicon cavity frequency against a 1D strontium lattice clock with systematic uncertainty at the low $10^{-18} $ level. We will present the measurement results and analysis. [Preview Abstract] |
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