Bulletin of the American Physical Society
48th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 62, Number 8
Monday–Friday, June 5–9, 2017; Sacramento, California
Session H3: Atomic and Nuclear Measurements in Ion TrapsFocus
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Chair: Thad Walker, University of Wisconsin Room: 308 |
Wednesday, June 7, 2017 10:30AM - 11:00AM |
H3.00001: Precision ion trap measurements in nuclear physics Invited Speaker: Jens Dilling Nuclear Physics is a fundamental science discipline, which started over 100 years ago, and is concerned with the understanding of how nuclear matter is held together in its innermost and how its structures behave and evolve. Recent progress in experimental and theoretical techniques has advanced the field significantly, but some questions remain. Moreover, new nuclear phenomena have been discovered, this includes so-called nuclear halo nuclei and the appearance of different nuclear shells. Ion trap technologies, originally developed for atomic and molecular physics, have been adapted to the specific requirements stemming from nuclear physics, for example, to couple ion traps to accelerators and achieve very high speed and efficiencies. In this talk I will show some examples and technical developments pertaining to nuclear physics questions and phenomena and how they are addressed with precision ion trap measurements. [Preview Abstract] |
Wednesday, June 7, 2017 11:00AM - 11:30AM |
H3.00002: Ultrasensitive magnetometer using a single atom Invited Speaker: Christof Wunderlich Precision sensing, and in particular high precision magnetometry, is a central goal of research into quantum technologies. The precision, and thus the sensitivity of magnetometry scales as $1/\sqrt {T_2}$ with the phase coherence time $T_2$ of the sensing system. Typical quantum sensing protocols prolong $T_2$ of the quantum states used for sensing by using dynamical decoupling (DD), that is, applying a continuous or pulsed electromagnetic driving field. In the case of pulsed DD, the required repetition rate of pulses -- with each pulse having a well defined pulse area -- is proportional to the frequency of the field to be detected with high sensitivity, thus effectively limiting the frequency range of the sensor. To achieve a long coherence time $T_2$ using continuous DD, the amplitude of the driving field has to be kept highly stable for time $T_2$, another technologically challenging problem. Here, we implement a decoupling scheme using two continuous decoupling fields in an atomic 4-level scheme. Thus, the coherence time is no longer limited by fluctuations of the amplitude of the decoupling fields. Instead, $T_2$ is determined by the frequency stability of the driving fields which is straight forward to maintain with high precision using, for instance, a commercial atomic clock. Using a single trapped $^{171}$Yb$^+$ ion as a sensor, we experimentally attain a sensitivity of $4.6$ pT $/\sqrt{\mbox{Hz}}$, to our knowledge the best sensitivity so far realized with a single atom \footnote{I. Baumgart, J.M. Cai, A. Retzker, M.B. Plenio, C. Wunderlich, Phys. Rev. Lett. \textbf{116}, 240801 (2016).}. The detected magnetic field is an alternating-current (AC) magnetic field near 14 MHz. Based on the principle demonstrated here, this unprecedented sensitivity together with its tuneability from direct-current to the gigahertz range could be used for magnetic imaging in as of yet inaccessible parameter regimes. [Preview Abstract] |
Wednesday, June 7, 2017 11:30AM - 11:42AM |
H3.00003: Precision mass ratios of mass-3 ions Edmund G Myers, Saeed Hamzeloui, Jordan R Smith, David J Fink Precision atomic masses of hydrogen, deuterium and helium-3 are important fundamental constants with application to a wide range of physical science. Using a rebuilt and improved Penning trap mass spectrometer, we are measuring the ion mass ratios HD$^{\mathrm{+}}$/H$_{\mathrm{3}}^{\mathrm{+}}$, $^{\mathrm{3}}$He$^{\mathrm{+}}$/H$_{\mathrm{3}}^{\mathrm{+}}$ and $^{\mathrm{3}}$He$^{\mathrm{+}}$/HD$^{\mathrm{+}}$. The results will help resolve the current four-sigma discrepancy for the mass of $^{\mathrm{3}}$He. [Preview Abstract] |
Wednesday, June 7, 2017 11:42AM - 11:54AM |
H3.00004: Reducing time-dilation uncertainty in the NIST Al+ quantum-logic clock Samuel Brewer, Jwo-Sy Chen, Aaron Hankin, Ethan Clements, Chin-wen Chou, David Wineland, David Leibrandt, David Hume Previous optical atomic clocks based on quantum-logic spectroscopy of the $^1S_0$ $\longleftrightarrow$ $^3P_0$ transition in $^{27}$Al$^+$ have reached an uncertainty of $\delta \nu / \nu = 8.0 \times 10^{-18}$ dominated by time-dilation shifts due to driven motion (i.e., micromotion) and thermal (secular) motion of the trapped ions. Excess micromotion is typically the result of imperfections in trap fabrication while the uncertainty in the thermal motion has been limited by difficulties in determining the ion temperature near the Doppler cooling limit. We report on Raman sideband cooling of $^{25}$Mg$^{+}$ to sympathetically cool the secular modes of motion in a $^{25}$Mg$^{+}$-$^{27}$Al$^{+}$ two-ion pair to near the three-dimensional (3D) ground state. We characterize the residual energy and heating rates of all of the secular modes of motion and estimate a secular motion time-dilation shift of $-(1.9 \pm 0.1) \times 10^{-18}$ for an $^{27}$Al$^{+}$ clock at a typical clock probe duration of 150 ms. This is a 50-fold reduction in the secular motion time-dilation shift uncertainty in comparison with previous $^{27}$Al$^{+}$ clocks. Furthermore, we present a preliminary characterization of the micromotion time-dilation shift uncertainty in an improved ion trap. [Preview Abstract] |
Wednesday, June 7, 2017 11:54AM - 12:06PM |
H3.00005: Isotopic shift measurement of Na-like Xe ions as a new method to measure absolute and relative charge radii of rare isotopes. R. Silwal, A. Lapierre, J.D. Gillaspy, A.C.C. Villari, G. Gwinner, S.A. Blundell, B.H. Rudramadevi, A. Borovik, Jr., J.M. Dreiling, Yu. Ralchenko, E. Takacs The absolute charge radius of unstable (radioactive) isotopes is mostly unavailable for elements heavier than Bi as current measurement techniques, e.g. electron scattering and muonic x-ray spectroscopy, require macroscopic amounts of the elements. Relative shifts in charge radii along isotopic chains, obtained from optical frequency shifts, strongly depend on semi-empirical approaches thereby adding further uncertainties. Transition energies of Na-like ions are sensitive to nuclear size, and because of their simple electronic structure, ab-initio atomic structure calculations can reach high accuracy. For heavy elements, it has even been noted that the precision of such calculations is limited by the large uncertainty in charge radii$^{\mathrm{1}}$. This suggests a new method for charge radius measurements using Na-like ions. We have measured energy shifts associated with the D1 and D2 3s-3p transitions for Na-like $^{\mathrm{124}}$Xe and $^{\mathrm{136}}$Xe. The relative shift in charge radius of these isotopes is inferred by comparing experiment and high-precision calculations. We present preliminary results obtained from EUV and x-ray spectra observed in an electron beam ion trap. [1] Gillaspy et al., PRA 87, 062503 (2013). [Preview Abstract] |
Wednesday, June 7, 2017 12:06PM - 12:18PM |
H3.00006: Progress towards a Lutetium-ion optical clock Kyle Arnold, Rattakorn Kaewuam, Arpan Roy, Murray Barrett Recently singly ionized Lutetium has been proposed as a promising ion-clock candidate. It has multiple potential clock transitions from the $^1$S$_0$ ground state to the low-lying meta-stable $D$ states. In particular, it is a potential candidate for realizing multi-ion clock proposals requiring clock transitions with negative differential scalar polarizability. We report recent experimental progress with $^{176}$Lu$^{+}$. The low natural abundance $^{176}$Lu isotope has been isolated by laser photo-ionization and can be now be loaded and cooled without a sympathetic cooling agent. Laser spectroscopy has been performed to measure the frequencies of the allowed dipole transitions and clock transitions relevant for clock operation. In addition, the hyperfine structure of the $^3$P$_1$, $^3D_1$, and $^3D_2$ states has been measured. Progress towards implementation of the hyperfine averaging clock protocol and direct measurement of the differential scalar polarizability of the $^1$S$_0$ to $^3$D$_1$ transition will be presented. [Preview Abstract] |
Wednesday, June 7, 2017 12:18PM - 12:30PM |
H3.00007: An Ultra-Cooled Atomic Quantum Sensor for Precision Detection of Oscillating Electric Signals Daniel Rodriguez, J. Berrocal, F. Dominguez, M. J. Gutierrez, R. Rica Non-destructive detection of oscillating charges with minute strengths is important for several applications, particularly to perform ultra-accurate mass measurements by means of Penning traps. There are remarkable results obtained using electronic circuits [Nature 506, 467 (2014)], when the trapped charged particle is more than 100 times lighter than a superheavy atom. In this contribution, we will report on a novel concept under commissioned at the University of Granada, to replace the circuit immersed in a liquid-helium tank, by a laser-cooled Ca$^+$ ion held in an ion trap with rotational symmetry, that should be coupled to another bound particle, following a previous idea published in the nineties [PRA 42, 2977 (1990)]. So far, we have studied the miliKelvin ion reservoir (after Doppler cooling), theoretically and experimentally, in collaboration with the QUTIS group (E. Solano et al.), to obtain the full characterization [arXiv:1612.08577]. We work currently towards applying ground-state cooling to reach the Quantum-limited region of performance, and in parallel, in the completion of a double micro-Penning trap mass spectrometer for ion-ion coupling, which has been built in collaboration with a group at PTB and Uni. Hannover (C. Ospelkaus et al.) [IJMS 410C, 22 (2016)]. [Preview Abstract] |
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