Bulletin of the American Physical Society
40th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 54, Number 7
Tuesday–Saturday, May 19–23, 2009; Charlottesville, Virginia
Session X4: Precision Measurements |
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Chair: Carol Tanner, University of Notre Dame Room: Clark Hall 108 |
Saturday, May 23, 2009 10:30AM - 10:42AM |
X4.00001: Evidence for Nuclear Magnetic Octupole Moments in 133Cs and 87Rb from Measurements of Hyperfine Intervals Carol E. Tanner, Vladisalv Gerginov, Walter R. Johnson We previously performed high precision measurements of the 133Cs 6p~2P3/2 F=2, 3, 4, 5 hyperfine intervals from which we determined the hyperfine constants A, B, and C corresponding to the magnetic dipole, electric quadrupole, and magnetic octupole moments of the nucleus interacting with the orbital electrons. The existence of a nuclear magnetic octupole moment in Cs was revealed in Gerginov \textit{et al.}, Phys. Rev. Lett. 91, 072501 (2003). These results were later confirmed by our measurements of the absolute optical frequencies of all hyperfine components of the 6s~2S1/2~F=3, 4--$>$6p~2P3/2~F=2, 3, 4, 5 transition, Phys Rev. A 70, 042502 (2004). During our investigations, we discovered existing measurements of the 87Rb 5p~2P3/2 F=0, 1, 2, 3 hyperfine intervals by Ye \textit{et al}., Opt. Lett. 21, 1280 (1996). We decomposed these measurements in terms of the constants A, B, and C and combine this value of C with relativistic MBPT atomic structure calculations to determine the nuclear magnetic octupole moment of 87Rb, Can. J. Phys. 87 (2009). We examined the influence of second order hyperfine corrections for both atoms and found no significant changes in the values of A, B, and C. Since the experimental uncertainties in Rb are relatively large more precise measurements are warranted. [Preview Abstract] |
Saturday, May 23, 2009 10:42AM - 10:54AM |
X4.00002: Atomic mass measurements for neutrino mass Matthew Redshaw, Brianna Mount, Edmund Myers As usually understood, observation of neutrinoless double-beta-decay implies that neutrinos are their own antiparticles (Majorana particles), while measurements of the decay rate, or limits on the rate, provide information on absolute neutrino mass. Large-scale neutrinoless double-beta-decay detectors, proposed or under development, such as EXO, CUORE, GERDA, MAJORANA, etc. should be sensitive to a linear combination of neutrino masses, the ``effective Majorana mass of the electron neutrino'', below 0.1 eV/c$^{2}$. The signature of neutrinoless double-beta decay is a sharp peak in the total electron-energy spectrum at the Q-value of the decay -- the mass-energy difference between the parent and daughter atoms. Using one or two multiply-charged ions in a Penning trap, we have now measured the atomic masses of $^{136}$Xe, $^{130}$Te, $^{130}$Xe, $^{76}$Ge, $^{76}$Se to a fractional precision of 2 x 10$^{-10}$ or better, corresponding to Q-values with uncertainties below 25 eV. This is more than sufficient precision for the proposed large-scale experiments. Progress on mass measurements of $^{74}$Ge and $^{74}$Se, relevant to resonance-enhanced neutrinoless double-electron capture in $^{74}$Se, will also be reported. [Preview Abstract] |
Saturday, May 23, 2009 10:54AM - 11:06AM |
X4.00003: Atomic masses of the alkalis, oxygen isotopes, and the dipole of a triatomic ion Brianna Mount, Matthew Redshaw, Edmund Myers By measuring cyclotron frequency ratios of multiply charged ions simultaneously trapped in a Penning trap we have obtained improved atomic masses for $^{39,41}$K, $^{85,87}$Rb and $^{133}$Cs. Our results for Rb and Cs have application to ongoing measurements of h/m(alkali) for the finestructure constant. We have also measured the masses of $^{17,18}$O, with application to an isotope-independent global fit of precision ro-vibrational molecular spectroscopic data of carbon monoxide [1]. By measuring cyclotron frequency shifts due to polarizability, we have also measured the dipole moment of the triatomic molecular ion HCO$^{+}$. [1] H.S.P Mueller, et al., unpublished. [Preview Abstract] |
Saturday, May 23, 2009 11:06AM - 11:18AM |
X4.00004: Limit on variation of fundamental constants from photoassociation in ultracold gases Marko Gacesa, Robin C\^ot\'e We propose a novel approach to measure the limit on the time variation of the electron-to-proton mass ratio $\beta=m_e/m_p$. It has been shown that the scattering length, which can be obtained from ultracold scattering experiments, is extremely sensitive to $\beta$ \footnote{Cheng Chin and V. V. Flambaum, PRL 96, 230801(2006)}. We show that the photoassociation (PA) rate of ultracold atoms into molecules can also exhibit such dependence. The PA rate near a Feshbach resonance, which exhibits both a maximum at the resonance and a minimum in vicinity, allows for high sensitivity at both, while near the minimum the saturation effect is negligible. Our prediction based on a two-channel model and numerical solution indicates that the precision measurement of variation of $\beta$ of up to $10^{-14}-10^{-15}$ could be possible in a suitable system. [Preview Abstract] |
Saturday, May 23, 2009 11:18AM - 11:30AM |
X4.00005: Probing Interactions Between Ultracold Fermions Gretchen Campbell, Andrew Ludlow, Jan Thomsen, Martin Boyd, Michael Martin, Sebastian Blatt, Matthew Swallows, Travis Nicholson, Jun Ye At ultracold temperatures, the Pauli exclusion principle suppresses collisions between identical fermions. This has been a strong motivation for the development of optical atomic clocks using fermionic isotopes. However, using a $^{87}$Sr optical lattice clock we recently measured density-dependent frequency shifts of the clock transition. A systematic study of these collision effects has been completed and we have developed a theoretical model which provides a fundamental description of fermionic interactions including the effect of the measurement process on the dynamic evolution of the two particle correlation function. Importantly, for clock operations we have also identified experimental conditions that allow this density shift to be zeroed out. [Preview Abstract] |
Saturday, May 23, 2009 11:30AM - 11:42AM |
X4.00006: Compact atomic clock prototype using a Rb vapor cell and a vertical cavity surface emitting laser Eugeniy Mikhailov, Nathan Belcher, Irina Novikova Development of compact power efficient atomic clock is a crucial step to improve consumers navigation systems. Low-threshold vertical cavity surface emitting lasers (VCSEL) generate a single spatial mode and can be modulated at very high RF frequencies, making them ideal light sourse for atomic clocks based on electromagnetically induced transparency (EIT) and other coherent effects in atoms. However, large phase noise (in the order of several hundreds megahertz) of a typical VCSEL couples into the atomic medium and degrades short term stability of an atomic clock. We discuss the optimal power regime to minimize this effect as well as other ways to improve long term stability of the clocks. [Preview Abstract] |
Saturday, May 23, 2009 11:42AM - 11:54AM |
X4.00007: Calculation of Blackbody Radiation Shifts for Atomic Clock Research Marianna Safronova, M.G. Kozlov, Dansha Jiang, Bindiya Arora, Charles W. Clark, Ulyana Safronova A systematic study of the black-body radiation (BBR) shifts in various systems of interest to the development of optical frequency standards is carried out. The calculations for monovalent systems, such as Ca$^{+}$ and Sr$^{+}$, are carried out using the relativistic all-order method where all single and double excitations of the Dirac-Fock wave function are included to all orders of perturbation theory. This method was demonstrated to yield accurate predictions for various atomic properties of monovalent atoms. Precision calculations for atoms with more than one valence electron require an accurate treatment of the very strong valence-valence correlation; a perturbative approach leads to significant difficulties. Our calculations of BBR shifts for divalent systems such as Sr are carried out using a new approach that combines the relativistic all-order method and the configuration-interaction method. Other atomic properties of monovalent and divalent systems of interest to atomic clock research are evaluated as well. The shift due to blackbody radiation in the hyperfine transition (F=1, M=0 -- F=0, M=0) in $^{171}$Yb$^{+}$ is also evaluated and found to be in good agreement with the only existing calculation of Angstmann et al. [Phys. Rev. A \textbf{74}, 023405 (2006)]. [Preview Abstract] |
Saturday, May 23, 2009 11:54AM - 12:06PM |
X4.00008: Third-order relativistic many-body calculations of energies, transition rates, hyperfine constants, and black-body radiation shift in $^{171}$Yb$^+$ Ulyana Safronova, Marianna Safronova Relativistic many-body perturbation theory is applied to study properties of singly ionized ytterbium, Yb$^+$. Specifically, energies of the [Xe]$4f^{14}ns_{1/2}$, [Xe]$4f^{14}np_j$, and [Xe]$4f^{14}nd_j$ ($n \leq$9) are calculated through third order. Reduced matrix elements, oscillator strengths, and transition rates are determined for electric-dipole transitions including the $6s$, $7s$, $8s$, $6p$, $7p$, $5d$ and $6d$ states. Lifetime values are determined for the $6p$ states. Electric-dipole ($6s_{1/2}\ -np_j$, $n$ = 6--12) matrix elements are calculated to obtain the ground state E1 polarisabilitie. The hyperfine $A$-values are determined for the low-lying levels up to $n = 7$ of $^{171}$Yb~II. The quadratic Stark effect on hyperfine structure levels of $^{171}$Yb~II ground state is investigated. The calculated shift for the ($F$ = 1, $M$ =0) $\leftrightarrow$ ($F$ = 0, $M$ =0) transition is -0.1796~Hz/(kV/cm)$^2$, in agreement with previous theoretical result -0.171$\pm$0.009. These calculations provide a theoretical benchmark for comparison with experiment and theory. [Preview Abstract] |
Saturday, May 23, 2009 12:06PM - 12:18PM |
X4.00009: Precise measurement of the hyperfine splittings within the 6p$_{3/2}$ level of atomic indium using two-color diode laser spectroscopy. Mevan Gunawardena, Huajie Cao, Paul W. Hess, P.K. Majumder The hyperfine splittings of the 6P$_{3/2 }$state of indium(I=9/2) have been measured for the first time using a two-step, two-color excitation scheme. These results provide a precise experimental test of new \textit{ab initio} wavefunction calculations of three-valence-electron atomic systems such as indium and thallium. We first excite ground-state atoms in a heated quartz indium cell to the intermediate 6S$_{1/2}$ state using a blue (GaN) diode laser at 410 nm. By measuring the differential atomic vapor cell absorption of double-passed, second-order-diffracted beams from an acousto-optic modulator, we are able to stabilize the blue laser frequency to the sub-MHz level [M. Gunawardena et al., Rev. Sci. Instrum. 79. 103110 (2008)]. A second laser beam at 1291 nm overlaps the first in the vapor cell, exciting Doppler-narrowed hyperfine transitions to the 6P$_{3/2}$ excited state. By modulating the blue laser beam and using lock-in detection, we obtain background-free and Dopper-free IR spectra. By locking first to one then the other intermediate hyperfine level, we determine all three hyperfine splittings, as well as the A, B, and C hyperfine constants, for the 6P$_{3/2}$ excited state. Our experimental value for the `A' hyperfine constant agrees with the published theoretical value to within 2{\%}. Details of the measurement and analysis will be presented. [Preview Abstract] |
Saturday, May 23, 2009 12:18PM - 12:30PM |
X4.00010: Doppler-free two-photon spectroscopy of Cs $6S_{1/2}$-$7D_{3/2,\,5/2}$ transition Chin-Chun Tsai, Yi-Hsiu Chang, Ying-Yu Chen, Yi-Chih Lee, Hsiang-Chen Chui High-Resolution Doppler-free two-photon spectra of the $|6S_{1/2},F\rangle-|7D_{3/2,5/2},F\rangle$, transition in cesium are observed using a Ti-Sapphire laser. A repeat two- photon spectrum is used as a frequency maker with signals recorded from the zero- and first-order laser beams generated by an acousto-optic modulator. The hyperfine coupling constants A (magnetic dipole constant) and B (electric quadrupole constant) are determined using spectral line splittings, giving $A=7.12(07)\,MHz$, and $B=0.29(89)\,MHz$ for the $7D_{3/2}$ level, and $A=-1.57(13)\,MHz$, and $B=-0.54(64)\,MHz$ for the $7D_{5/2}$ level. To authors knowledge, these hyperfine two- photon transitions have been observed for the first time. These spectra can be used as an optical frequency standard in the near-infrared region of 767\,nm. [Preview Abstract] |
Saturday, May 23, 2009 12:30PM - 12:42PM |
X4.00011: Spectroscopy of a singly trapped $^{25}$Mg$^{+}$ ion Jason Nguyen, Brian King We will present and discuss results from a measurement of the linewidth and hyperfine A constant of the $^{2}$P$_{1/2}$ excited state in $^{25}$Mg$^{+}$.\space We trapped the ion in a linear Paul trap and laser cooled it using the $^{2}$S$_{1/2}$ $\rightarrow$ $^{2}$P$_{3/2}$ transition.\space We optically pumped the ion into the F=3, m$_{F}$=-3 ground state and weakly probed it with a tuneable fiber laser that was scanned to drive the ion from the ground state to the F=3 and F=2 manifolds of the $^{2}$P$_{1/2}$ state. The final state of the ion was determined by by counting fluorescence (or the lackthereof) from the $^{2}$S$_{1/2}$(F=3,m$_{F}$=-3) $\rightarrow$ $^{2}$P$_{3/2}$(F=4,m$_{F}$=-4) cycling transition with a photomultiplier tube.\space Using this method we measured the linewidth with negligible Doppler contributions at different laser intensities and varying magnetic fields. [Preview Abstract] |
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