Bulletin of the American Physical Society
38th Annual Meeting of the Division of Atomic, Molecular, and Optical Physics
Volume 52, Number 7
Tuesday–Saturday, June 5–9, 2007; Calgary, Alberta, Canada
Session B5: Metrology & Electric Dipole Moments |
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Chair: D. Durfee, Brigham Young University Room: TELUS Convention Centre Glen 205 |
Wednesday, June 6, 2007 10:30AM - 10:42AM |
B5.00001: Slow-Atom Electron EDM Experiment with Electric Field Quantization Harvey Gould, Jason Amini, Charles Munger Jr. Improving the electron electric dipole moment (e-EDM) upper limit has been a 40-year battle against systematic effects. Two new weapons in this battle are slow atoms and ground-state electric field quantization, both of which suppress motional magnetic field effects. They have been used effectively in a recently completed e-EDM experiment that is a prototype for a high-sensitivity Cs fountain e-EDM experiment. Electric field quantization of Cs atoms required nulling residual magnetic fields to $<$ 200 pT, transport of polarized atoms through field-free (nulled) regions, and inducing transitions between closely spaced $|m_F|$ levels using separated short pulses in place of oscillatory fields. The possibility of improving the e-EDM limit with a Cs fountain experiment will be discussed. [Preview Abstract] |
Wednesday, June 6, 2007 10:42AM - 10:54AM |
B5.00002: An Electron EDM Search Using Trapped Molecular Ions Laura Sinclair, John Bohn, Aaron Leanhardt, Edmund Meyer, Russell Stutz, Eric Cornell A sample of trapped molecular ions offers unique possibilities to search for a permanent electron electric dipole moment (EDM). Specifically, we plan to perform this search using the unpaired electron spins in the $^3\Delta_1$ state of trapped HfF$^+$ molecular ions. Ions are easy to trap which will provide the long coherence times necessary to measure the small energy differences associated with an electron EDM. Additionally, the internal electric fields in polarized diatomic molecules can exceed $10^{10}$~V/cm, which will amplify any EDM induced energy splittings. We have created HfF$^+$ ions in a supersonic expansion jet by ablating a Hf target with a pulsed Nd:YAG laser in a He + 1\%SF$_6$ environment. The chemical reaction $\rm{Hf}^+ + \rm{SF}_6 \longrightarrow \rm{HfF}^+ + \rm{SF}_5$ is exothermic and proceeds rapidly. The He buffer gas in the expansion cools the molecular translational, vibrational, and rotational degrees of freedom to $\sim 10$~K. We have measured these temperatures via laser induced fluorescence spectroscopy on known neutral Hf atomic lines and newly identified neutral HfF molecular lines, and are currently searching for the unknown HfF$^+$ electronic transitions. [Preview Abstract] |
Wednesday, June 6, 2007 10:54AM - 11:06AM |
B5.00003: Progress Towards a New Measurement of the Electric Dipole Moment of $^{199}$Hg. M.D. Swallows, W.C. Griffith, B.R. Heckel, E.N. Fortson, M.V. Romalis We are currently undertaking a four vapor cell search for the permanent electric dipole moment (EDM) of $^{199}$Hg. The existence of a nonzero EDM would imply a source of CP violation beyond the standard model. The present limit on the EDM of $^{199} $Hg is $\left|d_{\mathrm{Hg}}\right| < 2.1 \times 10^{-28} \,e\,{\rm cm}$, which was established several years ago by our group at the University of Washington. In that experiment, two quartz vapor cells containing polarized Hg vapor were placed in parallel magnetic and anti-parallel electric fields (the use of two cells permitted the removal of common-mode effects), and the spin precession frequency was measured using an optical technique. In our current experiment, two additional cells at zero electric field serve to cancel magnetic gradient noise and to improve limits on systematic effects due to charging and leakage currents. We have recently overcome several systematic issues and begun acquiring data with our upgraded apparatus. To prevent experimenter bias from influencing the data, we have also instituted a blind analysis protocol. The statistical error of the data at the time of this writing was $\pm0.15\times10^{-28}\ e\ \mathrm{cm}$, and we hope to improve the sensitivity by a further factor of two. We will discuss recent progress and our plans to place improved limits on systematic effects. [Preview Abstract] |
Wednesday, June 6, 2007 11:06AM - 11:18AM |
B5.00004: Toward Searches for Electric Dipole Moments of Radium Subhadeep De, Umakanth Dammalapati, Klaus Jungmann, Aran Mol, Lorenz Willmann Within the TRI$\mu$P (\textbf{T}rapped \textbf{R}adioactive isotopes \textbf{$\mu$}icro - laboratories for fundamental \textbf{P}hysics) programme we are performing experiments searching for violation of discrete symmetries (\textbf{P}arity (\textbf{P}), \textbf{T}ime reversal (\textbf{T}) and \textbf{C}harge conjugation (\textbf{C})) in fundamental interactions. This allows to test various possible extensions to the standard model of the electro-weak interactions. In particular we are searching permanent electric dipole moment (edm) which violates both P and T. The radium (Ra) isotope ($^{213}Ra$) offers several orders of magnitude ($\cong10^4$) enhancement of an edm signal compare to any other system due to their atomic structure [1]. Laser cooling and trapping is an essential tool to increase sensitivity of such an experiment. Possible laser cooling schemes for radium involve leaky cooling transitions. Magneto optical trapping of atoms with a leaky transition requires improvement of the known cooling techniques. As an example we demonstrate laser cooling of barium. We successfully slowed barium atoms from a thermal atomic beam. \begin{description} \item{[1]} V. A. Dzuba et al., PRA 61, 062509, (2000) \end{description} [Preview Abstract] |
Wednesday, June 6, 2007 11:18AM - 11:30AM |
B5.00005: Accurate determination of the electric-dipole matrix elements in K and Rb from the Stark shift measurements Marianna Safronova, Bindiya Arora, Charles W. Clark Stark shifts of the rubidium and potassium D1 lines have been measured with high precision by Miller {\it et al} [1]. In this work, we combine these measurements with our all-order calculations to determine the values of the electric-dipole matrix elements for the $4p_{j}-3d_{j^{\prime}}$ transitions in K and for the $5p_{j}-4d_{j^{\prime}}$ transitions in Rb to high precision. These transitions contribute on the order of 90\% to the respective polarizabilities of the $np_{1/2}$ states in K and Rb, and the remaining 10\% can be accurately calculated using the relativistic all-order method. Therefore, the combination of the experimental data and theoretical calculations allows to determine the $np-(n-1)d$ matrix elements and their uncertainties. We also compare these values with our all-order calculations for a benchmark test of the accuracy of the all-order method for transitions involving $nd$ states. Such matrix elements are of special interest for many applications, such as determination of the ``magic'' wavelengths in alkali-metal atoms for state- insensitive cooling and trapping and determination of blackbody radiation shifts in optical frequency standards with ions. \\ \noindent [1] K.\ E.\ Miller and D.\ Krause and L.\ R.\ Hunter, Phys.\ Rev.\ A 49, 5128 (1994) [Preview Abstract] |
Wednesday, June 6, 2007 11:30AM - 11:42AM |
B5.00006: State-selective ionization of lead monofluoride C.P. McRaven, P. Sivakumar, N.E. Shafer-Ray Lead monofluoride is an important molecule in the search for the electron electric dipole moment. We have developed a doubly resonant photoionization scheme for complete rotational state sensitivity of the ground state. Experimental details and spectroscopic constants are presented. [Preview Abstract] |
Wednesday, June 6, 2007 11:42AM - 11:54AM |
B5.00007: Precision Mass Spectrometry and Polarizability Shifts with Two Ions in a Penning Trap Matthew Redshaw, Joseph McDaniel, Elizabeth Wingfield, Brianna Mount, Edmund Myers We have implemented a technique for precision mass spectrometry with two ions simultaneously confined in a Penning trap in which each ion is alternately positioned at the center of the trap - where the cyclotron frequency is measured - or else parked in a large cyclotron orbit [1]. We have resolved previous systematics and have been able to exploit the improved statistical precision available with this technique. We have now used this technique to measure the mass ratios $^{31}$P$^{+}$/$^{28}$SiH$_{3}$$^{+}$, $^{28}$Si$^{+}$/ $^{13}$C$_{2}$H$_{2}$$^{+}$ and $^{28}$Si$^{+}$/$^{12}$C$_{2}$H$_{4}$$^{+}$ to obtain new values for the atomic mass of $^{28}$Si and $^{31}$P. In addition we have studied the ratio $^{31}$PH$^{+}$/$^{16}$O$_{2}$$^{+}$ to measure shifts in the cyclotron frequency of $^{31}$PH$^{+}$ due to the interaction between the ion's polarizability and the motional electric field. This has led to a measurement of the polarizability and dipole moment of $^{31}$PH$^{+}$. [1] M. Redshaw, J. McDaniel, W. Shi and E. G. Myers, Int. J. Mass Spec. \bf251\rm, 125 (2006). [Preview Abstract] |
Wednesday, June 6, 2007 11:54AM - 12:06PM |
B5.00008: Blackbody radiation shift in optical frequency standard with $^{43}$Ca$^{\rm{+}}$ ion Bindiya Arora, M.S. Safronova, Charles W. Clark The static polarizabilities of Ca$^+$ ion in the $4s_{1/2}$ ground and $3d_{5/2}$ excited states are calculated to high precision. The calculations are based on the relativistic all-order single-double method where all single and double excitations of the Dirac-Hartree-Fock wave function are included to all orders of perturbation theory. The accuracy of the all-order electric-dipole matrix elements for the $4s-np_{1/2}$, $4s-np_{3/2}$, $3d_{5/2}-np_{3/2}$, $3d_{5/2}-nf_{5/2}$, and $3d_{5/2}-nf_{7/2}$ transitions needed for the polarizability calculations is investigated. Additional calculations are conducted for the dominant contributions in order to evaluate some omitted high-order corrections and evaluate the resulting uncertainties in the polarizability values. We use the the polarizability values to calculate the black body radiation shift in $4s_{1/2}-3d_{5/2}$ transition of Ca$^{\rm{+}}$ ion at room temperature (T=300 K) and its uncertainty. The tensor polarizability of the $3d_{5/2}$ level is also calculated and its uncertainty is evaluated as well. Our results are compared with other calculations. This work is motivated by a prospect of optical frequency standard based on a $^{43}$Ca$^+$ ion. [Preview Abstract] |
Wednesday, June 6, 2007 12:06PM - 12:18PM |
B5.00009: A Thermal-beam Calcium Interferometer Christopher Erickson, Marshall Van Zjill, Matthew Washburn, James Archibald, Dan Christensen, Jeremiah Birrell, Adam Burdett, Dallin Durfee We report on the construction of a next-generation atom interferometer. Our research includes developing passive stabilization techniques, low-noise laser current drivers, high-speed scan-balancing lock circuits, and high-speed low-noise photo-detecting units. Our efforts have lead to developing an extremely stable laser locked to an ultra-high finesse optical cavity for use in a Ramsey-Bord\a'e interferometer scheme. The interferometer itself is based on a thermal calcium beam and will be upgraded in the future to a dual species Ca/Sr interferometer sensitive enough to improve measurements of possible time variance of the fine structure constant. [Preview Abstract] |
Wednesday, June 6, 2007 12:18PM - 12:30PM |
B5.00010: New search for a spin-gravity interaction Derek Kimball We are beginning an experiment to search for a new long-range coupling between nuclear spins and the mass of the Earth. If interpreted as a limit on a spin-gravity interaction of the form \textbf{S$\cdot $g} between nuclear spins \textbf{S} and the gravitational field of the Earth \textbf{g}, the experiment would improve present experimental limits by over two orders of magnitude. The presence of such an interaction would be evidence that gravity violated parity and time-reversal symmetries to a small degree, as well as being a breakdown of the equivalence principle which underlies the theory of general relativity. The experiment would set new experimental limits on hypothetical scalar and vector components of gravitational fields. This new experimental search is motivated by recently developed techniques in the field of atomic magnetometry enabling significant improvement in sensitivity to atomic spin precession. The experiment will use nonlinear optical rotation of near-resonant laser light to measure the spin-precession frequency of alkali atoms in the presence of a magnetic field \textbf{B}. The difference between the precession frequencies for the two different ground state hyperfine levels yields a signal proportional only to anomalous interactions that do not scale with the magnetic moments of the atoms. The sum of the precession frequencies enables ultra-precise determination of \textbf{B} to correct for associated systematic errors. [Preview Abstract] |
Wednesday, June 6, 2007 12:30PM - 12:42PM |
B5.00011: Near-IR frequency comb to characterize acetylene-filled fiber-based frequency references Kristan L. Corwin, Rajesh Thapa, Kevin Knabe, Karl Tillman, Andrew Jones, Brian R. Washburn, Jeffrey W. Nicholson, Man F. Yan Optical frequency combs have revolutionized the field of optical frequency metrology. Typically Ti:sapphire lasers form the basis of these combs, but Cr:forsterite offers an interesting alternative in the near-IR, lasing at $\sim $1250 nm, and broadened in a highly nonlinear fiber (HNLF) to span an octave between 1020 and 2040 nm. We have demonstrated the first self-referenced Cr:forsterite laser that uses prisms for dispersion compensation, and observe narrower carrier-envelope offset beatnotes than in the case of the first Cr:forsterite laser to be self-referenced [1]. We will use this comb to characterize optical frequency references based on acetylene-filled hollow photonic bandgap optical fibers. Furthermore, we have developed a simplified technique for observing sub-Doppler features in these fibers, called a ``reflected pump'' technique, and compare it to more conventional methods. [1] K. Kim \textit{et al}., ``Stabilized frequency comb with a self-referenced femtosecond Cr:forsterite laser,'' Opt. Lett., \textbf{30}, 932 (2005). [Preview Abstract] |
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