Bulletin of the American Physical Society
2013 Joint Meeting of the APS Division of Atomic, Molecular & Optical Physics and the CAP Division of Atomic, Molecular & Optical Physics, Canada
Volume 58, Number 6
Monday–Friday, June 3–7, 2013; Quebec City, Canada
Session C2: Focus Session: Searches for Permanent Electric Dipole Moments |
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Chair: Larry Hunter, Amherst College Room: 200B |
Tuesday, June 4, 2013 2:00PM - 2:30PM |
C2.00001: The YbF electron EDM search Invited Speaker: B.E. Sauer The standard model of particle physics predicts that, due to time reversal symmetry, the permanent electric dipole moment (EDM) of the electron is very nearly zero. Many extensions to the standard model predict an electron EDM or other T-violating effects just below current experimental limits, thus there is great interest in new experiments and in improving current experimental precision. I will discuss our recent measurement of the electron EDM using YbF molecules. YbF is particularly sensitive to the electron EDM. This experiment uses a form of laser-radiofrequency double resonance spectroscopy to search for very small energy differences between hyperfine levels in a strong electric field. In addition to describing the experimental and analysis techniques, I will give an overview of the techniques we use to check for systematic errors. I will also describe improvements to the experiment now under way which promise several orders of magnitude improvement in sensitivity. [Preview Abstract] |
Tuesday, June 4, 2013 2:30PM - 3:00PM |
C2.00002: The ACME electron electric dipole moment search Invited Speaker: David DeMille Observation of a non-zero electric dipole moment (EDM) of the electron, $d_e$, within a few orders of magnitude of the current limit $|d_e| < 1.05 \times 10^{-27}~e\cdot$cm would be an indication of CP violation in physics beyond the Standard Model. Numerous extensions to the Standard Model predict a value of $d_e$ in this range. The ACME Collaboration is searching for an electron EDM, by performing a precision measurement of spin precession signals from electrons in thorium monoxide (ThO) molecules. In this molecule, the EDM experiences a large electric field ($\sim\! 100$ GV/cm) that amplifies the spin precession. In addition, several properties of the molecular state make it possible to suppress many anticipated sources of systematic error. Our experiment uses a slow and bright cryogenic molecular beam to achieve unprecedented statistical accuracy. We now routinely take data with a 1$\sigma$ statistical uncertainty of $\delta d_e \approx 1.0-1.5 \times 10^{-28}/\sqrt{T}~e\cdot$cm, where $T$ is the running time in days. We will present the current status of the experiment. [Preview Abstract] |
Tuesday, June 4, 2013 3:00PM - 3:12PM |
C2.00003: Final results from the PbO electron electric dipole moment search Stephen Eckel, Paul Hamilton, Emil Kirilov, Hunter Smith, David DeMille We present the final results of an experiment to search for the electron EDM, using the polar molecule PbO. PbO offers several advantages compared to atoms, including a much larger effective internal electric field ($>10$~GV/cm) and parity doubling. The latter can be used to reverse the effective internal electric field without reversing the laboratory electric field, which allows for significant rejection of systematic errors. Our experiment uses a high-temperature vapor cell to obtain significant density of PbO. The problems inherent to working in this environment--such as large leakage currents and electric field imperfections due to uncontrolled electron emission--provide one of the most rigorous tests of the power of this systematic error rejection method. Despite these problems, we obtain a limit on the EDM of $d_e<2\times10^{-26}~e\cdot$cm, only a factor of 20 from the current experimental limit. The use of parity-doublet states for systematic rejection is a common feature of molecules with similar energy structure, and our methods should be applicable to other experiments that use species such as ThO, WC, and HfF$^+$. [Preview Abstract] |
Tuesday, June 4, 2013 3:12PM - 3:24PM |
C2.00004: State-sensitive detection of HfF+ for eEDM search Kang-Kuen Ni, Huanqian Loh, Matt Grau, Kevin Cossel, Daniel Gresh, Jun Ye, Eric Cornell HfF+ can be a sensitive probe for measurement of the electron electric dipole moment due to the large effective internal electric field. However, efficient detection of the state of molecules has been one bottleneck. We have now developed a new detection scheme based on efficient ion counting. The state information of the HfF+ is read out via a two-photon dissociation pulse. The first photon drives a state-sensitive transition and the second photon dissociates the molecule into Hf+ and F. Through mass-resolved time-of-flight ion detection, we count Hf+ ions produced from HfF+ in the specified detected state. The efficiency is 100-fold increased compared to our previous readout method, laser-induced fluorescence. [Preview Abstract] |
Tuesday, June 4, 2013 3:24PM - 3:36PM |
C2.00005: Towards an electron electric dipole moment search with trapped HfF+ molecular ions Huanqian Loh, Kevin Cossel, Kang-Kuen Ni, Matt Grau, Daniel Gresh, Jun Ye, Eric Cornell The search for an electron electric dipole moment (eEDM) serves as a sensitive probe for physics beyond the Standard Model. The $^3\Delta_1$ metastable state of the HfF$^+$ molecular ion is a suitable candidate for the eEDM search because of its high effective electric field and potentially long spin coherence times. By performing STIRAP in the presence of a rotating electric field and a magnetic field, we have prepared HfF$^+$ ions in the desired $^3\Delta_1$ states belonging to an eEDM sensitive transition and mapped out relevant spectroscopic parameters. We report our results on the coherent state transfer and spectroscopy of trapped molecular ions in a rotating field. [Preview Abstract] |
Tuesday, June 4, 2013 3:36PM - 3:48PM |
C2.00006: Measurement of small vector light shifts for an eEDM search Neal Solmeyer, Kunyan Zhu, Cheng Tang, David S. Weiss Optical lattices are an important tool for precision measurements, but the associated vector light shifts can compromise those measurements. As part of an electron electric dipole moment (eEDM) search, we have measured the vector light shift due to a cavity built-up optical lattice using a variation of the Hanle effect on trapped spin-polarized Cs atoms. The measurement is linearly sensitive to the electric field of the non-linearly polarized light, which allows unprecedentedly accurate measurements of the absolute linear polarization quality, to the level of 10$^{-9}$ in fractional intensity. This has in turn allowed us to demonstrably linearly polarize the optical lattice beams to within 2 x 10$^{-8}$. A 50 $\mu $K deep 1.064 $\mu $m optical lattice with this polarization gives a 6 Hz vector light shift in Cs. Our approach to improving linear polarization may also find applications in optical lattice clocks, magnetometery and quantum computing. [Preview Abstract] |
Tuesday, June 4, 2013 3:48PM - 4:00PM |
C2.00007: Magnetometry in the Munich Neutron Electric Dipole Moment (nEDM) Experiment Skyler Degenkolb Neutron EDM measurements rely on sensitive magnetometry to decouple signal from systematic errors. State-of-the-art co-magnetometers use hyperpolarized diamagnetic atoms, chosen for small spin-flip cross-sections and long coherence times. In particular, the 254nm $^{199}$Hg line is used to polarize and detect via Hg lamps or lasers. We present a comprehensive scheme of Hg co-magnetometers, external magnetometers and gradiometers inside passive and active shields. Hg gas is pumped and probed by a diode laser with two doubling stages whose UV output is locked to the 254nm line at the point of vanishing light shift; adjacent cells containing Hg and/or other species are used to extract systematics correlated with material properties of Hg (e.g., center-of-mass displacements or georotational shifts). Vapor cell magnetometers of Hg or Cs are used for comparison, and to guide apparatus installation. The vibration-isolated experiment takes place within passive mu-metal and aluminum shields, inside a non-magnetic experimental hall. A magnetically shielded room, monitored by 180 fluxgate magnetometers which generate error signals for 24 independent external compensation coils, contains the passive shield. Design and performance of the composite system will be discussed. [Preview Abstract] |
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