Person: Doyle, John
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Doyle
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Doyle, John
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Publication Methods, analysis, and the treatment of systematic errors for the electron electric dipole moment search in thorium monoxide(IOP Publishing, 2017-07-25) Baron, Jacob; Campbell, W C; DeMille, D; Doyle, John; Gabrielse, Gerald; Gurevich, Y V; Hess, P W; Hutzler, Nicholas; Kirilov, E; Kozyryev, I; O’Leary, B R; Panda, C D; Parsons, M F; Spaun, B; Vutha, A C; West, A D; West, E PWe recently set a new limit on the electric dipole moment of the electron (eEDM) (J Baron et al and ACME collaboration 2014 Science 343 269–272), which represented an order-of-magnitude improvement on the previous limit and placed more stringent constraints on many charge-parity violating extensions to the standard model. In this paper we discuss the measurement in detail. The experimental method and associated apparatus are described, together with the techniques used to isolate the eEDM signal. In particular, we detail the way experimental switches were used to suppress effects that can mimic the signal of interest. The methods used to search for systematic errors, and models explaining observed systematic errors, are also described. We briefly discuss possible improvements to the experiment.Publication Stimulated Raman Adiabatic Passage Preparation of a Coherent Superposition of ThO H3Δ1 States for an Improved Electron Electric-Dipole-Moment Measurement(American Physical Society (APS), 2016) Panda, Cristian; O, B. R.; West, A. D.; Baron, J.; Hess, P; Hoffman, C.; Kirilov, E; Overstreet, C. B.; West, Elizabeth Petrik; DeMille, D.; Doyle, John; Gabrielse, GeraldExperimental searches for the electron electric-dipole moment (EDM) probe new physics beyond the standard model. The current best EDM limit was set by the ACME Collaboration [Science 343, 269 (2014), 10.1126/science.1248213], constraining time-reversal symmetry (T ) violating physics at the TeV energy scale. ACME used optical pumping to prepare a coherent superposition of ThO H3Δ1 states that have aligned electron spins. Spin precession due to the molecule's internal electric field was measured to extract the EDM. We report here on an improved method for preparing this spin-aligned state of the electron by using stimulated Raman adiabatic passage (STIRAP). We demonstrate a transfer efficiency of 75 %±5 % , representing a significant gain in signal for a next-generation EDM experiment. We discuss the particularities of implementing STIRAP in systems such as ours, where molecular ensembles with large phase-space distributions are transferred via weak molecular transitions with limited laser power and limited optical access.Publication Spin-Orbit Suppression of Cold Inelastic Collisions of Aluminum and Helium(American Physical Society (APS), 2013) Connolly, Colin; Au, Yat Shan; Chae, Eunmi; Tscherbul, Timur V.; Buchachenko, Alexei A.; Lu, Hsin-I; Ketterle, Wolfgang; Doyle, JohnWe present a quantitative study of suppression of cold inelastic collisions by the spin-orbit interaction. We prepare cold ensembles of \(>10^{11} Al(^2P_{1/2})\) atoms via cryogenic buffer-gas cooling and use a single-beam optical pumping method to measure their magnetic (mJ-changing) and fine-structure (J-changing) collisions with \(^3He\) atoms at millikelvin temperatures over a range of magnetic fields from 0.5 to 6 T. The experimentally determined rates are in good agreement with the functional form predicted by quantum scattering calculations using ab initio potentials. This comparison provides direct experimental evidence for a proposed model of suppressed inelasticity in collisions of atoms in \(^2P_{1/2}\) states [T. V. Tscherbul et al., Phys. Rev. A 80, 040701(R) (2009)], which may allow for sympathetic cooling of other \(^2P_{1/2}\) atoms (e.g., In, Tl and metastable halogens).Publication Formation and dynamics of van der Waals molecules in buffer-gas traps(Royal Society of Chemistry (RSC), 2011) Brahms, Nathan; Tscherbul, Timur V.; Zhang, Peng; Kłos, Jacek; Forrey, Robert C.; Au, Yat Shan; Sadeghpour, H. R.; Dalgarno, Alexander; Doyle, John; Walker, Thad G.We show that weakly bound He-containing van der Waals molecules can be produced and magnetically trapped in buffer-gas cooling experiments, and provide a general model for the formation and dynamics of these molecules. Our analysis shows that, at typical experimental parameters, thermodynamics favors the formation of van der Waals complexes composed of a helium atom bound to most open-shell atoms and molecules, and that complex formation occurs quickly enough to ensure chemical equilibrium. For molecular pairs composed of a He atom and an S-state atom, the molecular spin is stable during formation, dissociation, and collisions, and thus these molecules can be magnetically trapped. Collisional spin relaxation is too slow to affect trap lifetimes. However, 3He-containing complexes can change spin due to adiabatic crossings between trapped and untrapped Zeeman states, mediated by the anisotropic hyperfine interaction, causing trap loss. We provide a detailed model for Ag3He molecules, using ab initio calculation of Ag–He interaction potentials and spin interactions, quantum scattering theory, and direct Monte Carlo simulations to describe formation and spin relaxation in this system. The calculated rate of spin-change agrees quantitatively with experimental observations, providing indirect evidence for molecular formation in buffer-gas-cooled magnetic traps. Finally, we discuss the possibilities for spectroscopic detection of these complexes, including a calculation of expected spectra for Ag3He, and report on our spectroscopic search for Ag3He, which produced a null result.Publication Rotational State Microwave Mixing for Laser Cooling of Complex Diatomic Molecules(American Physical Society (APS), 2015) Yeo, Mark; Hummon, Matthew T.; Collopy, Alejandra L.; Yan, Bo; Hemmerling, Boerge; Chae, Eunmi; Doyle, John; Ye, JunWe demonstrate the mixing of rotational states in the ground electronic state using microwave radiation to enhance optical cycling in the molecule yttrium (II) monoxide (YO). This mixing technique is used in conjunction with a frequency modulated and chirped continuous wave laser to slow longitudinally a cryogenic buffer-gas beam of YO. We generate a flux of YO belowPublication Buffer-gas cooling of atomic and molecular beams(American Physical Society (APS), 2002) Egorov, Dima; Lahaye, Thierry; Schöllkopf, Wieland; Friedrich, Bretislav; Doyle, JohnWe demonstrate direct loading and cooling of a thermal beam into a cryogenic helium buffer gas. Our test species is rubidium; we observe a thermal beam with 3x10^13 s^-1 flux entering a cryocell and thermalizing with a 4.2-K buffer gas. There is no evidence of clustering or other spurious loss mechanisms. The cooling technique should be applicable to a wide variety of species, including radicals.Publication Evaporative cooling of atomic chromium(American Physical Society (APS), 2002) Weinstein, Jonathan D.; deCarvalho, Robert; Hancox, Cindy; Doyle, JohnWe report the magnetic trapping and evaporative cooling of bosonic and fermionic isotopes of atomic chromium. Using a cryogenic helium buffer gas, 10^12 chromium atoms are trapped at an initial temperature of ~1 K. The chromium atoms are then cooled adiabatically and evaporatively to temperatures as low as ~10 mK. Elastic and inelastic ^52Cr collisional cross sections are measured over this temperature range. Prospects for simultaneously creating a ^52Cr Bose-Einstein condensate and ^53Cr Fermi degenerate gas will be discussed.Publication Zeeman spectroscopy of CaH molecules in a magnetic trap(AIP Publishing, 1999) Friedrich, Bretislav; Weinstein, Jonathan D.; deCarvalho, Robert; Doyle, JohnIn a recent experiment [Weinstein et al., Nature 395, 148 (1998)] we magnetically trapped 108108ground-statecalcium monohydride molecules, CaH(X2Σ,v″=0,J″=0).CaH(X 2Σ,v″=0, J″=0). The molecules were prepared by laser ablation of a solid sample of CaH2CaH2 and loaded via thermalization with a cold (<1(<1 K) 3He3He buffer gas. The magnetic trap was formed by superconducting coils arranged in the anti-Helmholtz configuration. The detection was done by laser fluorescence spectroscopy excited at 635635 nm (in the B2Σ,v′=0−X2Σ,v″=0B 2Σ,v′=0−X 2Σ,v″=0 band) and detected at 692692 nm (within the B,v′=0−X,v″=1B,v′=0−X,v″=1 band). Both a photomultiplier tube and a CCD camera were used. Due to the thermalization of molecular rotation, only a transition from the lowest rotational state could be detected at zero field, N′=1,J′=3/2←N″=0,J″=1/2.N′=1, J′=3/2←N″=0, J″=1/2. In the magnetic field this rotational transition splits into two features, one shifted towards lower and one towards higher frequencies. The measured shifts are linear in field strength and indicate a small difference (0.02 μB)μB) in the magnetic moments between the ground and excited states. Here we present a theoretical analysis of the observed magnetic shifts. These are identified as arising from a rotational perturbation of the B2Σ,v′=0B 2Σ,v′=0 state by a close-lying A2Π,v′=1A 2Π,v′=1 state that lends the B state some of its A character. We find that the Hamiltonian can be well approximated by a 3×33×3 matrix built out of elements that connect states from within the Σ-doublet and the 2Π3/22Π3/2 manifolds. The interaction parameter describing the Σ−Π coupling in the Zeeman Hamiltonian is determined from the observed shifts and the field-free molecular parameters of CaH given by Berg and Klyning [Phys. Scr. 10, 331 (1974)] and by Martin [J. Mol. Spectrosc 108, 66 (1984)].Publication Advanced cold molecule electron EDM(EDP Sciences, 2013) Campbell, Wesley; Chan, Cheong; DeMille, David; Doyle, John; Gabrielse, Gerald; Gurevich, Yulia; Hess, Paul; Hutzler, Nicholas; Kirilov, Emil; O'Leary, Brendon; West, Elizabeth Petrik; Spaun, Ben; Vutha, AmarMeasurement of a non-zero electric dipole moment (EDM) of the electron within a few orders of magnitude of the current best limit of |de| < 1.05×10−27 e · cm would be an indication of physics beyond the Standard Model. The ACME Collaboration is searching for an electron EDM by performing a precision measurement of electron spin precession in the metastable H 3Delta_1 state of thorium monoxide (ThO) using a slow, cryogenic beam. We discuss the current status of the experiment. Based on a data set acquired from 14 hours of running time over a period of 2 days, we have achieved a 1-sigma statistical uncertainty of d(de) = 1×10^−28 e · cm/√T ,where T is the running time in days.Publication Spin-Exchange Collisions of Submerged Shell Atoms Below 1 Kelvin(American Physical Society (APS), 2007) Harris, J. G. E.; Nguyen, S. V.; Doret, S. C.; Ketterle, W.; Doyle, JohnAngular momentum changing collisions can be suppressed in atoms whose valence electrons are submerged beneath filled shells of higher principle quantum number. To determine whether spin-exchange collisions are suppressed in these ‘‘submerged shell’’ atoms, we measured collisional rates for six hyperfine states of Mn at T < 1 K. Although the 3d valence electrons in Mn are submerged beneath a filled 4s orbital, we find spin-exchange rate coefficients similar to Na and H (both nonsubmerged shell atoms).