Edmund R. Meyer

Candidate molecular ions for an electron electric dipole moment experiment

This paper is a theoretical work in support of a newly proposed experiment [R. Stutz and E. Cornell, Bull. Am. Soc. Phys. 89, 76 (2004)] that promises greater sensitivity to measurements of the electrons electric dipole moment (EDM) based on the trapping of molecular ions. Such an experiment requires the choice of a suitable molecule that is both experimentally feasible and possesses an expectation of a reasonable EDM signal. We find that the molecular ions PtH{sup +} and HfH{sup +} are both suitable candidates in their low-lying {sup 3}{delta} states. In particular, we anticipate that the effective electric fields generated inside these molecules are approximately 73 and -17 GV/cm, respectively. As a byproduct of this discussion, we also explain how to make estimates of the size of the effective electric field acting in a molecule, using commercially available nonrelativistic molecular structure software.

Prospects for an electron electric-dipole moment search in metastable ThO and ThF

The observation of an electron electric-dipole moment EEDM would have major ramifications for the standard model of physics. Polar molecules offer a near-ideal laboratory for such searches due to the large effective electric field Feff, on order of tens of GV/cm that can be easily oriented in the laboratory frame. We present an improved method for simply and accurately determining Feff, in a heavy polar molecule, allowing for a quick determination of candidates for an EEDM experiment. We apply this method to ThO and ThF + , both of which possess metastable 3 electronic states. The values of Feff in ThO and ThF + are estimated to be 104 GV/cm and 90 GV/cm, respectively, making them two of the best known candidates for the EEDM search.

Precision Spectroscopy of Polarized Molecules in an Ion Trap

Toward a New Physics The search for physics beyond the Standard Model is carried out at accelerator facilities such as the Large Hadron Collider but also on a smaller scale in atomic and molecular physics experiments. One of the signatures of this “new physics” would be a nonvanishing electric dipole moment of the electron, but experiments designed to look for it need to distinguish between the signal and many potential artifacts. Loh et al. (p. 1220) introduce a method based on the spectroscopy of polarized molecular ions that avoids some of the sources of systematic error. A method to measure the electric dipole moment of the electron is demonstrated by using polarized trapped molecular ions. Polar molecules are desirable systems for quantum simulations and cold chemistry. Molecular ions are easily trapped, but a bias electric field applied to polarize them tends to accelerate them out of the trap. We present a general solution to this issue by rotating the bias field slowly enough for the molecular polarization axis to follow but rapidly enough for the ions to stay trapped. We demonstrate Ramsey spectroscopy between Stark-Zeeman sublevels in 180Hf19F+ with a coherence time of 100 milliseconds. Frequency shifts arising from well-controlled topological (Berry) phases are used to determine magnetic g factors. The rotating-bias-field technique may enable using trapped polar molecules for precision measurement and quantum information science, including the search for an electron electric dipole moment.

OH hyperfine ground state : From precision measurement to molecular qubits

We perform precision microwave spectroscopy--aided by Stark deceleration--to reveal the low-magnetic-field behavior of OH in its {sup 2}{pi}{sub 3/2} rovibronic ground state, identifying two field-insensitive hyperfine transitions suitable as qubits and determining a differential Lande g factor of 1.267(5)x10{sup -3} between opposite-parity components of the {lambda} doublet. The data are successfully modeled with an effective hyperfine Zeeman Hamiltonian, which we use to make a tenfold improvement of the magnetically sensitive, astrophysically important {delta}F={+-}1 satellite-line frequencies, yielding 1 720 529 887(10) Hz and 1 612 230 825(15) Hz.

Broadband velocity modulation spectroscopy of HfF + : towards a measurement of the electron electric dipole moment

Precision spectroscopy of trapped HfF + will be used in a search for the permanent electric dipole moment of the electron (eEDM). While this dipole moment has yet to be observed, various extensions to the standard model of particle physics (such as supersymmetry) predict values that are close to the current limit. We present extensive survey spectroscopy of 19 bands covering nearly 5000 cm −1 using both frequency-comb and single-frequency laser velocity-modulation spectroscopy. We obtain high-precision rovibrational constants for eight electronic states inclu ding those that will be necessary for state preparation and r eadout in an actual eEDM experiment.

An electron electric dipole moment search in the X3 Δ1 ground state of tungsten carbide molecules

We identify the X 3Δ1 electronic ground state of tungsten carbide (WC) as a candidate molecular system in which to search for a permanent electric dipole moment (EDM) of the electron. The valence electrons in tungsten carbide experience an effective electric field of order 54 GV cm−1 when the molecule is placed in a laboratory electric field of just a few mV cm−1. Currently, a continuous tungsten carbide molecular beam is under construction. Tungsten atoms are evaporated from a resistively heated tungsten filament and are entrained in a noble gas jet containing a small fraction of methane. Tungsten carbide molecules are formed through the reaction W + CH4 → WC + 2H2.

Electron EDM searches based on alkali or alkaline earth bearing molecules

We introduce four new molecules - YbRb, YbCs, YbSr{sup +}, and YbBa{sup +} - that may prove fruitful in experimental searches for the electric-dipole moment (EDM) of the electron. These molecules can, in principle, be prepared at extremely low temperatures by photoassociating ultracold atoms and therefore may present an advantage over molecular-beam experiments. Here we discuss properties of these molecules and assess the effective electric fields they contribute to an electron EDM measurement.

Product-state control of bi-alkali-metal chemical reactions

exoergicreactioncanbecompletelyturnedoff.Thispossibility is afforded by the fact that, for alkali dimers, the final states of reaction are not terribly different in energy from the reactants. Specifically,weconsidercollisionsofapairofKRbmolecules, prepared in their vibrational ground state (ν1 = ν2 = 0) and particular rotational states n1 and n2. These molecules are, in general, subject to two kinds of reactions: the formation of trimers via

Influence of a humidor on the aerodynamics of baseballs

We investigate whether storing baseballs in a controlled humidity environment significantly affects their aerodynamic properties. We measure the change in diameter and weight of baseballs as a function of relative humidity in which the balls are stored. The trajectories of pitched and batted baseballs are modeled to assess the difference between those stored at 30% relative humidity versus 50% relative humidity. We find that a drier baseball will curve slightly more than a humidified one for a given pitch velocity and rotation rate. We also find that aerodynamics alone would add 2ft to the distance a wetter baseball ball is hit. This increased distance is compensated by a 6ft reduction in the batted distance due to the change in the coefficient of restitution of the ball. We discuss consequences of these results for baseball played at Coors Field in Denver, where baseballs have been stored in a humidor at 50% relative humidity since 2002.

Alternative first-principles calculation of entropy for liquids

We present an alternative method for interpreting the velocity autocorrelation function (VACF) of a fluid with application to extracting the entropy in a manner similar to the methods developed by Lin et al. [J. Chem. Phys. 119, 11792 (2003)]JCPSA60021-960610.1063/1.1624057 and improved upon by Desjarlais [Phys. Rev. E 88, 062145 (2013)]PLEEE81539-375510.1103/PhysRevE.88.062145. The liquid VACF is decomposed into two components, one gas and one solid, and each contributions entropic portion is calculated. However, we fit both the gas and solid portions of the VACF in the time domain. This approach is applied to a single-component liquid (a two-phase model of liquid Al at the melt line) and two different two-component systems: a superionic-to-superionic (bcc to fcc) phase transition in H_{2}O at high temperatures and pressures and a metastable liquid state of MgO. For all three examples, comparisons to existing results in the literature demonstrate the validity of our alternative.