7 results found
Lim J, Almond J, Trigatzis M, et al., 2018, Laser cooled YbF molecules for measuring the electron's electric dipole moment, Physical Review Letters, Vol: 120, ISSN: 0031-9007
We demonstrate one-dimensional sub-Doppler laser cooling of a beam of YbF molecules to 100 μK. This is a key step towards a measurement of the electron's electric dipole moment using ultracold molecules. We compare the effectiveness of magnetically-assisted and polarization-gradient sub-Doppler cooling mechanisms. We model the experiment and fi nd good agreement with our data.
We present the properties and advantages of a new magneto-optical trap (MOT) where blue- detuned light drives ‘type-II’ transitions that have dark ground states. Using ⁸⁷Rb, we reach a radiation-pressure-limited density exceeding 10¹¹ cm⁻³ and a temperature below 30 μK. The phase-space density is higher than in normal atomic MOTs, and a million times higher than comparable red-detuned type-II MOTs, making the blue-detuned MOT particularly attractive for molecular MOTs which rely on type-II transitions. The loss of atoms from the trap is dominated by ultracold collisions between Rb atoms. For typical trapping conditions, we measure a loss rate of 1.8(4) × 10⁻¹⁰ cm³ s⁻¹.
Sauer BE, Devlin JA, Rabey IM, 2017, A big measurement of a small moment, New Journal of Physics, Vol: 19, ISSN: 1367-2630
A beam of ThO molecules has been used to make the most precise measurement of the electron's electric dipole moment (EDM) to date. In their recent paper, the ACME collaboration set out in detail their experimental and data analysis techniques. In a tour-de-force, they explain the many ways in which their apparatus can produce a signal which mimics the EDM and show how these systematic effects are measured and controlled.
Devlin J, Tarbutt M, 2016, Three-dimensional Doppler, polarization-gradient, and magneto-optical forces for atoms and molecules with dark states, New Journal of Physics, Vol: 18, ISSN: 1367-2630
We theoretically investigate the damping and trapping forces in a three-dimensional magneto-optical trap (MOT), by numerically solving the optical Bloch equations. We focus on the case where there are dark states because the atom is driven on a ”type-II" system where the angular momentum of the excited state, F', is less than or equal to that of the ground state, F. For these systems we find that the force in a three-dimensional light field has very different behaviour to its one-dimensional counterpart. This differs from the more commonly used “type-I" systems (F' = F +1) where the 1D and 3D behaviours are similar. Unlike type-I systems where, for red-detuned light, both Doppler and sub-Doppler forces damp the atomic motion towards zero velocity, in type-II systems in 3D, the Doppler force and polarization gradient force have opposite signs. As a result, the atom is driven towards a non-zero equilibrium velocity, v₀, where the two forces cancel. We find that v₀² scales linearly with the intensity of the light and is fairly insensitive to the detuning from resonance. We also discover a new magneto-optical force that alters the normal MOT force at low magnetic fields and whose influence is greatest in the type-II systems. We discuss the implications of these findings for the laser cooling and magneto-optical trapping of molecules where type-II transitions are unavoidable in realising closed optical cycling transitions.
Rabey IM, Devlin JA, Hinds EA, et al., 2016, Low magnetic Johnson noise electric field plates for precision measurement, Review of Scientific Instruments, Vol: 87, ISSN: 1089-7623
We describe a parallel pair of high voltage electric field plates designed and constructed to minimise magnetic Johnson noise. They are formed by laminating glass substrates with commercially available polyimide (Kapton) tape, covered with a thin gold film. Tested in vacuum, the outgassing rate is less than 5 x 10 exp(-5) mbar.l/s. The plates have been operated at electric fields up to 8.3 kV/cm, when the leakage current is at most a few hundred pA. The design is discussed in the context of a molecular spin precession experiment to measure the permanent electric dipole moment of the electron.
Devlin J, Tarbutt MR, Kokkin DL, et al., 2015, Measurements of the Zeeman effect in the A(2)Pi and B-2 Sigma(+) states of calcium fluoride, Journal of Molecular Spectroscopy, Vol: 317, Pages: 1-9, ISSN: 1096-083X
The magnetic tuning of the low rotational levels in the (v = 0) X2Σ+, (v = 0) A2Π, and (v = 0) B2Σ+ electronic states of calcium monofluoride, CaF, have been experimentally investigated using high resolution optical Zeeman spectroscopy of a cold molecular beam. The observed Zeeman shifts and splittings are successfully modeled using a traditional effective Hamiltonian approach to account for the interaction between the (v = 0) A2Π and (v = 0) B2Σ+ states. The determined magnetic g-factors for the X2Σ+, B2Σ+ and A2Π states are compared to those predicted by perturbation theory.
Sauer BE, Devlin JA, Hudson JJ, et al., 2013, Time reversal symmetry violation in the YbF molecule, HYPERFINE INTERACTIONS, Vol: 214, Pages: 119-126, ISSN: 0304-3843
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