We have determined the absolute populations of argon metastable states in the plasma of a high-frequency discharge in a pure argon atmosphere and in a mixture of argon and silane.
Non-local density functional theory, as implemented in the code DMol, has been used to calculate the electron affinity of a set of 44 small atoms and molecules. A judicious choice of basis sets ...produces a root mean square deviation from recommended values of 0.1 eV and 0.3 eV for atoms and small molecules (with positive electron affinities) respectively. Applying DMol to calculations of temporary anion states or resonances of linear alkanes to n = 36 (where n is the number of carbon atoms) a gradual increase in electron affinity is predicted which appears to have converged by n = 36 to -0.75 eV (in agreement with experimental data for C
36
and polyethylene).
The initial stage of the positive column formation in an argon glow discharge is investigated both experimentally and theoretically. A decrease in the plasma radiation intensity (the so-called 'dark ...phase') was observed experimentally over a time period of about 1 ms. A similar dip was also observed in the time dependence of the electric field strength. The time evolution of the population of the lowest metastable state of Ar was measured. A relevant theoretical model has been developed and used to perform calculations for the actual experimental conditions. A comparison between the numerical and experimental results shows that the model adequately describes the processes that occur during the formation of the positive column in an argon glow discharge. Experimental and theoretical study shows that the dark-phase effect is related to an excessive amount of metastable Ar atoms at the beginning of a discharge and, consequently, to high rates of stepwise ionization and chemionization.
A thermal atomic beam of dysprosium atoms is cooled using the 4f{sup 10}6s{sup 2}(J=8){yields}4f{sup 10}6s6p(J=9) transition at 421 nm. The cooling is done via a standing light wave orthogonal to the ...atomic beam. Efficient transverse cooling to the Doppler limit is demonstrated for all observable isotopes of dysprosium. Branching ratios to metastable states are demonstrated to be <5x10{sup -4}. A scheme for enhancement of the nonzero-nuclear-spin-isotope cooling and a method for direct identification of possible trap states are proposed.
We investigate the relaxation of a superconducting qubit for the case when its detector, the Josephson bifurcation amplifier, remains latched in one of its two (meta)stable states of forced ...vibrations. The qubit relaxation rates are different in different states. They can display strong dependence on the qubit frequency and resonant enhancement, which is due to quasienergy resonances. Coupling to the driven oscillator changes the effective temperature of the qubit.
We present a scheme to realize the basic two-qubit logic gates such as the quantum phase gate and the controlled-NOT gate using a detuned optical cavity interacting with a three-level Raman system. ...We discuss the role of Stark shifts, which are as important as the terms leading to the two-photon transition. The operation of the proposed logic gates involves metastable states of the atom and hence is not affected by spontaneous emission. These ideas can be extended to produce multiparticle entanglement.
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