F-state quenching with CH{sub 4} for buffer-gas cooled {sup 171}Y b{sup +} frequency standard

• Published in: AIP advances Vol. 5; no. 11
• Main Authors: Jau, Y.-Y., Hunker, J. D., Schwindt, P. D. D.
• Format: Journal Article
• Language: English
• Published: United States 15.11.2015
• Subjects: ATOMIC AND MOLECULAR PHYSICS; BORON IONS; BUFFERS; F STATES; GROUND STATES; HYPERFINE STRUCTURE; METHANE; MICROWAVE RADIATION; QUENCHING; TRAPPING; YTTERBIUM 171; YTTERBIUM IONS
• ISSN: 2158-3226; 2158-3226

We report that methane, CH{sub 4}, can be used as an efficient F-state quenching gas for trapped ytterbium ions. The quenching rate coefficient is measured to be (2.8 ± 0.3) × 10{sup 6} s{sup −1} Torr{sup −1}. For applications that use microwave hyperfine transitions of the ground-state {sup 171}Y b ions, the CH{sub 4} induced frequency shift coefficient and the decoherence rate coefficient are measured as δν/ν = (−3.6 ± 0.1) × 10{sup −6} Torr{sup −1} and 1/T{sub 2} = (1.5 ± 0.2) × 10{sup 5} s{sup −1} Torr{sup −1}. In our buffer-gas cooled {sup 171}Y b{sup +} microwave clock system, we find that only ≤10{sup −8} Torr of CH{sub 4} is required under normal operating conditions to efficiently clear the F-state and maintain ≥85% of trapped ions in the ground state with insignificant pressure shift and collisional decoherence of the clock resonance.