Publications

F -state quenching with CH ₄ for buffer-gas cooled ¹⁷¹ Y b ⁺ frequency standard [Methane (CH4) for quenching the F-state in trapped Yb+ ions]

Jau, Yuan-Yu J.; Hunker, Jeffrey D.; Schwindt, Peter S.

We report that methane, CH₄, 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) × 10⁶ s^-1 Torr^-1. For applications that use microwave hyperfine transitions of the ground-state ¹⁷¹Y b ions, the CH4 induced frequency shift coefficient and the decoherence rate coefficient are measured as δν/ν = (-3.6 ± 0.1) × 10^-6 Torr^-1 and 1/T2 = (1.5 ± 0.2) × 10⁵ s^-1 Torr^-1. In our buffer-gas cooled 171Y b+ microwave clock system, we find that only ≤10^-8 Torr of CH₄ 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.