This letter reports on the generation of a tunable buffer gas mixture within microfabricated alkali vapor cells. We show that the combination of low-permeation windows with sequential openings of laser-actuated break-seals enables adjustment of a helium-neon (He-Ne) noble gas mixture, fully compatible with alkali metal dispensers. The gas reservoirs and the main cell cavities are initially sealed at the wafer level under distinct helium and neon atmospheres, respectively. Within each cell, after Cs vapor is released from the dispenser, the break-seals are successively actuated to incrementally increase the helium fraction in the buffer gas mixture. This process shifts the atomic clock frequency turnover temperature toward higher values. As an illustration, one of the fabricated cells was operated at 95
∘C in a coherent population trapping clock, achieving a fractional frequency stability of 9$\times
10^{-11}$ at one-day integration time. These results demonstrate the feasibility of precisely tuning buffer gas compositions in microfabricated vapor cells and support the suitability of He-Ne mixtures for miniature atomic clock applications.
Hybrid spin-exchange optical pumping is widely used in precision measurements and tests of fundamental physics. In these researches and applications, accurate measurement of the spin polarizations of hybrid alkali atoms and noble gas atoms has a significant role. Here we propose a novel method of measuring the spin polarizations of hybrid K-Rb and21Ne atoms simultaneously. We study the mixture of the slowing-down factors of hybrid alkali atoms due to spin-exchange interactions between hybrid alkali atoms, and the resonance-frequency shift of alkali atoms due to spin-exchange interactions with noble-gas atoms. We investigate the relationship between the hybrid resonance frequency and the polarizations. The spin polarizations of alkali atoms and noble-gas atoms have been measured based on this method, which is from 0.082 to 0.756 and from 0.018 to 0.124 with uncertainties smaller than 10.4 % and 12.7 % respectively. This method is promising for the applications requiring simultaneous and real-time measurement of the polarizations of alkali and noble-gas atoms, such as inertial sensors and tests of fundamental physics.
We report the first studies of magnetic decoupling of the spin relaxation of alkali-metal atoms due to binary collisions with buffer gases. When binary collisions are the dominant relaxation mechanism, the relaxation and its magnetic decoupling are well described by the
S-damping rate ${\ensuremath{\Gamma}}_{\mathrm{SD}}$ due to the spin-rotation interaction $\ensuremath{\gamma}\mathbf{N}\ifmmode \dot{}\else \.{}\fi{}\mathbf{S}$, the spin exchange rate ${\ensuremath{\Gamma}}_{\mathrm{EX}}$ for collisions between alkali atoms, and a new ``Carver rate'' ${\ensuremath{\Gamma}}_{\mathrm{C}}$, due to the pressure-shift interaction $\ensuremath{\delta}A\mathbf{I}\ifmmode \dot{}\else \.{}\fi{}\mathbf{S}$, which can substantially broaden the magnetic decoupling curve while having no influence on the zero-field rates.