Fig. 2: Spectroscopic beam cell characterization.
a Source cavity absorption (gray) and drift cavity fluorescence at z = 1 mm (red) and z = 11 mm (blue) measures the Rb number density, flux, and the velocity distribution normal to the device surface at 363 K. b Fluorescence at z = 11 mm includes narrow peaks from the atomic beam signal as well as a broad signal corresponding to background Rb vapor (light blue curve). Passive and differential pumping generates a large (≈6500×) Rb partial pressure differential between the source and drift cavities. c The measured atomic beam flux Fmeas and spectral FWHM are plotted versus distance from the capillary array at 363 K. Flux prediction based on nRb,1 (black dashed lines) and the geometrical FWHM limit set by the fluorescence imaging (red dotted line) are shown. Inset shows the estimated total capillary flux Ftot versus device temperature and comparison to the total expected capillary array flux \({F}_{n}\) (dashed line). Error bars represent 68% confidence intervals.
