Clean, robust alkali sources by intercalation within highly oriented pyrolytic graphite

Abstract

We report the fabrication, characterization, and use of rubidium vapor dispensers based on highly-oriented pyrolytic graphite (HOPG) intercalated with metallic rubidium. Compared to commercial chromate salt dispensers, these intercalated HOPG (IHOPG) dispensers hold an order of magnitude more rubidium in a similar volume, require less than one-fourth the heating power, and emit less than one-half as many impurities. Appropriate processing permits exposure of the IHOPG to atmosphere for over ninety minutes without any adverse effects. Intercalation of cesium and potassium into HOPG have also been demonstrated in the literature, which suggests that IHOPG dispensers may also be be made for those metals.

A passively pumped vacuum package sustaining cold atoms for more than 200 days

“…When the dispenser is turned back on, there is a spike in background pressure: this effect has been noted by others, and is likely due to a release of gas from both the chamber walls and the dispenser material as the dispenser temperature increases. [24] After some time, the pressures return to their values prior to the cycling experiment.…”

“…The dispenser requires 2.15 A current to maintain optimal conditions, or 2.22 W of power. Continued investigation is required to develop techniques to achieve substantially reduced power consumption while maintaining the appropriate alkali [24,25] and background pressures.…”

Stand-alone vacuum cell for compact ultracold quantum technologies

“…The vacuum cell's 25 × 4.0 × 3.2 cm 3 volume could be substantially reduced if the redundant ion pump (the only magnetic component) is removed. This vacuum cell with no active pumping, ≈ 10 −6 mbar pressures and projected helium-limited lifetime of several years will be enhanced in future via a new generation of 'cleaner' atomic reservoirs [34][35][36] .…”

“…A different rubidium source would ameliorate the situation, e.g. lower temperature methods include capturing Rb in graphite, for either thermal 34 or electronic release 35 . Microfabrication-based beam options are also now available 36 .…”

Light-shift mitigation in a microcell-based atomic clock with Symmetric Auto-Balanced Ramsey spectroscopy

“…To date, the clock stability limitation at 1 day on this setup is suspected to come from a possible unstable cell inner atmosphere. This could be related to Ne buffer gas permeation through the glass windows 36 , materials degassing, or dispenser pollution 37 .…”