Comparison of two multiplexed portable cold-atom vacuum standards

Abstract

We compare the vacuum measured by two portable cold-atom vacuum standards (pCAVSs) based on ultracold 7Li atoms. pCAVSs are quantum-based standards that use a priori scattering calculations to convert a measured loss rate of cold atoms from a conservative trap into a background gas pressure. Our pCAVS devices share the same laser system and measure the vacuum concurrently. The two pCAVSs together detected a leak with a rate on the order of 10−6 Pa l/s. After fixing the leak, the pCAVS measured pressure of about 40 nPa with 2.6% uncertainty. The two pCAVSs agree within their uncertainties, even when swapping some of their component parts. Operation of the pCAVS was found to cause some additional outgassing, on the order of 10−8 Pa l/s, which can be mitigated in the future by better thermal management.