Comparison of two multiplexed portable cold-atom vacuum standards

TL;DR

This study compares two portable cold-atom vacuum standards based on ultracold lithium atoms, demonstrating their agreement and identifying sources of outgassing to improve future measurements.

Contribution

It introduces a method for comparing quantum-based portable vacuum standards and assesses their accuracy and operational challenges.

Findings

The two pCAVS detected a leak of about 10^{-6} Pa L/s.

They measured a vacuum pressure of approximately 40 nPa with 2.6% uncertainty.

Operation causes additional outgassing that can be mitigated with better thermal management.

Abstract

We compare the vacuum measured by two portable cold-atom vacuum standards (pCAVS) based on ultracold $^7$Li atoms. The pCAVS 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 pCAVS together detected a leak with a rate on the order of $10^{-6}$ Pa L/s. After fixing the leak, the pCAVS measured a pressure of about 40 nPa with 2.6 % uncertainty. The two pCAVS 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.