Progress towards a primary, ultracold-atom-based pressure standard in the XHV regime

Preparation and evaluation of ultra-high-vacuum (UHV) and extreme-high-vacuum (XHV) environments is critical for high-quality semiconductor fabrication and emerging quantum technologies. Vacuum sensors for these pressure ranges, such as ion-gauges, are not primary (i.e., they require calibration themselves) and have large, poorly-understood uncertainties. We present our progress towards a primary standard for vacuum measurement in the XHV using a gas of ultra-cold atoms confined in a magnetic trap. Our apparatus will allow high-accuracy measurements of atom-molecule collision cross-sections that are necessary to extract the vacuum pressure from the observed background-gas-limited lifetime of the trapped atoms. We are also developing a chip-scale atom trap that integrates all the optics and electromagnets required to create magnetically-trapped, ultra-cold gases. This nano-fabricated atom-trapping chip will form the basis for a deployable, primary vacuum sensor with embedded traceability that can replace an ion gauge.