NASA’s Cold Atom Lab (CAL): Quantum Science and Technology Maturation on the International Space Station

Ultracold gases studies in the microgravity environment of space hold great promise for fundamental physics and for developing quantum sensors with novel and unprecedented capabilities. Pursuing space-enabled quantum science and technology maturation, the CAL facility launched to the International Space Station (ISS) in May 2018 and has been operating since that time as the world’s first multi-user facility for the study of ultra-cold quantum gases in space (1). The unique microgravity environment of the ISS is utilized by the diverse teams of the CAL principal investigators to achieve sub-nanokelvin temperature gases, to study and utilize their quantum properties in an environment free from the perturbing force of gravity, and to observe and interact with these gases in the essentially limitless freefall of Earth’s orbit. In addition to the toolbox of capabilities originally built into CAL, an upgrade in 2020 enabled the study of atom interferometry in orbit (2), and a 2021 upgrade and repair facilitated investigations of the interactions between mixtures of ⁸⁷Rb, ³⁹K, and ⁴¹K and dual-species (⁸⁷Rb - ⁴¹K or ⁸⁷Rb - ³⁹K) atom interferometry (3). We will review the up-to-date quantum gas research explored with CAL and the technical accomplishments to operate, maintain, and upgrade CAL during its tenure in the microgravity environment of the ISS. This research has broad applications in fundamental physics and precision sensing to open the door for future quantum-enabled mission opportunities.