NASA's Cold Atom Lab (CAL): system development and ground test status

We report the status of the Cold Atom Lab (CAL) instrument to be operated aboard the International Space Station (ISS). Utilizing a compact atom chip-based system to create ultracold mixtures and degenerate samples of ⁸⁷Rb, ³⁹K, and ⁴¹K, CAL is a multi-user facility developed by NASA's Jet Propulsion Laboratory to provide the first persistent quantum gas platform in the microgravity conditions of space. Within this unique environment, atom traps can be decompressed to arbitrarily weak confining potentials, producing a new regime of picokelvin temperatures and ultra-low densities. Further, the complete removal of these confining potential allows the free fall evolution of ultracold clouds to be observed on unprecedented timescales compared to earthbound instruments. This unique facility will enable novel ultracold atom research to be remotely performed by an international group of principle investigators with broad applications in fundamental physics and inertial sensing. Here, we describe the development and validation of critical CAL technologies, including demonstration of the first on-chip Bose-Einstein condensation (BEC) of ⁸⁷Rb with microwave-based evaporation and the generation of ultracold dual-species quantum gas mixtures of ³⁹K/⁸⁷Rb and ⁴¹K/⁸⁷Rb in an atom chip trap via sympathetic cooling.